mirror of
https://github.com/ZDoom/gzdoom.git
synced 2024-11-08 22:11:09 +00:00
283 lines
6.8 KiB
NASM
283 lines
6.8 KiB
NASM
|
|
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
|
|
|