.

1 files changed, 44 insertions, 59 deletions

diff --git a/500fake-screen.mu b/500fake-screen.mu
index 1d13f2cf..43f6152c 100644
--- a/500fake-screen.mu
+++ b/500fake-screen.mu
@@ -18,10 +18,8 @@ type screen {
   data: (handle array screen-cell)
   cursor-x: int  # [0..width)
   cursor-y: int  # [0..height)
-  invalid-cell-index: int
   # pixel graphics
   pixels: (handle array byte)
-  invalid-pixel-index: int
 }
 
 type screen-cell {
@@ -48,14 +46,10 @@ fn initialize-screen _screen: (addr screen), width: int, height: int, pixel-grap
     var data-ah/edi: (addr handle array screen-cell) <- get screen, data
     var capacity/eax: int <- copy width
     capacity <- multiply height
-    # add 1 for sentinel
-    capacity <- increment
     #
     populate data-ah, capacity
     # save sentinel index
     capacity <- decrement
-    var dest/ecx: (addr int) <- get screen, invalid-cell-index
-    copy-to *dest, capacity
   }
   # if necessary, populate screen->pixels
   {
@@ -66,14 +60,10 @@ fn initialize-screen _screen: (addr screen), width: int, height: int, pixel-grap
     capacity <- shift-left 3/log2-font-width
     capacity <- multiply height
     capacity <- shift-left 4/log2-font-height
-    # add 1 for sentinel
-    capacity <- increment
     #
     populate pixels-ah, capacity
     # save sentinel index
     capacity <- decrement
-    var dest/ecx: (addr int) <- get screen, invalid-pixel-index
-    copy-to *dest, capacity
   }
   # screen->cursor-x = 0
   dest <- get screen, cursor-x
@@ -111,6 +101,32 @@ fn draw-grapheme _screen: (addr screen), g: grapheme, x: int, y: int, color: int
     return
   }
   # fake screen
+  # ignore if out of bounds
+  {
+    compare x, 0
+    break-if->=
+    return
+  }
+  {
+    var xmax/eax: (addr int) <- get screen, width
+    var xcurr/ecx: int <- copy x
+    compare xcurr, *xmax
+    break-if-<
+    return
+  }
+  {
+    compare y, 0
+    break-if->=
+    return
+  }
+  {
+    var ymax/eax: (addr int) <- get screen, height
+    var ycurr/ecx: int <- copy y
+    compare ycurr, *ymax
+    break-if-<
+    return
+  }
+  #
   var index/ecx: int <- screen-cell-index screen, x, y
   var data-ah/eax: (addr handle array screen-cell) <- get screen, data
   var data/eax: (addr array screen-cell) <- lookup *data-ah
@@ -136,35 +152,6 @@ fn draw-code-point screen: (addr screen), c: code-point, x: int, y: int, color:
 # fake screens only
 fn screen-cell-index _screen: (addr screen), x: int, y: int -> _/ecx: int {
   var screen/esi: (addr screen) <- copy _screen
-  # if out of bounds, silently return a pixel that's never checked
-  {
-    compare x, 0
-    break-if->=
-    var invalid/eax: (addr int) <- get screen, invalid-cell-index
-    return *invalid
-  }
-  {
-    var xmax/eax: (addr int) <- get screen, width
-    var xcurr/ecx: int <- copy x
-    compare xcurr, *xmax
-    break-if-<
-    var invalid/eax: (addr int) <- get screen, invalid-cell-index
-    return *invalid
-  }
-  {
-    compare y, 0
-    break-if->=
-    var invalid/eax: (addr int) <- get screen, invalid-cell-index
-    return *invalid
-  }
-  {
-    var ymax/eax: (addr int) <- get screen, height
-    var ycurr/ecx: int <- copy y
-    compare ycurr, *ymax
-    break-if-<
-    var invalid/eax: (addr int) <- get screen, invalid-cell-index
-    return *invalid
-  }
   var width-addr/eax: (addr int) <- get screen, width
   var result/ecx: int <- copy y
   result <- multiply *width-addr
@@ -515,44 +502,42 @@ fn pixel screen: (addr screen), x: int, y: int, color: int {
     break-if-!=
     abort "pixel graphics not enabled for this screen"
   }
-  var index/ecx: int <- pixel-index screen, x, y
-  var dest/ecx: (addr byte) <- index pixels, index
-  var src/eax: byte <- copy-byte color
-  copy-byte-to *dest, src
-}
-
-fn pixel-index _screen: (addr screen), x: int, y: int -> _/ecx: int {
-  var screen/esi: (addr screen) <- copy _screen
+  # ignore if out of bounds
   {
     compare x, 0
     break-if->=
-    var invalid/eax: (addr int) <- get screen, invalid-pixel-index
-    return *invalid
+    return
   }
   {
-    var xmax-a/eax: (addr int) <- get screen, width
-    var xmax/eax: int <- copy *xmax-a
+    var xmax-addr/eax: (addr int) <- get screen, width
+    var xmax/eax: int <- copy *xmax-addr
     xmax <- shift-left 3/log2-font-width
     compare x, xmax
     break-if-<
-    var invalid/eax: (addr int) <- get screen, invalid-pixel-index
-    return *invalid
+    return
   }
   {
     compare y, 0
     break-if->=
-    var invalid/eax: (addr int) <- get screen, invalid-pixel-index
-    return *invalid
+    return
   }
   {
-    var ymax-a/eax: (addr int) <- get screen, height
-    var ymax/eax: int <- copy *ymax-a
+    var ymax-addr/eax: (addr int) <- get screen, height
+    var ymax/eax: int <- copy *ymax-addr
     ymax <- shift-left 4/log2-font-height
     compare y, ymax
     break-if-<
-    var invalid/eax: (addr int) <- get screen, invalid-pixel-index
-    return *invalid
+    return
   }
+  #
+  var index/ecx: int <- pixel-index screen, x, y
+  var dest/ecx: (addr byte) <- index pixels, index
+  var src/eax: byte <- copy-byte color
+  copy-byte-to *dest, src
+}
+
+fn pixel-index _screen: (addr screen), x: int, y: int -> _/ecx: int {
+  var screen/esi: (addr screen) <- copy _screen
   var width-addr/eax: (addr int) <- get screen, width
   var result/ecx: int <- copy y
   result <- multiply *width-addr