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
*	5485 - promote SubX to top-level	Kartik Agaram	2019-07-27	1	-0/+0

<!DOCTYPE html> <html> <head> <meta charset="UTF-8"> <title>Mu - 101screen.subx</title> <meta name="Generator" content="Vim/8.2"> <meta name="plugin-version" content="vim8.1_v2"> <meta name="syntax" content="none"> <meta name="settings" content="number_lines,use_css,pre_wrap,no_foldcolumn,expand_tabs,line_ids,prevent_copy=,use_input_for_pc=fallback"> <meta name="colorscheme" content="minimal-light"> <style>  </style> <script>  </script> </head> <body onload='JumpToLine();'> <a href='https://github.com/akkartik/mu/blob/main/101screen.subx'>https://github.com/akkartik/mu/blob/main/101screen.subx</a> <pre id='vimCodeElement'> 1 # Primitives for screen control. 2 # 3 # We need to do this in machine code because Mu doesn't have global variables 4 # yet (for the start of video memory). 5 6 == code 7 8 pixel-on-real-screen: # x: int, y: int, color: int 9 # . prologue 10 55/push-ebp 11 89/<- %ebp 4/r32/esp 12 # 13 (<a href='101screen.subx.html#L21'>pixel-on-screen-buffer</a> *<a href='boot.subx.html#L651'>Video-memory-addr</a> *(ebp+8) *(ebp+0xc) *(ebp+0x10) 0x400 0x300) 14 $pixel-on-real-screen:end: 15 # . epilogue 16 89/<- %esp 5/r32/ebp 17 5d/pop-to-ebp 18 c3/return 19 20 # 'buffer' here is not a valid Mu type: a naked address without a length. 21 pixel-on-screen-buffer: # buffer: (addr byte), x: int, y: int, color: int, width: int, height: int 22 # . prologue 23 55/push-ebp 24 89/<- %ebp 4/r32/esp 25 # . save registers 26 50/push-eax 27 51/push-ecx 28 # bounds checks 29 8b/-> *(ebp+0xc) 0/r32/eax # foo 30 3d/compare-eax-and 0/imm32 31 7c/jump-if-< $pixel-on-screen-buffer:end/disp8 32 3b/compare 0/r32/eax *(ebp+0x18) 33 7d/jump-if->= $pixel-on-screen-buffer:end/disp8 34 8b/-> *(ebp+0x10) 0/r32/eax 35 3d/compare-eax-and 0/imm32 36 7c/jump-if-< $pixel-on-screen-buffer:end/disp8 37 3b/compare 0/r32/eax *(ebp+0x1c) 38 7d/jump-if->= $pixel-on-screen-buffer:end/disp8 39 # eax = y*width + x 40 8b/-> *(ebp+0x10) 0/r32/eax 41 0f af/multiply-> *(ebp+0x18) 0/r32/eax 42 03/add-> *(ebp+0xc) 0/r32/eax 43 # eax += location of frame buffer 44 03/add-> *(ebp+8) 0/r32/eax 45 # *eax = color 46 8b/-> *(ebp+0x14) 1/r32/ecx 47 88/byte<- *eax 1/r32/CL 48 $pixel-on-screen-buffer:end: 49 # . restore registers 50 59/pop-to-ecx 51 58/pop-to-eax 52 # . epilogue 53 89/<- %esp 5/r32/ebp 54 5d/pop-to-ebp 55 c3/return </pre> </body> </html>