ref: 06eb848b99587ef882c121a5a65d2082e3b88aeb
dir: qk1/d_draw.s
// // d_draw.s // x86 assembly-language horizontal 8-bpp span-drawing code. // #include "asm_i386.h" #include "quakeasm.h" #include "asm_draw.h" #include "d_ifacea.h" #ifdef id386 //---------------------------------------------------------------------- // 8-bpp horizontal span drawing code for polygons, with no transparency. // // Assumes there is at least one span in pspans, and that every span // contains at least one pixel //---------------------------------------------------------------------- .text // out-of-line, rarely-needed clamping code LClampHigh0: movl C(bbextents),%esi jmp LClampReentry0 LClampHighOrLow0: jg LClampHigh0 xorl %esi,%esi jmp LClampReentry0 LClampHigh1: movl C(bbextentt),%edx jmp LClampReentry1 LClampHighOrLow1: jg LClampHigh1 xorl %edx,%edx jmp LClampReentry1 LClampLow2: movl $2048,%ebp jmp LClampReentry2 LClampHigh2: movl C(bbextents),%ebp jmp LClampReentry2 LClampLow3: movl $2048,%ecx jmp LClampReentry3 LClampHigh3: movl C(bbextentt),%ecx jmp LClampReentry3 LClampLow4: movl $2048,%eax jmp LClampReentry4 LClampHigh4: movl C(bbextents),%eax jmp LClampReentry4 LClampLow5: movl $2048,%ebx jmp LClampReentry5 LClampHigh5: movl C(bbextentt),%ebx jmp LClampReentry5 #define pspans 4+16 .align 4 .globl C(D_DrawSpans8) C(D_DrawSpans8): pushl %ebp // preserve caller's stack frame pushl %edi pushl %esi // preserve register variables pushl %ebx // // set up scaled-by-8 steps, for 8-long segments; also set up cacheblock // and span list pointers // // TODO: any overlap from rearranging? flds C(d_sdivzstepu) fmuls fp_8 movl C(cacheblock),%edx flds C(d_tdivzstepu) fmuls fp_8 movl pspans(%esp),%ebx // point to the first span descriptor flds C(d_zistepu) fmuls fp_8 movl %edx,pbase // pbase = cacheblock fstps zi8stepu fstps tdivz8stepu fstps sdivz8stepu LSpanLoop: // // set up the initial s/z, t/z, and 1/z on the FP stack, and generate the // initial s and t values // // FIXME: pipeline FILD? fildl espan_t_v(%ebx) fildl espan_t_u(%ebx) fld %st(1) // dv | du | dv fmuls C(d_sdivzstepv) // dv*d_sdivzstepv | du | dv fld %st(1) // du | dv*d_sdivzstepv | du | dv fmuls C(d_sdivzstepu) // du*d_sdivzstepu | dv*d_sdivzstepv | du | dv fld %st(2) // du | du*d_sdivzstepu | dv*d_sdivzstepv | du | dv fmuls C(d_tdivzstepu) // du*d_tdivzstepu | du*d_sdivzstepu | // dv*d_sdivzstepv | du | dv fxch %st(1) // du*d_sdivzstepu | du*d_tdivzstepu | // dv*d_sdivzstepv | du | dv faddp %st(0),%st(2) // du*d_tdivzstepu | // du*d_sdivzstepu + dv*d_sdivzstepv | du | dv fxch %st(1) // du*d_sdivzstepu + dv*d_sdivzstepv | // du*d_tdivzstepu | du | dv fld %st(3) // dv | du*d_sdivzstepu + dv*d_sdivzstepv | // du*d_tdivzstepu | du | dv fmuls C(d_tdivzstepv) // dv*d_tdivzstepv | // du*d_sdivzstepu + dv*d_sdivzstepv | // du*d_tdivzstepu | du | dv fxch %st(1) // du*d_sdivzstepu + dv*d_sdivzstepv | // dv*d_tdivzstepv | du*d_tdivzstepu | du | dv fadds C(d_sdivzorigin) // sdivz = d_sdivzorigin + dv*d_sdivzstepv + // du*d_sdivzstepu; stays in %st(2) at end fxch %st(4) // dv | dv*d_tdivzstepv | du*d_tdivzstepu | du | // s/z fmuls C(d_zistepv) // dv*d_zistepv | dv*d_tdivzstepv | // du*d_tdivzstepu | du | s/z fxch %st(1) // dv*d_tdivzstepv | dv*d_zistepv | // du*d_tdivzstepu | du | s/z faddp %st(0),%st(2) // dv*d_zistepv | // dv*d_tdivzstepv + du*d_tdivzstepu | du | s/z fxch %st(2) // du | dv*d_tdivzstepv + du*d_tdivzstepu | // dv*d_zistepv | s/z fmuls C(d_zistepu) // du*d_zistepu | // dv*d_tdivzstepv + du*d_tdivzstepu | // dv*d_zistepv | s/z fxch %st(1) // dv*d_tdivzstepv + du*d_tdivzstepu | // du*d_zistepu | dv*d_zistepv | s/z fadds C(d_tdivzorigin) // tdivz = d_tdivzorigin + dv*d_tdivzstepv + // du*d_tdivzstepu; stays in %st(1) at end fxch %st(2) // dv*d_zistepv | du*d_zistepu | t/z | s/z faddp %st(0),%st(1) // dv*d_zistepv + du*d_zistepu | t/z | s/z flds fp_64k // fp_64k | dv*d_zistepv + du*d_zistepu | t/z | s/z fxch %st(1) // dv*d_zistepv + du*d_zistepu | fp_64k | t/z | s/z fadds C(d_ziorigin) // zi = d_ziorigin + dv*d_zistepv + // du*d_zistepu; stays in %st(0) at end // 1/z | fp_64k | t/z | s/z // // calculate and clamp s & t // fdivr %st(0),%st(1) // 1/z | z*64k | t/z | s/z // // point %edi to the first pixel in the span // movl C(d_viewbuffer),%ecx movl espan_t_v(%ebx),%eax movl %ebx,pspantemp // preserve spans pointer movl C(tadjust),%edx movl C(sadjust),%esi movl C(d_scantable)(,%eax,4),%edi // v * screenwidth addl %ecx,%edi movl espan_t_u(%ebx),%ecx addl %ecx,%edi // pdest = &pdestspan[scans->u]; movl espan_t_count(%ebx),%ecx // // now start the FDIV for the end of the span // cmpl $8,%ecx ja LSetupNotLast1 decl %ecx jz LCleanup1 // if only one pixel, no need to start an FDIV movl %ecx,spancountminus1 // finish up the s and t calcs fxch %st(1) // z*64k | 1/z | t/z | s/z fld %st(0) // z*64k | z*64k | 1/z | t/z | s/z fmul %st(4),%st(0) // s | z*64k | 1/z | t/z | s/z fxch %st(1) // z*64k | s | 1/z | t/z | s/z fmul %st(3),%st(0) // t | s | 1/z | t/z | s/z fxch %st(1) // s | t | 1/z | t/z | s/z fistpl s // 1/z | t | t/z | s/z fistpl t // 1/z | t/z | s/z fildl spancountminus1 flds C(d_tdivzstepu) // C(d_tdivzstepu) | spancountminus1 flds C(d_zistepu) // C(d_zistepu) | C(d_tdivzstepu) | spancountminus1 fmul %st(2),%st(0) // C(d_zistepu)*scm1 | C(d_tdivzstepu) | scm1 fxch %st(1) // C(d_tdivzstepu) | C(d_zistepu)*scm1 | scm1 fmul %st(2),%st(0) // C(d_tdivzstepu)*scm1 | C(d_zistepu)*scm1 | scm1 fxch %st(2) // scm1 | C(d_zistepu)*scm1 | C(d_tdivzstepu)*scm1 fmuls C(d_sdivzstepu) // C(d_sdivzstepu)*scm1 | C(d_zistepu)*scm1 | // C(d_tdivzstepu)*scm1 fxch %st(1) // C(d_zistepu)*scm1 | C(d_sdivzstepu)*scm1 | // C(d_tdivzstepu)*scm1 faddp %st(0),%st(3) // C(d_sdivzstepu)*scm1 | C(d_tdivzstepu)*scm1 fxch %st(1) // C(d_tdivzstepu)*scm1 | C(d_sdivzstepu)*scm1 faddp %st(0),%st(3) // C(d_sdivzstepu)*scm1 faddp %st(0),%st(3) flds fp_64k fdiv %st(1),%st(0) // this is what we've gone to all this trouble to // overlap jmp LFDIVInFlight1 LCleanup1: // finish up the s and t calcs fxch %st(1) // z*64k | 1/z | t/z | s/z fld %st(0) // z*64k | z*64k | 1/z | t/z | s/z fmul %st(4),%st(0) // s | z*64k | 1/z | t/z | s/z fxch %st(1) // z*64k | s | 1/z | t/z | s/z fmul %st(3),%st(0) // t | s | 1/z | t/z | s/z fxch %st(1) // s | t | 1/z | t/z | s/z fistpl s // 1/z | t | t/z | s/z fistpl t // 1/z | t/z | s/z jmp LFDIVInFlight1 .align 4 LSetupNotLast1: // finish up the s and t calcs fxch %st(1) // z*64k | 1/z | t/z | s/z fld %st(0) // z*64k | z*64k | 1/z | t/z | s/z fmul %st(4),%st(0) // s | z*64k | 1/z | t/z | s/z fxch %st(1) // z*64k | s | 1/z | t/z | s/z fmul %st(3),%st(0) // t | s | 1/z | t/z | s/z fxch %st(1) // s | t | 1/z | t/z | s/z fistpl s // 1/z | t | t/z | s/z fistpl t // 1/z | t/z | s/z fadds zi8stepu fxch %st(2) fadds sdivz8stepu fxch %st(2) flds tdivz8stepu faddp %st(0),%st(2) flds fp_64k fdiv %st(1),%st(0) // z = 1/1/z // this is what we've gone to all this trouble to // overlap LFDIVInFlight1: addl s,%esi addl t,%edx movl C(bbextents),%ebx movl C(bbextentt),%ebp cmpl %ebx,%esi ja LClampHighOrLow0 LClampReentry0: movl %esi,s movl pbase,%ebx shll $16,%esi cmpl %ebp,%edx movl %esi,sfracf ja LClampHighOrLow1 LClampReentry1: movl %edx,t movl s,%esi // sfrac = scans->sfrac; shll $16,%edx movl t,%eax // tfrac = scans->tfrac; sarl $16,%esi movl %edx,tfracf // // calculate the texture starting address // sarl $16,%eax movl C(cachewidth),%edx imull %edx,%eax // (tfrac >> 16) * cachewidth addl %ebx,%esi addl %eax,%esi // psource = pbase + (sfrac >> 16) + // ((tfrac >> 16) * cachewidth); // // determine whether last span or not // cmpl $8,%ecx jna LLastSegment // // not the last segment; do full 8-wide segment // LNotLastSegment: // // advance s/z, t/z, and 1/z, and calculate s & t at end of span and steps to // get there // // pick up after the FDIV that was left in flight previously fld %st(0) // duplicate it fmul %st(4),%st(0) // s = s/z * z fxch %st(1) fmul %st(3),%st(0) // t = t/z * z fxch %st(1) fistpl snext fistpl tnext movl snext,%eax movl tnext,%edx movb (%esi),%bl // get first source texel subl $8,%ecx // count off this segments' pixels movl C(sadjust),%ebp movl %ecx,counttemp // remember count of remaining pixels movl C(tadjust),%ecx movb %bl,(%edi) // store first dest pixel addl %eax,%ebp addl %edx,%ecx movl C(bbextents),%eax movl C(bbextentt),%edx cmpl $2048,%ebp jl LClampLow2 cmpl %eax,%ebp ja LClampHigh2 LClampReentry2: cmpl $2048,%ecx jl LClampLow3 cmpl %edx,%ecx ja LClampHigh3 LClampReentry3: movl %ebp,snext movl %ecx,tnext subl s,%ebp subl t,%ecx // // set up advancetable // movl %ecx,%eax movl %ebp,%edx sarl $19,%eax // tstep >>= 16; jz LZero sarl $19,%edx // sstep >>= 16; movl C(cachewidth),%ebx imull %ebx,%eax jmp LSetUp1 LZero: sarl $19,%edx // sstep >>= 16; movl C(cachewidth),%ebx LSetUp1: addl %edx,%eax // add in sstep // (tstep >> 16) * cachewidth + (sstep >> 16); movl tfracf,%edx movl %eax,advancetable+4 // advance base in t addl %ebx,%eax // ((tstep >> 16) + 1) * cachewidth + // (sstep >> 16); shll $13,%ebp // left-justify sstep fractional part movl sfracf,%ebx shll $13,%ecx // left-justify tstep fractional part movl %eax,advancetable // advance extra in t movl %ecx,tstep addl %ecx,%edx // advance tfrac fractional part by tstep frac sbbl %ecx,%ecx // turn tstep carry into -1 (0 if none) addl %ebp,%ebx // advance sfrac fractional part by sstep frac adcl advancetable+4(,%ecx,4),%esi // point to next source texel addl tstep,%edx sbbl %ecx,%ecx movb (%esi),%al addl %ebp,%ebx movb %al,1(%edi) adcl advancetable+4(,%ecx,4),%esi addl tstep,%edx sbbl %ecx,%ecx addl %ebp,%ebx movb (%esi),%al adcl advancetable+4(,%ecx,4),%esi addl tstep,%edx sbbl %ecx,%ecx movb %al,2(%edi) addl %ebp,%ebx movb (%esi),%al adcl advancetable+4(,%ecx,4),%esi addl tstep,%edx sbbl %ecx,%ecx movb %al,3(%edi) addl %ebp,%ebx movb (%esi),%al adcl advancetable+4(,%ecx,4),%esi // // start FDIV for end of next segment in flight, so it can overlap // movl counttemp,%ecx cmpl $8,%ecx // more than one segment after this? ja LSetupNotLast2 // yes decl %ecx jz LFDIVInFlight2 // if only one pixel, no need to start an FDIV movl %ecx,spancountminus1 fildl spancountminus1 flds C(d_zistepu) // C(d_zistepu) | spancountminus1 fmul %st(1),%st(0) // C(d_zistepu)*scm1 | scm1 flds C(d_tdivzstepu) // C(d_tdivzstepu) | C(d_zistepu)*scm1 | scm1 fmul %st(2),%st(0) // C(d_tdivzstepu)*scm1 | C(d_zistepu)*scm1 | scm1 fxch %st(1) // C(d_zistepu)*scm1 | C(d_tdivzstepu)*scm1 | scm1 faddp %st(0),%st(3) // C(d_tdivzstepu)*scm1 | scm1 fxch %st(1) // scm1 | C(d_tdivzstepu)*scm1 fmuls C(d_sdivzstepu) // C(d_sdivzstepu)*scm1 | C(d_tdivzstepu)*scm1 fxch %st(1) // C(d_tdivzstepu)*scm1 | C(d_sdivzstepu)*scm1 faddp %st(0),%st(3) // C(d_sdivzstepu)*scm1 flds fp_64k // 64k | C(d_sdivzstepu)*scm1 fxch %st(1) // C(d_sdivzstepu)*scm1 | 64k faddp %st(0),%st(4) // 64k fdiv %st(1),%st(0) // this is what we've gone to all this trouble to // overlap jmp LFDIVInFlight2 .align 4 LSetupNotLast2: fadds zi8stepu fxch %st(2) fadds sdivz8stepu fxch %st(2) flds tdivz8stepu faddp %st(0),%st(2) flds fp_64k fdiv %st(1),%st(0) // z = 1/1/z // this is what we've gone to all this trouble to // overlap LFDIVInFlight2: movl %ecx,counttemp addl tstep,%edx sbbl %ecx,%ecx movb %al,4(%edi) addl %ebp,%ebx movb (%esi),%al adcl advancetable+4(,%ecx,4),%esi addl tstep,%edx sbbl %ecx,%ecx movb %al,5(%edi) addl %ebp,%ebx movb (%esi),%al adcl advancetable+4(,%ecx,4),%esi addl tstep,%edx sbbl %ecx,%ecx movb %al,6(%edi) addl %ebp,%ebx movb (%esi),%al adcl advancetable+4(,%ecx,4),%esi addl $8,%edi movl %edx,tfracf movl snext,%edx movl %ebx,sfracf movl tnext,%ebx movl %edx,s movl %ebx,t movl counttemp,%ecx // retrieve count // // determine whether last span or not // cmpl $8,%ecx // are there multiple segments remaining? movb %al,-1(%edi) ja LNotLastSegment // yes // // last segment of scan // LLastSegment: // // advance s/z, t/z, and 1/z, and calculate s & t at end of span and steps to // get there. The number of pixels left is variable, and we want to land on the // last pixel, not step one past it, so we can't run into arithmetic problems // testl %ecx,%ecx jz LNoSteps // just draw the last pixel and we're done // pick up after the FDIV that was left in flight previously fld %st(0) // duplicate it fmul %st(4),%st(0) // s = s/z * z fxch %st(1) fmul %st(3),%st(0) // t = t/z * z fxch %st(1) fistpl snext fistpl tnext movb (%esi),%al // load first texel in segment movl C(tadjust),%ebx movb %al,(%edi) // store first pixel in segment movl C(sadjust),%eax addl snext,%eax addl tnext,%ebx movl C(bbextents),%ebp movl C(bbextentt),%edx cmpl $2048,%eax jl LClampLow4 cmpl %ebp,%eax ja LClampHigh4 LClampReentry4: movl %eax,snext cmpl $2048,%ebx jl LClampLow5 cmpl %edx,%ebx ja LClampHigh5 LClampReentry5: cmpl $1,%ecx // don't bother je LOnlyOneStep // if two pixels in segment, there's only one step, // of the segment length subl s,%eax subl t,%ebx addl %eax,%eax // convert to 15.17 format so multiply by 1.31 addl %ebx,%ebx // reciprocal yields 16.48 imull reciprocal_table-8(,%ecx,4) // sstep = (snext - s) / (spancount-1) movl %edx,%ebp movl %ebx,%eax imull reciprocal_table-8(,%ecx,4) // tstep = (tnext - t) / (spancount-1) LSetEntryvec: // // set up advancetable // movl entryvec_table(,%ecx,4),%ebx movl %edx,%eax movl %ebx,jumptemp // entry point into code for RET later movl %ebp,%ecx sarl $16,%edx // tstep >>= 16; movl C(cachewidth),%ebx sarl $16,%ecx // sstep >>= 16; imull %ebx,%edx addl %ecx,%edx // add in sstep // (tstep >> 16) * cachewidth + (sstep >> 16); movl tfracf,%ecx movl %edx,advancetable+4 // advance base in t addl %ebx,%edx // ((tstep >> 16) + 1) * cachewidth + // (sstep >> 16); shll $16,%ebp // left-justify sstep fractional part movl sfracf,%ebx shll $16,%eax // left-justify tstep fractional part movl %edx,advancetable // advance extra in t movl %eax,tstep movl %ecx,%edx addl %eax,%edx sbbl %ecx,%ecx addl %ebp,%ebx adcl advancetable+4(,%ecx,4),%esi jmp *jumptemp // jump to the number-of-pixels handler //---------------------------------------- LNoSteps: movb (%esi),%al // load first texel in segment subl $7,%edi // adjust for hardwired offset jmp LEndSpan LOnlyOneStep: subl s,%eax subl t,%ebx movl %eax,%ebp movl %ebx,%edx jmp LSetEntryvec //---------------------------------------- .globl Entry2_8 Entry2_8: subl $6,%edi // adjust for hardwired offsets movb (%esi),%al jmp LLEntry2_8 //---------------------------------------- .globl Entry3_8 Entry3_8: subl $5,%edi // adjust for hardwired offsets addl %eax,%edx movb (%esi),%al sbbl %ecx,%ecx addl %ebp,%ebx adcl advancetable+4(,%ecx,4),%esi jmp LLEntry3_8 //---------------------------------------- .globl Entry4_8 Entry4_8: subl $4,%edi // adjust for hardwired offsets addl %eax,%edx movb (%esi),%al sbbl %ecx,%ecx addl %ebp,%ebx adcl advancetable+4(,%ecx,4),%esi addl tstep,%edx jmp LLEntry4_8 //---------------------------------------- .globl Entry5_8 Entry5_8: subl $3,%edi // adjust for hardwired offsets addl %eax,%edx movb (%esi),%al sbbl %ecx,%ecx addl %ebp,%ebx adcl advancetable+4(,%ecx,4),%esi addl tstep,%edx jmp LLEntry5_8 //---------------------------------------- .globl Entry6_8 Entry6_8: subl $2,%edi // adjust for hardwired offsets addl %eax,%edx movb (%esi),%al sbbl %ecx,%ecx addl %ebp,%ebx adcl advancetable+4(,%ecx,4),%esi addl tstep,%edx jmp LLEntry6_8 //---------------------------------------- .globl Entry7_8 Entry7_8: decl %edi // adjust for hardwired offsets addl %eax,%edx movb (%esi),%al sbbl %ecx,%ecx addl %ebp,%ebx adcl advancetable+4(,%ecx,4),%esi addl tstep,%edx jmp LLEntry7_8 //---------------------------------------- .globl Entry8_8 Entry8_8: addl %eax,%edx movb (%esi),%al sbbl %ecx,%ecx addl %ebp,%ebx adcl advancetable+4(,%ecx,4),%esi addl tstep,%edx sbbl %ecx,%ecx movb %al,1(%edi) addl %ebp,%ebx movb (%esi),%al adcl advancetable+4(,%ecx,4),%esi addl tstep,%edx LLEntry7_8: sbbl %ecx,%ecx movb %al,2(%edi) addl %ebp,%ebx movb (%esi),%al adcl advancetable+4(,%ecx,4),%esi addl tstep,%edx LLEntry6_8: sbbl %ecx,%ecx movb %al,3(%edi) addl %ebp,%ebx movb (%esi),%al adcl advancetable+4(,%ecx,4),%esi addl tstep,%edx LLEntry5_8: sbbl %ecx,%ecx movb %al,4(%edi) addl %ebp,%ebx movb (%esi),%al adcl advancetable+4(,%ecx,4),%esi addl tstep,%edx LLEntry4_8: sbbl %ecx,%ecx movb %al,5(%edi) addl %ebp,%ebx movb (%esi),%al adcl advancetable+4(,%ecx,4),%esi LLEntry3_8: movb %al,6(%edi) movb (%esi),%al LLEntry2_8: LEndSpan: // // clear s/z, t/z, 1/z from FP stack // fstp %st(0) fstp %st(0) fstp %st(0) movl pspantemp,%ebx // restore spans pointer movl espan_t_pnext(%ebx),%ebx // point to next span testl %ebx,%ebx // any more spans? movb %al,7(%edi) jnz LSpanLoop // more spans popl %ebx // restore register variables popl %esi popl %edi popl %ebp // restore the caller's stack frame ret //---------------------------------------------------------------------- // 8-bpp horizontal span z drawing codefor polygons, with no transparency. // // Assumes there is at least one span in pzspans, and that every span // contains at least one pixel //---------------------------------------------------------------------- .text // z-clamp on a non-negative gradient span LClamp: movl $0x40000000,%edx xorl %ebx,%ebx fstp %st(0) jmp LZDraw // z-clamp on a negative gradient span LClampNeg: movl $0x40000000,%edx xorl %ebx,%ebx fstp %st(0) jmp LZDrawNeg #define pzspans 4+16 .globl C(D_DrawZSpans) C(D_DrawZSpans): pushl %ebp // preserve caller's stack frame pushl %edi pushl %esi // preserve register variables pushl %ebx flds C(d_zistepu) movl C(d_zistepu),%eax movl pzspans(%esp),%esi testl %eax,%eax jz LFNegSpan fmuls Float2ToThe31nd fistpl izistep // note: we are relying on FP exceptions being turned // off here to avoid range problems movl izistep,%ebx // remains loaded for all spans LFSpanLoop: // set up the initial 1/z value fildl espan_t_v(%esi) fildl espan_t_u(%esi) movl espan_t_v(%esi),%ecx movl C(d_pzbuffer),%edi fmuls C(d_zistepu) fxch %st(1) fmuls C(d_zistepv) fxch %st(1) fadds C(d_ziorigin) imull C(d_zrowbytes),%ecx faddp %st(0),%st(1) // clamp if z is nearer than 2 (1/z > 0.5) fcoms float_point5 addl %ecx,%edi movl espan_t_u(%esi),%edx addl %edx,%edx // word count movl espan_t_count(%esi),%ecx addl %edx,%edi // pdest = &pdestspan[scans->u]; pushl %esi // preserve spans pointer fnstsw %ax testb $0x45,%ah jz LClamp fmuls Float2ToThe31nd fistpl izi // note: we are relying on FP exceptions being turned // off here to avoid problems when the span is closer // than 1/(2**31) movl izi,%edx // at this point: // %ebx = izistep // %ecx = count // %edx = izi // %edi = pdest LZDraw: // do a single pixel up front, if necessary to dword align the destination testl $2,%edi jz LFMiddle movl %edx,%eax addl %ebx,%edx shrl $16,%eax decl %ecx movw %ax,(%edi) addl $2,%edi // do middle a pair of aligned dwords at a time LFMiddle: pushl %ecx shrl $1,%ecx // count / 2 jz LFLast // no aligned dwords to do shrl $1,%ecx // (count / 2) / 2 jnc LFMiddleLoop // even number of aligned dwords to do movl %edx,%eax addl %ebx,%edx shrl $16,%eax movl %edx,%esi addl %ebx,%edx andl $0xFFFF0000,%esi orl %esi,%eax movl %eax,(%edi) addl $4,%edi andl %ecx,%ecx jz LFLast LFMiddleLoop: movl %edx,%eax addl %ebx,%edx shrl $16,%eax movl %edx,%esi addl %ebx,%edx andl $0xFFFF0000,%esi orl %esi,%eax movl %edx,%ebp movl %eax,(%edi) addl %ebx,%edx shrl $16,%ebp movl %edx,%esi addl %ebx,%edx andl $0xFFFF0000,%esi orl %esi,%ebp movl %ebp,4(%edi) // FIXME: eliminate register contention addl $8,%edi decl %ecx jnz LFMiddleLoop LFLast: popl %ecx // retrieve count popl %esi // retrieve span pointer // do the last, unaligned pixel, if there is one andl $1,%ecx // is there an odd pixel left to do? jz LFSpanDone // no shrl $16,%edx movw %dx,(%edi) // do the final pixel's z LFSpanDone: movl espan_t_pnext(%esi),%esi testl %esi,%esi jnz LFSpanLoop jmp LFDone LFNegSpan: fmuls FloatMinus2ToThe31nd fistpl izistep // note: we are relying on FP exceptions being turned // off here to avoid range problems movl izistep,%ebx // remains loaded for all spans LFNegSpanLoop: // set up the initial 1/z value fildl espan_t_v(%esi) fildl espan_t_u(%esi) movl espan_t_v(%esi),%ecx movl C(d_pzbuffer),%edi fmuls C(d_zistepu) fxch %st(1) fmuls C(d_zistepv) fxch %st(1) fadds C(d_ziorigin) imull C(d_zrowbytes),%ecx faddp %st(0),%st(1) // clamp if z is nearer than 2 (1/z > 0.5) fcoms float_point5 addl %ecx,%edi movl espan_t_u(%esi),%edx addl %edx,%edx // word count movl espan_t_count(%esi),%ecx addl %edx,%edi // pdest = &pdestspan[scans->u]; pushl %esi // preserve spans pointer fnstsw %ax testb $0x45,%ah jz LClampNeg fmuls Float2ToThe31nd fistpl izi // note: we are relying on FP exceptions being turned // off here to avoid problems when the span is closer // than 1/(2**31) movl izi,%edx // at this point: // %ebx = izistep // %ecx = count // %edx = izi // %edi = pdest LZDrawNeg: // do a single pixel up front, if necessary to dword align the destination testl $2,%edi jz LFNegMiddle movl %edx,%eax subl %ebx,%edx shrl $16,%eax decl %ecx movw %ax,(%edi) addl $2,%edi // do middle a pair of aligned dwords at a time LFNegMiddle: pushl %ecx shrl $1,%ecx // count / 2 jz LFNegLast // no aligned dwords to do shrl $1,%ecx // (count / 2) / 2 jnc LFNegMiddleLoop // even number of aligned dwords to do movl %edx,%eax subl %ebx,%edx shrl $16,%eax movl %edx,%esi subl %ebx,%edx andl $0xFFFF0000,%esi orl %esi,%eax movl %eax,(%edi) addl $4,%edi andl %ecx,%ecx jz LFNegLast LFNegMiddleLoop: movl %edx,%eax subl %ebx,%edx shrl $16,%eax movl %edx,%esi subl %ebx,%edx andl $0xFFFF0000,%esi orl %esi,%eax movl %edx,%ebp movl %eax,(%edi) subl %ebx,%edx shrl $16,%ebp movl %edx,%esi subl %ebx,%edx andl $0xFFFF0000,%esi orl %esi,%ebp movl %ebp,4(%edi) // FIXME: eliminate register contention addl $8,%edi decl %ecx jnz LFNegMiddleLoop LFNegLast: popl %ecx // retrieve count popl %esi // retrieve span pointer // do the last, unaligned pixel, if there is one andl $1,%ecx // is there an odd pixel left to do? jz LFNegSpanDone // no shrl $16,%edx movw %dx,(%edi) // do the final pixel's z LFNegSpanDone: movl espan_t_pnext(%esi),%esi testl %esi,%esi jnz LFNegSpanLoop LFDone: popl %ebx // restore register variables popl %esi popl %edi popl %ebp // restore the caller's stack frame ret #endif // id386