mu - Soul of a tiny new machine. More thorough tests → More comprehensible and rewrite-friendly software → More resilient society.

	Commit message (Expand)	Author	Age	Files	Lines
*	1276 - make C++ version the default	Kartik K. Agaram	2015-05-05	1	-0/+12

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd"> <html> <head> <meta http-equiv="content-type" content="text/html; charset=UTF-8"> <title>Mu - 103grapheme.subx</title> <meta name="Generator" content="Vim/8.1"> <meta name="plugin-version" content="vim8.1_v1"> <meta name="syntax" content="none"> <meta name="settings" content="number_lines,use_css,pre_wrap,no_foldcolumn,expand_tabs,line_ids,prevent_copy="> <meta name="colorscheme" content="minimal-dark"> <style type="text/css">  </style> <script type='text/javascript'>  </script> </head> <body onload='JumpToLine();'> <a href='https://github.com/akkartik/mu/blob/main/103grapheme.subx'>https://github.com/akkartik/mu/blob/main/103grapheme.subx</a> <pre id='vimCodeElement'> 1 # Use the built-in font to draw a grapheme to real screen. 2 # 3 # We need to do this in machine code because Mu doesn't have global variables 4 # yet (for the start of the font). 5 # 6 # There are uncomfortable assumptions baked in here about english/latin 7 # script. We convert the grid of pixels into a fixed-width grid of graphemes, 8 # which may not work well with other language families. 9 10 == code 11 12 # The Mu computer's screen is 1024px wide and 768px tall. 13 # The Mu computer's font is 8px wide and 16px tall. 14 # Therefore 'x' here is in [0, 128), and 'y' is in [0, 48) 15 # Doesn't update the cursor; where the cursor should go after printing the 16 # current grapheme is a higher-level concern. 17 draw-grapheme-on-real-screen: # g: grapheme, x: int, y: int, color: int, background-color: int 18 # . prologue 19 55/push-ebp 20 89/<- %ebp 4/r32/esp 21 # . save registers 22 50/push-eax 23 51/push-ecx 24 52/push-edx 25 53/push-ebx 26 56/push-esi 27 # var letter-bitmap/esi = font[g] 28 8b/-> *(ebp+8) 6/r32/esi 29 c1 4/subop/shift-left %esi 4/imm8 30 81 0/subop/add %esi <a href='boot.subx.html#L643'>Font</a>/imm32 31 # if (letter-bitmap >= 0x9400) return # characters beyond ASCII currently not supported 32 81 7/subop/compare %esi 0x9400/imm32 33 7d/jump-if->= $draw-grapheme-on-real-screen:end/disp8 34 # var ycurr/edx: int = y*16 35 8b/-> *(ebp+0x10) 2/r32/edx 36 c1 4/subop/shift-left %edx 4/imm8 37 # var ymax/ebx: int = ycurr + 16 38 8b/-> *(ebp+0x10) 3/r32/ebx 39 c1 4/subop/shift-left %ebx 4/imm8 40 81 0/subop/add %ebx 0x10/imm32 41 { 42 # if (ycurr >= ymax) break 43 39/compare %edx 3/r32/ebx 44 7d/jump-if->= break/disp8 45 # var xcurr/eax: int = x*8 + 7 46 8b/-> *(ebp+0xc) 0/r32/eax # font-width - 1 47 c1 4/subop/shift-left %eax 3/imm8 48 81 0/subop/add %eax 7/imm32 49 # var xmin/ecx: int = x*8 50 8b/-> *(ebp+0xc) 1/r32/ecx 51 c1 4/subop/shift-left %ecx 3/imm8 52 # var row-bitmap/ebx: int = *letter-bitmap 53 53/push-ebx 54 8b/-> *esi 3/r32/ebx 55 { 56 # if (xcurr < xmin) break 57 39/compare %eax 1/r32/ecx 58 7c/jump-if-< break/disp8 59 # shift LSB from row-bitmap into carry flag (CF) 60 c1 5/subop/shift-right-logical %ebx 1/imm8 61 # if LSB, draw a pixel in the given color 62 { 63 73/jump-if-not-CF break/disp8 64 (<a href='101screen.subx.html#L8'>pixel-on-real-screen</a> %eax %edx *(ebp+0x14)) 65 eb/jump $draw-grapheme-on-real-screen:continue/disp8 66 } 67 # otherwise use the background color 68 (<a href='101screen.subx.html#L8'>pixel-on-real-screen</a> %eax %edx *(ebp+0x18)) 69 $draw-grapheme-on-real-screen:continue: 70 # --x 71 48/decrement-eax 72 # 73 eb/jump loop/disp8 74 } 75 # reclaim row-bitmap 76 5b/pop-to-ebx 77 # ++y 78 42/increment-edx 79 # next bitmap row 80 46/increment-esi 81 # 82 eb/jump loop/disp8 83 } 84 $draw-grapheme-on-real-screen:end: 85 # . restore registers 86 5e/pop-to-esi 87 5b/pop-to-ebx 88 5a/pop-to-edx 89 59/pop-to-ecx 90 58/pop-to-eax 91 # . epilogue 92 89/<- %esp 5/r32/ebp 93 5d/pop-to-ebp 94 c3/return 95 96 cursor-position-on-real-screen: # -> _/eax: int, _/ecx: int 97 # . prologue 98 55/push-ebp 99 89/<- %ebp 4/r32/esp 100 # TODO: support fake screen; we currently assume 'screen' is always 0 (real) 101 8b/-> *<a href='103grapheme.subx.html#L170'>Real-screen-cursor-x</a> 0/r32/eax 102 8b/-> *<a href='103grapheme.subx.html#L172'>Real-screen-cursor-y</a> 1/r32/ecx 103 $cursor-position-on-real-screen:end: 104 # . epilogue 105 89/<- %esp 5/r32/ebp 106 5d/pop-to-ebp 107 c3/return 108 109 set-cursor-position-on-real-screen: # x: int, y: int 110 # . prologue 111 55/push-ebp 112 89/<- %ebp 4/r32/esp 113 # . save registers 114 50/push-eax 115 # 116 8b/-> *(ebp+8) 0/r32/eax 117 89/<- *<a href='103grapheme.subx.html#L170'>Real-screen-cursor-x</a> 0/r32/eax 118 8b/-> *(ebp+0xc) 0/r32/eax 119 89/<- *<a href='103grapheme.subx.html#L172'>Real-screen-cursor-y</a> 0/r32/eax 120 $set-cursor-position-on-real-screen:end: 121 # . restore registers 122 58/pop-to-eax 123 # . epilogue 124 89/<- %esp 5/r32/ebp 125 5d/pop-to-ebp 126 c3/return 127 128 # Not a real `show-cursor` primitive: 129 # - does not clear previous location cursor was shown at. 130 # - does not preserve what was at the cursor. Caller is responsible for 131 # tracking what was on the screen at this position before and passing it 132 # in again. 133 # - does not stop showing the cursor at this location when the cursor moves 134 draw-cursor-on-real-screen: # g: grapheme 135 # . prologue 136 55/push-ebp 137 89/<- %ebp 4/r32/esp 138 # . save registers 139 50/push-eax 140 51/push-ecx 141 # 142 (<a href='103grapheme.subx.html#L96'>cursor-position-on-real-screen</a>) # => eax, ecx 143 (<a href='103grapheme.subx.html#L17'>draw-grapheme-on-real-screen</a> *(ebp+8) %eax %ecx 0 7) 144 $draw-cursor-on-real-screen:end: 145 # . restore registers 146 59/pop-to-ecx 147 58/pop-to-eax 148 # . epilogue 149 89/<- %esp 5/r32/ebp 150 5d/pop-to-ebp 151 c3/return 152 153 == data 154 155 # The cursor is where certain Mu functions (usually of the form 156 # 'draw*cursor*') print to by default. 157 # 158 # We don't bother displaying the cursor when drawing. It only becomes visible 159 # on draw-cursor, which is quite rickety (see above) 160 # 161 # It's up to applications to manage cursor display: 162 # - clean up where it used to be 163 # - display the cursor before waiting for a key 164 # - ensure its location appropriately suggests the effect keystrokes will have 165 # - ensure its contents (and colors) appropriately reflect the state of the 166 # screen 167 # 168 # There's no blinking, etc. We aren't using any hardware-supported text mode 169 # here. 170 Real-screen-cursor-x: 171 0/imm32 172 Real-screen-cursor-y: 173 0/imm32 </pre> </body> </html>