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Diffstat (limited to 'demos/3rdparty/doom/README.asm')
| -rw-r--r-- | demos/3rdparty/doom/README.asm | 283 |
1 files changed, 0 insertions, 283 deletions
diff --git a/demos/3rdparty/doom/README.asm b/demos/3rdparty/doom/README.asm deleted file mode 100644 index 89629769..00000000 --- a/demos/3rdparty/doom/README.asm +++ /dev/null @@ -1,283 +0,0 @@ - -README - DOOM assembly code - -Okay, I add the DOS assembly module for the historically -inclined here (may rec.games.programmer suffer). If anyone -feels the urge to port these to GNU GCC; either inline or -as separate modules including Makefile support, be my guest. - -Module tmap.S includes the inner loops for texture mapping, -the interesting one being the floor/ceiling span rendering. - -There was another module in the source dump, fpfunc.S, that -had both texture mapping and fixed point functions. It -contained implementations both for i386 and M68k. For -brevity, I include only the i386 fixed point stuff below. - -//==================================================== -// tmap.S as of January 10th, 1997 - -//================ -// -// R_DrawColumn -// -//================ - - .data -loopcount .long 0 -pixelcount .long 0 - - .text - - .align 16 -.globl _R_DrawColumn -_R_DrawColumn: - - pushad - - movl ebp,[_dc_yl] - movl ebx,ebp - movl edi,[_ylookup+ebx*4] - movl ebx,[_dc_x] - addl edi,[_columnofs + ebx*4] - - movl eax,[_dc_yh] - incl eax - subl eax,ebp // pixel count - movl [pixelcount],eax // save for final pixel - js done // nothing to scale - shrl eax,1 // double pixel count - movl [loopcount],eax - - movl ecx,[_dc_iscale] - - movl eax,[_centery] - subl eax,ebp - imull ecx - movl ebp,[_dc_texturemid] - subl ebp,eax - shll ebp,9 // 7 significant bits, 25 frac - - movl esi,[_dc_source] - - - movl ebx,[_dc_iscale] - shll ebx,9 - movl eax,OFFSET patch1+2 // convice tasm to modify code... - movl [eax],ebx - movl eax,OFFSET patch2+2 // convice tasm to modify code... - movl [eax],ebx - -// eax aligned colormap -// ebx aligned colormap -// ecx,edx scratch -// esi virtual source -// edi moving destination pointer -// ebp frac - - movl ecx,ebp // begin calculating first pixel - addl ebp,ebx // advance frac pointer - shrl ecx,25 // finish calculation for first pixel - movl edx,ebp // begin calculating second pixel - addl ebp,ebx // advance frac pointer - shrl edx,25 // finish calculation for second pixel - movl eax,[_dc_colormap] - movl ebx,eax - movb al,[esi+ecx] // get first pixel - movb bl,[esi+edx] // get second pixel - movb al,[eax] // color translate first pixel - movb bl,[ebx] // color translate second pixel - - testl [pixelcount],0fffffffeh - jnz doubleloop // at least two pixels to map - jmp checklast - - .align 16 -doubleloop: - movl ecx,ebp // begin calculating third pixel -patch1: - addl ebp,12345678h // advance frac pointer - movb [edi],al // write first pixel - shrl ecx,25 // finish calculation for third pixel - movl edx,ebp // begin calculating fourth pixel -patch2: - addl ebp,12345678h // advance frac pointer - movl [edi+SCREENWIDTH],bl // write second pixel - shrl edx,25 // finish calculation for fourth pixel - movb al,[esi+ecx] // get third pixel - addl edi,SCREENWIDTH*2 // advance to third pixel destination - movb bl,[esi+edx] // get fourth pixel - decl [loopcount] // done with loop? - movb al,[eax] // color translate third pixel - movb bl,[ebx] // color translate fourth pixel - jnz doubleloop - -// check for final pixel -checklast: - testl [pixelcount],1 - jz done - movb [edi],al // write final pixel - -done: - popad - ret - - - -//================ -// -// R_DrawSpan -// -// Horizontal texture mapping -// -//================ - - - .align 16 -.globl _R_DrawSpan -_R_DrawSpan: - pushad - -// -// find loop count -// - movl eax,[_ds_x2] - incl eax - subl eax,[_ds_x1] // pixel count - movl [pixelcount],eax // save for final pixel - js hdone // nothing to scale - shrl eax,1 // double pixel count - movl [loopcount],eax - -// -// build composite position -// - movl ebp,[_ds_xfrac] - shll ebp,10 - andl ebp,0ffff0000h - movl eax,[_ds_yfrac] - shrl eax,6 - andl eax,0ffffh - orl ebp,eax - - movl esi,[_ds_source] - -// -// calculate screen dest -// - movl edi,[_ds_y] - movl edi,[_ylookup+edi*4] - movl eax,[_ds_x1] - addl edi,[_columnofs+eax*4] - -// -// build composite step -// - movl ebx,[_ds_xstep] - shll ebx,10 - andl ebx,0ffff0000h - movl eax,[_ds_ystep] - shrl eax,6 - andl eax,0ffffh - orl ebx,eax - - movl eax,OFFSET hpatch1+2 // convice tasm to modify code... - movl [eax],ebx - movl eax,OFFSET hpatch2+2 // convice tasm to modify code... - movl [eax],ebx - -// eax aligned colormap -// ebx aligned colormap -// ecx,edx scratch -// esi virtual source -// edi moving destination pointer -// ebp frac - - shldl ecx,ebp,22 // begin calculating third pixel (y units) - shldl ecx,ebp,6 // begin calculating third pixel (x units) - addl ebp,ebx // advance frac pointer - andl ecx,4095 // finish calculation for third pixel - shldl edx,ebp,22 // begin calculating fourth pixel (y units) - shldl edx,ebp,6 // begin calculating fourth pixel (x units) - addl ebp,ebx // advance frac pointer - andl edx,4095 // finish calculation for fourth pixel - movl eax,[_ds_colormap] - movl ebx,eax - movb al,[esi+ecx] // get first pixel - movb bl,[esi+edx] // get second pixel - movb al,[eax] // color translate first pixel - movb bl,[ebx] // color translate second pixel - - testl [pixelcount],0fffffffeh - jnz hdoubleloop // at least two pixels to map - jmp hchecklast - - - .align 16 -hdoubleloop: - shldl ecx,ebp,22 // begin calculating third pixel (y units) - shldl ecx,ebp,6 // begin calculating third pixel (x units) -hpatch1: - addl ebp,12345678h // advance frac pointer - movb [edi],al // write first pixel - andl ecx,4095 // finish calculation for third pixel - shldl edx,ebp,22 // begin calculating fourth pixel (y units) - shldl edx,ebp,6 // begin calculating fourth pixel (x units) -hpatch2: - addl ebp,12345678h // advance frac pointer - movb [edi+1],bl // write second pixel - andl edx,4095 // finish calculation for fourth pixel - movb al,[esi+ecx] // get third pixel - addl edi,2 // advance to third pixel destination - movb bl,[esi+edx] // get fourth pixel - decl [loopcount] // done with loop? - movb al,[eax] // color translate third pixel - movb bl,[ebx] // color translate fourth pixel - jnz hdoubleloop - -// check for final pixel -hchecklast: - testl [pixelcount],1 - jz hdone - movb [edi],al // write final pixel - -hdone: - popad - ret - - - - -//==================================================== -// fpfunc.S as of January 10th, 1997 (parts) - -#ifdef i386 - -.text - .align 4 -.globl _FixedMul -_FixedMul: - pushl %ebp - movl %esp,%ebp - movl 8(%ebp),%eax - imull 12(%ebp) - shrdl $16,%edx,%eax - popl %ebp - ret - - - .align 4 -.globl _FixedDiv2 -_FixedDiv2: - pushl %ebp - movl %esp,%ebp - movl 8(%ebp),%eax - cdq - shldl $16,%eax,%edx - sall $16,%eax - idivl 12(%ebp) - popl %ebp - ret - -#endif - |