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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
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<title>Mu - 071print.mu</title>
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.muRecipe { color: #ff8700; }
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.muScenario { color: #00af00; }
.Comment { color: #9090ff; }
.Constant { color: #00a0a0; }
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<pre id='vimCodeElement'>
<span class="Comment"># Wrappers around print primitives that take a 'screen' object and are thus</span>
<span class="Comment"># easier to test.</span>

container screen [
  num-rows:number
  num-columns:number
  cursor-row:number
  cursor-column:number
  data:address:array:screen-cell
]

container screen-cell [
  contents:character
  color:number
]

<span class="muRecipe">recipe</span> new-fake-screen [
  <span class="Constant">local-scope</span>
  result:address:screen<span class="Special"> &lt;- </span>new screen:type
  width:address:number<span class="Special"> &lt;- </span>get-address *result, num-columns:offset
  *width<span class="Special"> &lt;- </span><span class="Constant">next-ingredient</span>
  height:address:number<span class="Special"> &lt;- </span>get-address *result, num-rows:offset
  *height<span class="Special"> &lt;- </span><span class="Constant">next-ingredient</span>
  row:address:number<span class="Special"> &lt;- </span>get-address *result, cursor-row:offset
  *row<span class="Special"> &lt;- </span>copy <span class="Constant">0</span>
  column:address:number<span class="Special"> &lt;- </span>get-address *result, cursor-column:offset
  *column<span class="Special"> &lt;- </span>copy <span class="Constant">0</span>
  bufsize:number<span class="Special"> &lt;- </span>multiply *width, *height
  buf:address:address:array:screen-cell<span class="Special"> &lt;- </span>get-address *result, data:offset
  *buf<span class="Special"> &lt;- </span>new screen-cell:type, bufsize
  clear-screen result
  <span class="muControl">reply</span> result
]

<span class="muRecipe">recipe</span> clear-screen [
  <span class="Constant">local-scope</span>
  sc:address:screen<span class="Special"> &lt;- </span><span class="Constant">next-ingredient</span>
  <span class="Comment"># if x exists</span>
  <span class="Delimiter">{</span>
    <span class="muControl">break-unless</span> sc
    <span class="Comment"># clear fake screen</span>
    buf:address:array:screen-cell<span class="Special"> &lt;- </span>get *sc, data:offset
    max:number<span class="Special"> &lt;- </span>length *buf
    i:number<span class="Special"> &lt;- </span>copy <span class="Constant">0</span>
    <span class="Delimiter">{</span>
      done?:boolean<span class="Special"> &lt;- </span>greater-or-equal i, max
      <span class="muControl">break-if</span> done?
      curr:address:screen-cell<span class="Special"> &lt;- </span>index-address *buf, i
      curr-content:address:character<span class="Special"> &lt;- </span>get-address *curr, contents:offset
      *curr-content<span class="Special"> &lt;- </span>copy <span class="Constant">[ ]</span>
      curr-color:address:character<span class="Special"> &lt;- </span>get-address *curr, color:offset
      *curr-color<span class="Special"> &lt;- </span>copy <span class="Constant">7/white</span>
      i<span class="Special"> &lt;- </span>add i, <span class="Constant">1</span>
      <span class="muControl">loop</span>
    <span class="Delimiter">}</span>
    <span class="Comment"># reset cursor</span>
    x:address:number<span class="Special"> &lt;- </span>get-address *sc, cursor-row:offset
    *x<span class="Special"> &lt;- </span>copy <span class="Constant">0</span>
    x<span class="Special"> &lt;- </span>get-address *sc, cursor-column:offset
    *x<span class="Special"> &lt;- </span>copy <span class="Constant">0</span>
    <span class="muControl">reply</span> sc/same-as-ingredient:<span class="Constant">0</span>
  <span class="Delimiter">}</span>
  <span class="Comment"># otherwise, real screen</span>
  clear-display
  <span class="muControl">reply</span> sc/same-as-ingredient:<span class="Constant">0</span>
]

<span class="muRecipe">recipe</span> fake-screen-is-empty? [
  <span class="Constant">local-scope</span>
  sc:address:screen<span class="Special"> &lt;- </span><span class="Constant">next-ingredient</span>
  <span class="muControl">reply-unless</span> sc, <span class="Constant">1/true</span>
  buf:address:array:screen-cell<span class="Special"> &lt;- </span>get *sc, data:offset
  i:number<span class="Special"> &lt;- </span>copy <span class="Constant">0</span>
  len:number<span class="Special"> &lt;- </span>length *buf
  <span class="Delimiter">{</span>
    done?:boolean<span class="Special"> &lt;- </span>greater-or-equal i, len
    <span class="muControl">break-if</span> done?
    curr:screen-cell<span class="Special"> &lt;- </span>index *buf, i
    curr-contents:character<span class="Special"> &lt;- </span>get curr, contents:offset
    i<span class="Special"> &lt;- </span>add i, <span class="Constant">1</span>
    <span class="muControl">loop-unless</span> curr-contents
    <span class="Comment"># not 0</span>
    <span class="muControl">reply</span> <span class="Constant">0/false</span>
  <span class="Delimiter">}</span>
  <span class="muControl">reply</span> <span class="Constant">1/true</span>
]

<span class="muRecipe">recipe</span> print-character [
  <span class="Constant">local-scope</span>
  sc:address:screen<span class="Special"> &lt;- </span><span class="Constant">next-ingredient</span>
  c:character<span class="Special"> &lt;- </span><span class="Constant">next-ingredient</span>
  color:number, color-found?:boolean<span class="Special"> &lt;- </span><span class="Constant">next-ingredient</span>
  <span class="Delimiter">{</span>
    <span class="Comment"># default color to white</span>
    <span class="muControl">break-if</span> color-found?
    color<span class="Special"> &lt;- </span>copy <span class="Constant">7/white</span>
  <span class="Delimiter">}</span>
  bg-color:number, bg-color-found?:boolean<span class="Special"> &lt;- </span><span class="Constant">next-ingredient</span>
  <span class="Delimiter">{</span>
    <span class="Comment"># default bg-color to black</span>
    <span class="muControl">break-if</span> bg-color-found?
    bg-color<span class="Special"> &lt;- </span>copy <span class="Constant">0/black</span>
  <span class="Delimiter">}</span>
<span class="CommentedCode">#?   trace [app], [print character] #? 1</span>
  <span class="Delimiter">{</span>
    <span class="Comment"># if x exists</span>
    <span class="Comment"># (handle special cases exactly like in the real screen)</span>
    <span class="muControl">break-unless</span> sc
    width:number<span class="Special"> &lt;- </span>get *sc, num-columns:offset
    height:number<span class="Special"> &lt;- </span>get *sc, num-rows:offset
    <span class="Comment"># if cursor is out of bounds, silently exit</span>
    row:address:number<span class="Special"> &lt;- </span>get-address *sc, cursor-row:offset
    legal?:boolean<span class="Special"> &lt;- </span>greater-or-equal *row, <span class="Constant">0</span>
    <span class="muControl">reply-unless</span> legal?, sc
    legal?<span class="Special"> &lt;- </span>lesser-than *row, height
    <span class="muControl">reply-unless</span> legal?, sc
    column:address:number<span class="Special"> &lt;- </span>get-address *sc, cursor-column:offset
    legal?<span class="Special"> &lt;- </span>greater-or-equal *column, <span class="Constant">0</span>
    <span class="muControl">reply-unless</span> legal?, sc
    legal?<span class="Special"> &lt;- </span>lesser-than *column, width
    <span class="muControl">reply-unless</span> legal?, sc
    <span class="Comment"># special-case: newline</span>
    <span class="Delimiter">{</span>
      newline?:boolean<span class="Special"> &lt;- </span>equal c, <span class="Constant">10/newline</span>
<span class="CommentedCode">#?       $print c, [ ], newline?, 10/newline</span>
      <span class="muControl">break-unless</span> newline?
      <span class="Delimiter">{</span>
        <span class="Comment"># unless cursor is already at bottom</span>
        bottom:number<span class="Special"> &lt;- </span>subtract height, <span class="Constant">1</span>
        at-bottom?:boolean<span class="Special"> &lt;- </span>greater-or-equal *row, bottom
        <span class="muControl">break-if</span> at-bottom?
        <span class="Comment"># move it to the next row</span>
        *column<span class="Special"> &lt;- </span>copy <span class="Constant">0</span>
        *row<span class="Special"> &lt;- </span>add *row, <span class="Constant">1</span>
      <span class="Delimiter">}</span>
      <span class="muControl">reply</span> sc/same-as-ingredient:<span class="Constant">0</span>
    <span class="Delimiter">}</span>
    <span class="Comment"># save character in fake screen</span>
    index:number<span class="Special"> &lt;- </span>multiply *row, width
    index<span class="Special"> &lt;- </span>add index, *column
    buf:address:array:screen-cell<span class="Special"> &lt;- </span>get *sc, data:offset
    len:number<span class="Special"> &lt;- </span>length *buf
    <span class="Comment"># special-case: backspace</span>
    <span class="Delimiter">{</span>
      backspace?:boolean<span class="Special"> &lt;- </span>equal c, <span class="Constant">8</span>
      <span class="muControl">break-unless</span> backspace?
      <span class="Delimiter">{</span>
        <span class="Comment"># unless cursor is already at left margin</span>
        at-left?:boolean<span class="Special"> &lt;- </span>lesser-or-equal *column, <span class="Constant">0</span>
        <span class="muControl">break-if</span> at-left?
        <span class="Comment"># clear previous location</span>
        *column<span class="Special"> &lt;- </span>subtract *column, <span class="Constant">1</span>
        index<span class="Special"> &lt;- </span>subtract index, <span class="Constant">1</span>
        cursor:address:screen-cell<span class="Special"> &lt;- </span>index-address *buf, index
        cursor-contents:address:character<span class="Special"> &lt;- </span>get-address *cursor, contents:offset
        *cursor-contents<span class="Special"> &lt;- </span>copy <span class="Constant">32/space</span>
        cursor-color:address:number<span class="Special"> &lt;- </span>get-address *cursor, color:offset
        *cursor-color<span class="Special"> &lt;- </span>copy <span class="Constant">7/white</span>
      <span class="Delimiter">}</span>
      <span class="muControl">reply</span> sc/same-as-ingredient:<span class="Constant">0</span>
    <span class="Delimiter">}</span>
<span class="CommentedCode">#?     $print [saving character ], c, [ to fake screen ], cursor, 10/newline</span>
    cursor:address:screen-cell<span class="Special"> &lt;- </span>index-address *buf, index
    cursor-contents:address:character<span class="Special"> &lt;- </span>get-address *cursor, contents:offset
    *cursor-contents<span class="Special"> &lt;- </span>copy c
    cursor-color:address:number<span class="Special"> &lt;- </span>get-address *cursor, color:offset
    *cursor-color<span class="Special"> &lt;- </span>copy color
    <span class="Comment"># increment column unless it's already all the way to the right</span>
    <span class="Delimiter">{</span>
      right:number<span class="Special"> &lt;- </span>subtract width, <span class="Constant">1</span>
      at-right?:boolean<span class="Special"> &lt;- </span>greater-or-equal *column, right
      <span class="muControl">break-if</span> at-right?
      *column<span class="Special"> &lt;- </span>add *column, <span class="Constant">1</span>
    <span class="Delimiter">}</span>
    <span class="muControl">reply</span> sc/same-as-ingredient:<span class="Constant">0</span>
  <span class="Delimiter">}</span>
  <span class="Comment"># otherwise, real screen</span>
  print-character-to-display c, color, bg-color
  <span class="muControl">reply</span> sc/same-as-ingredient:<span class="Constant">0</span>
]

<span class="muScenario">scenario</span> print-character-at-top-left [
  run [
<span class="CommentedCode">#?     $start-tracing #? 3</span>
    <span class="Constant">1</span>:address:screen<span class="Special"> &lt;- </span>new-fake-screen <span class="Constant">3/width</span>, <span class="Constant">2/height</span>
    <span class="Constant">1</span>:address:screen<span class="Special"> &lt;- </span>print-character <span class="Constant">1</span>:address:screen, <span class="Constant">97</span>  <span class="Comment"># 'a'</span>
    <span class="Constant">2</span>:address:array:screen-cell<span class="Special"> &lt;- </span>get *<span class="Constant">1</span>:address:screen, data:offset
    <span class="Constant">3</span>:array:screen-cell<span class="Special"> &lt;- </span>copy *<span class="Constant">2</span>:address:array:screen-cell
  ]
  memory-should-contain [
    <span class="Constant">3</span><span class="Special"> &lt;- </span><span class="Constant">6</span>  <span class="Comment"># width*height</span>
    <span class="Constant">4</span><span class="Special"> &lt;- </span><span class="Constant">97</span>  <span class="Comment"># 'a'</span>
    <span class="Constant">5</span><span class="Special"> &lt;- </span><span class="Constant">7</span>  <span class="Comment"># white</span>
    <span class="Constant">6</span><span class="Special"> &lt;- </span><span class="Constant">0</span>
  ]
]

<span class="muScenario">scenario</span> print-character-color [
  run [
    <span class="Constant">1</span>:address:screen<span class="Special"> &lt;- </span>new-fake-screen <span class="Constant">3/width</span>, <span class="Constant">2/height</span>
    <span class="Constant">1</span>:address:screen<span class="Special"> &lt;- </span>print-character <span class="Constant">1</span>:address:screen, <span class="Constant">97/a</span>, <span class="Constant">1/red</span>
    <span class="Constant">2</span>:address:array:screen-cell<span class="Special"> &lt;- </span>get *<span class="Constant">1</span>:address:screen, data:offset
    <span class="Constant">3</span>:array:screen-cell<span class="Special"> &lt;- </span>copy *<span class="Constant">2</span>:address:array:screen-cell
  ]
  memory-should-contain [
    <span class="Constant">3</span><span class="Special"> &lt;- </span><span class="Constant">6</span>  <span class="Comment"># width*height</span>
    <span class="Constant">4</span><span class="Special"> &lt;- </span><span class="Constant">97</span>  <span class="Comment"># 'a'</span>
    <span class="Constant">5</span><span class="Special"> &lt;- </span><span class="Constant">1</span>  <span class="Comment"># red</span>
    <span class="Constant">6</span><span class="Special"> &lt;- </span><span class="Constant">0</span>
  ]
]

<span class="muScenario">scenario</span> print-backspace-character [
  run [
<span class="CommentedCode">#?     $start-tracing #? 3</span>
    <span class="Constant">1</span>:address:screen<span class="Special"> &lt;- </span>new-fake-screen <span class="Constant">3/width</span>, <span class="Constant">2/height</span>
    <span class="Constant">1</span>:address:screen<span class="Special"> &lt;- </span>print-character <span class="Constant">1</span>:address:screen, <span class="Constant">97</span>  <span class="Comment"># 'a'</span>
    <span class="Constant">1</span>:address:screen<span class="Special"> &lt;- </span>print-character <span class="Constant">1</span>:address:screen, <span class="Constant">8</span>  <span class="Comment"># backspace</span>
    <span class="Constant">2</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">1</span>:address:screen, cursor-column:offset
    <span class="Constant">3</span>:address:array:screen-cell<span class="Special"> &lt;- </span>get *<span class="Constant">1</span>:address:screen, data:offset
    <span class="Constant">4</span>:array:screen-cell<span class="Special"> &lt;- </span>copy *<span class="Constant">3</span>:address:array:screen-cell
  ]
  memory-should-contain [
    <span class="Constant">2</span><span class="Special"> &lt;- </span><span class="Constant">0</span>  <span class="Comment"># cursor column</span>
    <span class="Constant">4</span><span class="Special"> &lt;- </span><span class="Constant">6</span>  <span class="Comment"># width*height</span>
    <span class="Constant">5</span><span class="Special"> &lt;- </span><span class="Constant">32</span>  <span class="Comment"># space, not 'a'</span>
    <span class="Constant">6</span><span class="Special"> &lt;- </span><span class="Constant">7</span>  <span class="Comment"># white</span>
    <span class="Constant">7</span><span class="Special"> &lt;- </span><span class="Constant">0</span>
  ]
]

<span class="muScenario">scenario</span> print-extra-backspace-character [
  run [
    <span class="Constant">1</span>:address:screen<span class="Special"> &lt;- </span>new-fake-screen <span class="Constant">3/width</span>, <span class="Constant">2/height</span>
    <span class="Constant">1</span>:address:screen<span class="Special"> &lt;- </span>print-character <span class="Constant">1</span>:address:screen, <span class="Constant">97</span>  <span class="Comment"># 'a'</span>
    <span class="Constant">1</span>:address:screen<span class="Special"> &lt;- </span>print-character <span class="Constant">1</span>:address:screen, <span class="Constant">8</span>  <span class="Comment"># backspace</span>
    <span class="Constant">1</span>:address:screen<span class="Special"> &lt;- </span>print-character <span class="Constant">1</span>:address:screen, <span class="Constant">8</span>  <span class="Comment"># backspace</span>
    <span class="Constant">2</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">1</span>:address:screen, cursor-column:offset
    <span class="Constant">3</span>:address:array:screen-cell<span class="Special"> &lt;- </span>get *<span class="Constant">1</span>:address:screen, data:offset
    <span class="Constant">4</span>:array:screen-cell<span class="Special"> &lt;- </span>copy *<span class="Constant">3</span>:address:array:screen-cell
  ]
  memory-should-contain [
    <span class="Constant">2</span><span class="Special"> &lt;- </span><span class="Constant">0</span>  <span class="Comment"># cursor column</span>
    <span class="Constant">4</span><span class="Special"> &lt;- </span><span class="Constant">6</span>  <span class="Comment"># width*height</span>
    <span class="Constant">5</span><span class="Special"> &lt;- </span><span class="Constant">32</span>  <span class="Comment"># space, not 'a'</span>
    <span class="Constant">6</span><span class="Special"> &lt;- </span><span class="Constant">7</span>  <span class="Comment"># white</span>
    <span class="Constant">7</span><span class="Special"> &lt;- </span><span class="Constant">0</span>
  ]
]

<span class="muScenario">scenario</span> print-at-right-margin [
  run [
    <span class="Constant">1</span>:address:screen<span class="Special"> &lt;- </span>new-fake-screen <span class="Constant">2/width</span>, <span class="Constant">2/height</span>
    <span class="Constant">1</span>:address:screen<span class="Special"> &lt;- </span>print-character <span class="Constant">1</span>:address:screen, <span class="Constant">97</span>  <span class="Comment"># 'a'</span>
    <span class="Constant">1</span>:address:screen<span class="Special"> &lt;- </span>print-character <span class="Constant">1</span>:address:screen, <span class="Constant">98</span>  <span class="Comment"># 'b'</span>
    <span class="Constant">1</span>:address:screen<span class="Special"> &lt;- </span>print-character <span class="Constant">1</span>:address:screen, <span class="Constant">99</span>  <span class="Comment"># 'c'</span>
    <span class="Constant">2</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">1</span>:address:screen, cursor-column:offset
    <span class="Constant">3</span>:address:array:screen-cell<span class="Special"> &lt;- </span>get *<span class="Constant">1</span>:address:screen, data:offset
    <span class="Constant">4</span>:array:screen-cell<span class="Special"> &lt;- </span>copy *<span class="Constant">3</span>:address:array:screen-cell
  ]
  memory-should-contain [
    <span class="Constant">2</span><span class="Special"> &lt;- </span><span class="Constant">1</span>  <span class="Comment"># cursor column</span>
    <span class="Constant">4</span><span class="Special"> &lt;- </span><span class="Constant">4</span>  <span class="Comment"># width*height</span>
    <span class="Constant">5</span><span class="Special"> &lt;- </span><span class="Constant">97</span>  <span class="Comment"># 'a'</span>
    <span class="Constant">6</span><span class="Special"> &lt;- </span><span class="Constant">7</span>  <span class="Comment"># white</span>
    <span class="Constant">7</span><span class="Special"> &lt;- </span><span class="Constant">99</span>  <span class="Comment"># 'c' over 'b'</span>
    <span class="Constant">8</span><span class="Special"> &lt;- </span><span class="Constant">7</span>  <span class="Comment"># white</span>
    <span class="Constant">9</span><span class="Special"> &lt;- </span><span class="Constant">0</span>
  ]
]

<span class="muScenario">scenario</span> print-newline-character [
  run [
<span class="CommentedCode">#?     $start-tracing #? 3</span>
    <span class="Constant">1</span>:address:screen<span class="Special"> &lt;- </span>new-fake-screen <span class="Constant">3/width</span>, <span class="Constant">2/height</span>
    <span class="Constant">1</span>:address:screen<span class="Special"> &lt;- </span>print-character <span class="Constant">1</span>:address:screen, <span class="Constant">97</span>  <span class="Comment"># 'a'</span>
    <span class="Constant">1</span>:address:screen<span class="Special"> &lt;- </span>print-character <span class="Constant">1</span>:address:screen, <span class="Constant">10/newline</span>
    <span class="Constant">2</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">1</span>:address:screen, cursor-row:offset
    <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">1</span>:address:screen, cursor-column:offset
    <span class="Constant">4</span>:address:array:screen-cell<span class="Special"> &lt;- </span>get *<span class="Constant">1</span>:address:screen, data:offset
    <span class="Constant">5</span>:array:screen-cell<span class="Special"> &lt;- </span>copy *<span class="Constant">4</span>:address:array:screen-cell
  ]
  memory-should-contain [
    <span class="Constant">2</span><span class="Special"> &lt;- </span><span class="Constant">1</span>  <span class="Comment"># cursor row</span>
    <span class="Constant">3</span><span class="Special"> &lt;- </span><span class="Constant">0</span>  <span class="Comment"># cursor column</span>
    <span class="Constant">5</span><span class="Special"> &lt;- </span><span class="Constant">6</span>  <span class="Comment"># width*height</span>
    <span class="Constant">6</span><span class="Special"> &lt;- </span><span class="Constant">97</span>  <span class="Comment"># 'a'</span>
    <span class="Constant">7</span><span class="Special"> &lt;- </span><span class="Constant">7</span>  <span class="Comment"># white</span>
    <span class="Constant">8</span><span class="Special"> &lt;- </span><span class="Constant">0</span>
  ]
]

<span class="muScenario">scenario</span> print-newline-at-bottom-line [
  run [
    <span class="Constant">1</span>:address:screen<span class="Special"> &lt;- </span>new-fake-screen <span class="Constant">3/width</span>, <span class="Constant">2/height</span>
    <span class="Constant">1</span>:address:screen<span class="Special"> &lt;- </span>print-character <span class="Constant">1</span>:address:screen, <span class="Constant">10/newline</span>
    <span class="Constant">1</span>:address:screen<span class="Special"> &lt;- </span>print-character <span class="Constant">1</span>:address:screen, <span class="Constant">10/newline</span>
    <span class="Constant">1</span>:address:screen<span class="Special"> &lt;- </span>print-character <span class="Constant">1</span>:address:screen, <span class="Constant">10/newline</span>
    <span class="Constant">2</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">1</span>:address:screen, cursor-row:offset
    <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">1</span>:address:screen, cursor-column:offset
  ]
  memory-should-contain [
    <span class="Constant">2</span><span class="Special"> &lt;- </span><span class="Constant">1</span>  <span class="Comment"># cursor row</span>
    <span class="Constant">3</span><span class="Special"> &lt;- </span><span class="Constant">0</span>  <span class="Comment"># cursor column</span>
  ]
]

<span class="muScenario">scenario</span> print-at-bottom-right [
  run [
    <span class="Constant">1</span>:address:screen<span class="Special"> &lt;- </span>new-fake-screen <span class="Constant">2/width</span>, <span class="Constant">2/height</span>
    <span class="Constant">1</span>:address:screen<span class="Special"> &lt;- </span>print-character <span class="Constant">1</span>:address:screen, <span class="Constant">10/newline</span>
    <span class="Constant">1</span>:address:screen<span class="Special"> &lt;- </span>print-character <span class="Constant">1</span>:address:screen, <span class="Constant">97</span>  <span class="Comment"># 'a'</span>
    <span class="Constant">1</span>:address:screen<span class="Special"> &lt;- </span>print-character <span class="Constant">1</span>:address:screen, <span class="Constant">98</span>  <span class="Comment"># 'b'</span>
    <span class="Constant">1</span>:address:screen<span class="Special"> &lt;- </span>print-character <span class="Constant">1</span>:address:screen, <span class="Constant">99</span>  <span class="Comment"># 'c'</span>
    <span class="Constant">1</span>:address:screen<span class="Special"> &lt;- </span>print-character <span class="Constant">1</span>:address:screen, <span class="Constant">10/newline</span>
    <span class="Constant">1</span>:address:screen<span class="Special"> &lt;- </span>print-character <span class="Constant">1</span>:address:screen, <span class="Constant">100</span>  <span class="Comment"># 'd'</span>
    <span class="Constant">2</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">1</span>:address:screen, cursor-row:offset
    <span class="Constant">3</span>:number<span class="Special"> &lt;- </span>get *<span class="Constant">1</span>:address:screen, cursor-column:offset
    <span class="Constant">4</span>:address:array:screen-cell<span class="Special"> &lt;- </span>get *<span class="Constant">1</span>:address:screen, data:offset
    <span class="Constant">5</span>:array:screen-cell<span class="Special"> &lt;- </span>copy *<span class="Constant">4</span>:address:array:screen-cell
  ]
  memory-should-contain [
    <span class="Constant">2</span><span class="Special"> &lt;- </span><span class="Constant">1</span>  <span class="Comment"># cursor row</span>
    <span class="Constant">3</span><span class="Special"> &lt;- </span><span class="Constant">1</span>  <span class="Comment"># cursor column</span>
    <span class="Constant">5</span><span class="Special"> &lt;- </span><span class="Constant">4</span>  <span class="Comment"># width*height</span>
    <span class="Constant">6</span><span class="Special"> &lt;- </span><span class="Constant">0</span>  <span class="Comment"># unused</span>
    <span class="Constant">7</span><span class="Special"> &lt;- </span><span class="Constant">7</span>  <span class="Comment"># white</span>
    <span class="Constant">8</span><span class="Special"> &lt;- </span><span class="Constant">0</span>  <span class="Comment"># unused</span>
    <span class="Constant">9</span><span class="Special"> &lt;- </span><span class="Constant">7</span>  <span class="Comment"># white</span>
    <span class="Constant">10</span><span class="Special"> &lt;- </span><span class="Constant">97</span> <span class="Comment"># 'a'</span>
    <span class="Constant">11</span><span class="Special"> &lt;- </span><span class="Constant">7</span>  <span class="Comment"># white</span>
    <span class="Constant">12</span><span class="Special"> &lt;- </span><span class="Constant">100</span>  <span class="Comment"># 'd' over 'b' and 'c' and newline</span>
    <span class="Constant">13</span><span class="Special"> &lt;- </span><span class="Constant">7</span>  <span class="Comment"># white</span>
    <span class="Constant">14</span><span class="Special"> &lt;- </span><span class="Constant">0</span>
  ]
]

<span class="muRecipe">recipe</span> clear-line [
  <span class="Constant">local-scope</span>
  sc:address:screen<span class="Special"> &lt;- </span><span class="Constant">next-ingredient</span>
  <span class="Comment"># if x exists, clear line in fake screen</span>
  <span class="Delimiter">{</span>
    <span class="muControl">break-unless</span> sc
    width:number<span class="Special"> &lt;- </span>get *sc, num-columns:offset
    column:address:number<span class="Special"> &lt;- </span>get-address *sc, cursor-column:offset
    original-column:number<span class="Special"> &lt;- </span>copy *column
    <span class="Comment"># space over the entire line</span>
<span class="CommentedCode">#?     $start-tracing #? 1</span>
    <span class="Delimiter">{</span>
<span class="CommentedCode">#?       $print *column, 10/newline</span>
      right:number<span class="Special"> &lt;- </span>subtract width, <span class="Constant">1</span>
      done?:boolean<span class="Special"> &lt;- </span>greater-or-equal *column, right
      <span class="muControl">break-if</span> done?
      print-character sc, <span class="Constant">[ ]</span>  <span class="Comment"># implicitly updates 'column'</span>
      <span class="muControl">loop</span>
    <span class="Delimiter">}</span>
    <span class="Comment"># now back to where the cursor was</span>
    *column<span class="Special"> &lt;- </span>copy original-column
    <span class="muControl">reply</span> sc/same-as-ingredient:<span class="Constant">0</span>
  <span class="Delimiter">}</span>
  <span class="Comment"># otherwise, real screen</span>
  clear-line-on-display
  <span class="muControl">reply</span> sc/same-as-ingredient:<span class="Constant">0</span>
]

<span class="muRecipe">recipe</span> cursor-position [
  <span class="Constant">local-scope</span>
  sc:address:screen<span class="Special"> &lt;- </span><span class="Constant">next-ingredient</span>
  <span class="Comment"># if x exists, lookup cursor in fake screen</span>
  <span class="Delimiter">{</span>
    <span class="muControl">break-unless</span> sc
    row:number<span class="Special"> &lt;- </span>get *sc, cursor-row:offset
    column:number<span class="Special"> &lt;- </span>get *sc, cursor-column:offset
    <span class="muControl">reply</span> row, column, sc/same-as-ingredient:<span class="Constant">0</span>
  <span class="Delimiter">}</span>
  row, column<span class="Special"> &lt;- </span>cursor-position-on-display
  <span class="muControl">reply</span> row, column, sc/same-as-ingredient:<span class="Constant">0</span>
]

<span class="muRecipe">recipe</span> move-cursor [
  <span class="Constant">local-scope</span>
  sc:address:screen<span class="Special"> &lt;- </span><span class="Constant">next-ingredient</span>
  new-row:number<span class="Special"> &lt;- </span><span class="Constant">next-ingredient</span>
  new-column:number<span class="Special"> &lt;- </span><span class="Constant">next-ingredient</span>
  <span class="Comment"># if x exists, move cursor in fake screen</span>
  <span class="Delimiter">{</span>
    <span class="muControl">break-unless</span> sc
    row:address:number<span class="Special"> &lt;- </span>get-address *sc, cursor-row:offset
    *row<span class="Special"> &lt;- </span>copy new-row
    column:address:number<span class="Special"> &lt;- </span>get-address *sc, cursor-column:offset
    *column<span class="Special"> &lt;- </span>copy new-column
    <span class="muControl">reply</span> sc/same-as-ingredient:<span class="Constant">0</span>
  <span class="Delimiter">}</span>
  <span class="Comment"># otherwise, real screen</span>
  move-cursor-on-display new-row, new-column
  <span class="muControl">reply</span> sc/same-as-ingredient:<span class="Constant">0</span>
]

<span class="muScenario">scenario</span> clear-line-erases-printed-characters [
  run [
<span class="CommentedCode">#?     $start-tracing #? 4</span>
    <span class="Constant">1</span>:address:screen<span class="Special"> &lt;- </span>new-fake-screen <span class="Constant">3/width</span>, <span class="Constant">2/height</span>
    <span class="Comment"># print a character</span>
    <span class="Constant">1</span>:address:screen<span class="Special"> &lt;- </span>print-character <span class="Constant">1</span>:address:screen, <span class="Constant">97</span>  <span class="Comment"># 'a'</span>
    <span class="Comment"># move cursor to start of line</span>
    <span class="Constant">1</span>:address:screen<span class="Special"> &lt;- </span>move-cursor <span class="Constant">1</span>:address:screen, <span class="Constant">0/row</span>, <span class="Constant">0/column</span>
    <span class="Comment"># clear line</span>
    <span class="Constant">1</span>:address:screen<span class="Special"> &lt;- </span>clear-line <span class="Constant">1</span>:address:screen
    <span class="Constant">2</span>:address:array:screen-cell<span class="Special"> &lt;- </span>get *<span class="Constant">1</span>:address:screen, data:offset
    <span class="Constant">3</span>:array:screen-cell<span class="Special"> &lt;- </span>copy *<span class="Constant">2</span>:address:array:screen-cell
  ]
  <span class="Comment"># screen should be blank</span>
  memory-should-contain [
    <span class="Constant">3</span><span class="Special"> &lt;- </span><span class="Constant">6</span>  <span class="Comment"># width*height</span>
    <span class="Constant">4</span><span class="Special"> &lt;- </span><span class="Constant">0</span>
    <span class="Constant">5</span><span class="Special"> &lt;- </span><span class="Constant">7</span>
    <span class="Constant">6</span><span class="Special"> &lt;- </span><span class="Constant">0</span>
    <span class="Constant">7</span><span class="Special"> &lt;- </span><span class="Constant">7</span>
    <span class="Constant">8</span><span class="Special"> &lt;- </span><span class="Constant">0</span>
    <span class="Constant">9</span><span class="Special"> &lt;- </span><span class="Constant">7</span>
    <span class="Constant">10</span><span class="Special"> &lt;- </span><span class="Constant">0</span>
    <span class="Constant">11</span><span class="Special"> &lt;- </span><span class="Constant">7</span>
    <span class="Constant">12</span><span class="Special"> &lt;- </span><span class="Constant">0</span>
    <span class="Constant">13</span><span class="Special"> &lt;- </span><span class="Constant">7</span>
    <span class="Constant">14</span><span class="Special"> &lt;- </span><span class="Constant">0</span>
    <span class="Constant">15</span><span class="Special"> &lt;- </span><span class="Constant">7</span>
  ]
]

<span class="muRecipe">recipe</span> cursor-down [
  <span class="Constant">local-scope</span>
  sc:address:screen<span class="Special"> &lt;- </span><span class="Constant">next-ingredient</span>
  <span class="Comment"># if x exists, move cursor in fake screen</span>
  <span class="Delimiter">{</span>
    <span class="muControl">break-unless</span> sc
    <span class="Delimiter">{</span>
      <span class="Comment"># if row &lt; height-1</span>
      height:number<span class="Special"> &lt;- </span>get *sc, num-rows:offset
      row:address:number<span class="Special"> &lt;- </span>get-address *sc, cursor-row:offset
      max:number<span class="Special"> &lt;- </span>subtract height, <span class="Constant">1</span>
      at-bottom?:boolean<span class="Special"> &lt;- </span>greater-or-equal *row, max
      <span class="muControl">break-if</span> at-bottom?
      <span class="Comment"># row = row+1</span>
      *row<span class="Special"> &lt;- </span>add *row, <span class="Constant">1</span>
    <span class="Delimiter">}</span>
    <span class="muControl">reply</span> sc/same-as-ingredient:<span class="Constant">0</span>
  <span class="Delimiter">}</span>
  <span class="Comment"># otherwise, real screen</span>
  move-cursor-down-on-display
  <span class="muControl">reply</span> sc/same-as-ingredient:<span class="Constant">0</span>
]

<span class="muRecipe">recipe</span> cursor-up [
  <span class="Constant">local-scope</span>
  sc:address:screen<span class="Special"> &lt;- </span><span class="Constant">next-ingredient</span>
  <span class="Comment"># if x exists, move cursor in fake screen</span>
  <span class="Delimiter">{</span>
    <span class="muControl">break-unless</span> sc
    <span class="Delimiter">{</span>
      <span class="Comment"># if row &gt; 0</span>
      row:address:number<span class="Special"> &lt;- </span>get-address *sc, cursor-row:offset
      at-top?:boolean<span class="Special"> &lt;- </span>lesser-or-equal *row, <span class="Constant">0</span>
      <span class="muControl">break-if</span> at-top?
      <span class="Comment"># row = row-1</span>
      *row<span class="Special"> &lt;- </span>subtract *row, <span class="Constant">1</span>
    <span class="Delimiter">}</span>
    <span class="muControl">reply</span> sc/same-as-ingredient:<span class="Constant">0</span>
  <span class="Delimiter">}</span>
  <span class="Comment"># otherwise, real screen</span>
  move-cursor-up-on-display
  <span class="muControl">reply</span> sc/same-as-ingredient:<span class="Constant">0</span>
]

<span class="muRecipe">recipe</span> cursor-right [
  <span class="Constant">local-scope</span>
  sc:address:screen<span class="Special"> &lt;- </span><span class="Constant">next-ingredient</span>
  <span class="Comment"># if x exists, move cursor in fake screen</span>
  <span class="Delimiter">{</span>
    <span class="muControl">break-unless</span> sc
    <span class="Delimiter">{</span>
      <span class="Comment"># if column &lt; width-1</span>
      width:number<span class="Special"> &lt;- </span>get *sc, num-columns:offset
      column:address:number<span class="Special"> &lt;- </span>get-address *sc, cursor-column:offset
      max:number<span class="Special"> &lt;- </span>subtract width, <span class="Constant">1</span>
      at-bottom?:boolean<span class="Special"> &lt;- </span>greater-or-equal *column, max
      <span class="muControl">break-if</span> at-bottom?
      <span class="Comment"># column = column+1</span>
      *column<span class="Special"> &lt;- </span>add *column, <span class="Constant">1</span>
    <span class="Delimiter">}</span>
    <span class="muControl">reply</span> sc/same-as-ingredient:<span class="Constant">0</span>
  <span class="Delimiter">}</span>
  <span class="Comment"># otherwise, real screen</span>
  move-cursor-right-on-display
  <span class="muControl">reply</span> sc/same-as-ingredient:<span class="Constant">0</span>
]

<span class="muRecipe">recipe</span> cursor-left [
  <span class="Constant">local-scope</span>
  sc:address:screen<span class="Special"> &lt;- </span><span class="Constant">next-ingredient</span>
  <span class="Comment"># if x exists, move cursor in fake screen</span>
  <span class="Delimiter">{</span>
    <span class="muControl">break-unless</span> sc
    <span class="Delimiter">{</span>
      <span class="Comment"># if column &gt; 0</span>
      column:address:number<span class="Special"> &lt;- </span>get-address *sc, cursor-column:offset
      at-top?:boolean<span class="Special"> &lt;- </span>lesser-or-equal *column, <span class="Constant">0</span>
      <span class="muControl">break-if</span> at-top?
      <span class="Comment"># column = column-1</span>
      *column<span class="Special"> &lt;- </span>subtract *column, <span class="Constant">1</span>
    <span class="Delimiter">}</span>
    <span class="muControl">reply</span> sc/same-as-ingredient:<span class="Constant">0</span>
  <span class="Delimiter">}</span>
  <span class="Comment"># otherwise, real screen</span>
  move-cursor-left-on-display
  <span class="muControl">reply</span> sc/same-as-ingredient:<span class="Constant">0</span>
]

<span class="muRecipe">recipe</span> cursor-to-start-of-line [
  <span class="Constant">local-scope</span>
  sc:address:screen<span class="Special"> &lt;- </span><span class="Constant">next-ingredient</span>
  row:number, _, sc<span class="Special"> &lt;- </span>cursor-position sc
  column:number<span class="Special"> &lt;- </span>copy <span class="Constant">0</span>
  sc<span class="Special"> &lt;- </span>move-cursor sc, row, column
  <span class="muControl">reply</span> sc/same-as-ingredient:<span class="Constant">0</span>
]

<span class="muRecipe">recipe</span> cursor-to-next-line [
  <span class="Constant">local-scope</span>
  screen:address<span class="Special"> &lt;- </span><span class="Constant">next-ingredient</span>
  screen<span class="Special"> &lt;- </span>cursor-down screen
  screen<span class="Special"> &lt;- </span>cursor-to-start-of-line screen
  <span class="muControl">reply</span> screen/same-as-ingredient:<span class="Constant">0</span>
]

<span class="muRecipe">recipe</span> screen-width [
  <span class="Constant">local-scope</span>
  sc:address:screen<span class="Special"> &lt;- </span><span class="Constant">next-ingredient</span>
  <span class="Comment"># if x exists, move cursor in fake screen</span>
  <span class="Delimiter">{</span>
    <span class="muControl">break-unless</span> sc
    width:number<span class="Special"> &lt;- </span>get *sc, num-columns:offset
    <span class="muControl">reply</span> width
  <span class="Delimiter">}</span>
  <span class="Comment"># otherwise, real screen</span>
  width:number<span class="Special"> &lt;- </span>display-width
  <span class="muControl">reply</span> width
]

<span class="muRecipe">recipe</span> screen-height [
  <span class="Constant">local-scope</span>
  sc:address:screen<span class="Special"> &lt;- </span><span class="Constant">next-ingredient</span>
  <span class="Comment"># if x exists, move cursor in fake screen</span>
  <span class="Delimiter">{</span>
    <span class="muControl">break-unless</span> sc
    height:number<span class="Special"> &lt;- </span>get *sc, num-rows:offset
    <span class="muControl">reply</span> height
  <span class="Delimiter">}</span>
  <span class="Comment"># otherwise, real screen</span>
  height:number<span class="Special"> &lt;- </span>display-height
  <span class="muControl">reply</span> height
]

<span class="muRecipe">recipe</span> hide-cursor [
  <span class="Constant">local-scope</span>
  screen:address<span class="Special"> &lt;- </span><span class="Constant">next-ingredient</span>
  <span class="Comment"># if x exists (not real display), do nothing</span>
  <span class="Delimiter">{</span>
    <span class="muControl">break-unless</span> screen
    <span class="muControl">reply</span> screen
  <span class="Delimiter">}</span>
  <span class="Comment"># otherwise, real screen</span>
  hide-cursor-on-display
  <span class="muControl">reply</span> screen
]

<span class="muRecipe">recipe</span> show-cursor [
  <span class="Constant">local-scope</span>
  screen:address<span class="Special"> &lt;- </span><span class="Constant">next-ingredient</span>
  <span class="Comment"># if x exists (not real display), do nothing</span>
  <span class="Delimiter">{</span>
    <span class="muControl">break-unless</span> screen
    <span class="muControl">reply</span> screen
  <span class="Delimiter">}</span>
  <span class="Comment"># otherwise, real screen</span>
  show-cursor-on-display
  <span class="muControl">reply</span> screen
]

<span class="muRecipe">recipe</span> hide-screen [
  <span class="Constant">local-scope</span>
  screen:address<span class="Special"> &lt;- </span><span class="Constant">next-ingredient</span>
  <span class="Comment"># if x exists (not real display), do nothing</span>
  <span class="Delimiter">{</span>
    <span class="muControl">break-unless</span> screen
    <span class="muControl">reply</span> screen
  <span class="Delimiter">}</span>
  <span class="Comment"># otherwise, real screen</span>
  hide-display
  <span class="muControl">reply</span> screen
]

<span class="muRecipe">recipe</span> show-screen [
  <span class="Constant">local-scope</span>
  screen:address<span class="Special"> &lt;- </span><span class="Constant">next-ingredient</span>
  <span class="Comment"># if x exists (not real display), do nothing</span>
  <span class="Delimiter">{</span>
    <span class="muControl">break-unless</span> screen
    <span class="muControl">reply</span> screen
  <span class="Delimiter">}</span>
  <span class="Comment"># otherwise, real screen</span>
  show-display
  <span class="muControl">reply</span> screen
]

<span class="muRecipe">recipe</span> print-string [
  <span class="Constant">local-scope</span>
  screen:address<span class="Special"> &lt;- </span><span class="Constant">next-ingredient</span>
  s:address:array:character<span class="Special"> &lt;- </span><span class="Constant">next-ingredient</span>
  color:number, color-found?:boolean<span class="Special"> &lt;- </span><span class="Constant">next-ingredient</span>
  <span class="Delimiter">{</span>
    <span class="Comment"># default color to white</span>
    <span class="muControl">break-if</span> color-found?
    color<span class="Special"> &lt;- </span>copy <span class="Constant">7/white</span>
  <span class="Delimiter">}</span>
  bg-color:number, bg-color-found?:boolean<span class="Special"> &lt;- </span><span class="Constant">next-ingredient</span>
  <span class="Delimiter">{</span>
    <span class="Comment"># default bg-color to black</span>
    <span class="muControl">break-if</span> bg-color-found?
    bg-color<span class="Special"> &lt;- </span>copy <span class="Constant">0/black</span>
  <span class="Delimiter">}</span>
  len:number<span class="Special"> &lt;- </span>length *s
  i:number<span class="Special"> &lt;- </span>copy <span class="Constant">0</span>
  <span class="Delimiter">{</span>
    done?:boolean<span class="Special"> &lt;- </span>greater-or-equal i, len
    <span class="muControl">break-if</span> done?
    c:character<span class="Special"> &lt;- </span>index *s, i
    print-character screen, c, color, bg-color
    i<span class="Special"> &lt;- </span>add i, <span class="Constant">1</span>
    <span class="muControl">loop</span>
  <span class="Delimiter">}</span>
  <span class="muControl">reply</span> screen/same-as-ingredient:<span class="Constant">0</span>
]

<span class="muScenario">scenario</span> print-string-stops-at-right-margin [
  run [
    <span class="Constant">1</span>:address:screen<span class="Special"> &lt;- </span>new-fake-screen <span class="Constant">3/width</span>, <span class="Constant">2/height</span>
    <span class="Constant">2</span>:address:array:character<span class="Special"> &lt;- </span>new <span class="Constant">[abcd]</span>
    <span class="Constant">1</span>:address:screen<span class="Special"> &lt;- </span>print-string <span class="Constant">1</span>:address:screen, <span class="Constant">2</span>:address:array:character
    <span class="Constant">3</span>:address:array:screen-cell<span class="Special"> &lt;- </span>get *<span class="Constant">1</span>:address:screen, data:offset
    <span class="Constant">4</span>:array:screen-cell<span class="Special"> &lt;- </span>copy *<span class="Constant">3</span>:address:array:screen-cell
  ]
  memory-should-contain [
    <span class="Constant">4</span><span class="Special"> &lt;- </span><span class="Constant">6</span>  <span class="Comment"># width*height</span>
    <span class="Constant">5</span><span class="Special"> &lt;- </span><span class="Constant">97</span>  <span class="Comment"># 'a'</span>
    <span class="Constant">6</span><span class="Special"> &lt;- </span><span class="Constant">7</span>  <span class="Comment"># white</span>
    <span class="Constant">7</span><span class="Special"> &lt;- </span><span class="Constant">98</span>  <span class="Comment"># 'b'</span>
    <span class="Constant">8</span><span class="Special"> &lt;- </span><span class="Constant">7</span>  <span class="Comment"># white</span>
    <span class="Constant">9</span><span class="Special"> &lt;- </span><span class="Constant">100</span>  <span class="Comment"># 'd' overwrites 'c'</span>
    <span class="Constant">10</span><span class="Special"> &lt;- </span><span class="Constant">7</span>  <span class="Comment"># white</span>
    <span class="Constant">11</span><span class="Special"> &lt;- </span><span class="Constant">0</span>  <span class="Comment"># unused</span>
  ]
]

<span class="muRecipe">recipe</span> print-integer [
  <span class="Constant">local-scope</span>
  screen:address<span class="Special"> &lt;- </span><span class="Constant">next-ingredient</span>
  n:number<span class="Special"> &lt;- </span><span class="Constant">next-ingredient</span>
  color:number, color-found?:boolean<span class="Special"> &lt;- </span><span class="Constant">next-ingredient</span>
  <span class="Delimiter">{</span>
    <span class="Comment"># default color to white</span>
    <span class="muControl">break-if</span> color-found?
    color<span class="Special"> &lt;- </span>copy <span class="Constant">7/white</span>
  <span class="Delimiter">}</span>
  bg-color:number, bg-color-found?:boolean<span class="Special"> &lt;- </span><span class="Constant">next-ingredient</span>
  <span class="Delimiter">{</span>
    <span class="Comment"># default bg-color to black</span>
    <span class="muControl">break-if</span> bg-color-found?
    bg-color<span class="Special"> &lt;- </span>copy <span class="Constant">0/black</span>
  <span class="Delimiter">}</span>
  <span class="Comment"># todo: other bases besides decimal</span>
  s:address:array:character<span class="Special"> &lt;- </span>integer-to-decimal-string n
  print-string screen, s, color, bg-color
  <span class="muControl">reply</span> screen/same-as-ingredient:<span class="Constant">0</span>
]
</pre>
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