ref: 245306e314fe636490b9ad7557a5ea234b589ef2
dir: /QW/client/r_drawa.s/
/*
Copyright (C) 1996-1997 Id Software, Inc.
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
//
// r_drawa.s
// x86 assembly-language edge clipping and emission code
//
#include "asm_i386.h"
#include "quakeasm.h"
#include "asm_draw.h"
#include "d_ifacea.h"
#if id386
// !!! if these are changed, they must be changed in r_draw.c too !!!
#define FULLY_CLIPPED_CACHED 0x80000000
#define FRAMECOUNT_MASK 0x7FFFFFFF
.data
Ld0: .single 0.0
Ld1: .single 0.0
Lstack: .long 0
Lfp_near_clip: .single NEAR_CLIP
Lceilv0: .long 0
Lv: .long 0
Lu0: .long 0
Lv0: .long 0
Lzi0: .long 0
.text
//----------------------------------------------------------------------
// edge clipping code
//----------------------------------------------------------------------
#define pv0 4+12
#define pv1 8+12
#define clip 12+12
.align 4
.globl C(R_ClipEdge)
C(R_ClipEdge):
pushl %esi // preserve register variables
pushl %edi
pushl %ebx
movl %esp,Lstack // for clearing the stack later
// float d0, d1, f;
// mvertex_t clipvert;
movl clip(%esp),%ebx
movl pv0(%esp),%esi
movl pv1(%esp),%edx
// if (clip)
// {
testl %ebx,%ebx
jz Lemit
// do
// {
Lcliploop:
// d0 = DotProduct (pv0->position, clip->normal) - clip->dist;
// d1 = DotProduct (pv1->position, clip->normal) - clip->dist;
flds mv_position+0(%esi)
fmuls cp_normal+0(%ebx)
flds mv_position+4(%esi)
fmuls cp_normal+4(%ebx)
flds mv_position+8(%esi)
fmuls cp_normal+8(%ebx)
fxch %st(1)
faddp %st(0),%st(2) // d0mul2 | d0add0
flds mv_position+0(%edx)
fmuls cp_normal+0(%ebx)
flds mv_position+4(%edx)
fmuls cp_normal+4(%ebx)
flds mv_position+8(%edx)
fmuls cp_normal+8(%ebx)
fxch %st(1)
faddp %st(0),%st(2) // d1mul2 | d1add0 | d0mul2 | d0add0
fxch %st(3) // d0add0 | d1add0 | d0mul2 | d1mul2
faddp %st(0),%st(2) // d1add0 | dot0 | d1mul2
faddp %st(0),%st(2) // dot0 | dot1
fsubs cp_dist(%ebx) // d0 | dot1
fxch %st(1) // dot1 | d0
fsubs cp_dist(%ebx) // d1 | d0
fxch %st(1)
fstps Ld0
fstps Ld1
// if (d0 >= 0)
// {
movl Ld0,%eax
movl Ld1,%ecx
orl %eax,%ecx
js Lp2
// both points are unclipped
Lcontinue:
//
// R_ClipEdge (&clipvert, pv1, clip->next);
// return;
// }
// } while ((clip = clip->next) != NULL);
movl cp_next(%ebx),%ebx
testl %ebx,%ebx
jnz Lcliploop
// }
//// add the edge
// R_EmitEdge (pv0, pv1);
Lemit:
//
// set integer rounding to ceil mode, set to single precision
//
// FIXME: do away with by manually extracting integers from floats?
// FIXME: set less often
fldcw ceil_cw
// edge_t *edge, *pcheck;
// int u_check;
// float u, u_step;
// vec3_t local, transformed;
// float *world;
// int v, v2, ceilv0;
// float scale, lzi0, u0, v0;
// int side;
// if (r_lastvertvalid)
// {
cmpl $0,C(r_lastvertvalid)
jz LCalcFirst
// u0 = r_u1;
// v0 = r_v1;
// lzi0 = r_lzi1;
// ceilv0 = r_ceilv1;
movl C(r_lzi1),%eax
movl C(r_u1),%ecx
movl %eax,Lzi0
movl %ecx,Lu0
movl C(r_v1),%ecx
movl C(r_ceilv1),%eax
movl %ecx,Lv0
movl %eax,Lceilv0
jmp LCalcSecond
// }
LCalcFirst:
// else
// {
// world = &pv0->position[0];
call LTransformAndProject // v0 | lzi0 | u0
fsts Lv0
fxch %st(2) // u0 | lzi0 | v0
fstps Lu0 // lzi0 | v0
fstps Lzi0 // v0
// ceilv0 = (int)(v0 - 2000) + 2000; // ceil(v0);
fistpl Lceilv0
// }
LCalcSecond:
// world = &pv1->position[0];
movl %edx,%esi
call LTransformAndProject // v1 | lzi1 | u1
flds Lu0 // u0 | v1 | lzi1 | u1
fxch %st(3) // u1 | v1 | lzi1 | u0
flds Lzi0 // lzi0 | u1 | v1 | lzi1 | u0
fxch %st(3) // lzi1 | u1 | v1 | lzi0 | u0
flds Lv0 // v0 | lzi1 | u1 | v1 | lzi0 | u0
fxch %st(3) // v1 | lzi1 | u1 | v0 | lzi0 | u0
// r_ceilv1 = (int)(r_v1 - 2000) + 2000; // ceil(r_v1);
fistl C(r_ceilv1)
fldcw single_cw // put back normal floating-point state
fsts C(r_v1)
fxch %st(4) // lzi0 | lzi1 | u1 | v0 | v1 | u0
// if (r_lzi1 > lzi0)
// lzi0 = r_lzi1;
fcom %st(1)
fnstsw %ax
testb $1,%ah
jz LP0
fstp %st(0)
fld %st(0)
LP0:
fxch %st(1) // lzi1 | lzi0 | u1 | v0 | v1 | u0
fstps C(r_lzi1) // lzi0 | u1 | v0 | v1 | u0
fxch %st(1)
fsts C(r_u1)
fxch %st(1)
// if (lzi0 > r_nearzi) // for mipmap finding
// r_nearzi = lzi0;
fcoms C(r_nearzi)
fnstsw %ax
testb $0x45,%ah
jnz LP1
fsts C(r_nearzi)
LP1:
// // for right edges, all we want is the effect on 1/z
// if (r_nearzionly)
// return;
movl C(r_nearzionly),%eax
testl %eax,%eax
jz LP2
LPop5AndDone:
movl C(cacheoffset),%eax
movl C(r_framecount),%edx
cmpl $0x7FFFFFFF,%eax
jz LDoPop
andl $(FRAMECOUNT_MASK),%edx
orl $(FULLY_CLIPPED_CACHED),%edx
movl %edx,C(cacheoffset)
LDoPop:
fstp %st(0) // u1 | v0 | v1 | u0
fstp %st(0) // v0 | v1 | u0
fstp %st(0) // v1 | u0
fstp %st(0) // u0
fstp %st(0)
jmp Ldone
LP2:
// // create the edge
// if (ceilv0 == r_ceilv1)
// return; // horizontal edge
movl Lceilv0,%ebx
movl C(edge_p),%edi
movl C(r_ceilv1),%ecx
movl %edi,%edx
movl C(r_pedge),%esi
addl $(et_size),%edx
cmpl %ecx,%ebx
jz LPop5AndDone
movl C(r_pedge),%eax
movl %eax,et_owner(%edi)
// side = ceilv0 > r_ceilv1;
//
// edge->nearzi = lzi0;
fstps et_nearzi(%edi) // u1 | v0 | v1 | u0
// if (side == 1)
// {
jc LSide0
LSide1:
// // leading edge (go from p2 to p1)
// u_step = ((u0 - r_u1) / (v0 - r_v1));
fsubrp %st(0),%st(3) // v0 | v1 | u0-u1
fsub %st(1),%st(0) // v0-v1 | v1 | u0-u1
fdivrp %st(0),%st(2) // v1 | ustep
// r_emitted = 1;
movl $1,C(r_emitted)
// edge = edge_p++;
movl %edx,C(edge_p)
// pretouch next edge
movl (%edx),%eax
// v2 = ceilv0 - 1;
// v = r_ceilv1;
movl %ecx,%eax
leal -1(%ebx),%ecx
movl %eax,%ebx
// edge->surfs[0] = 0;
// edge->surfs[1] = surface_p - surfaces;
movl C(surface_p),%eax
movl C(surfaces),%esi
subl %edx,%edx
subl %esi,%eax
shrl $(SURF_T_SHIFT),%eax
movl %edx,et_surfs(%edi)
movl %eax,et_surfs+2(%edi)
subl %esi,%esi
// u = r_u1 + ((float)v - r_v1) * u_step;
movl %ebx,Lv
fildl Lv // v | v1 | ustep
fsubp %st(0),%st(1) // v-v1 | ustep
fmul %st(1),%st(0) // (v-v1)*ustep | ustep
fadds C(r_u1) // u | ustep
jmp LSideDone
// }
LSide0:
// else
// {
// // trailing edge (go from p1 to p2)
// u_step = ((r_u1 - u0) / (r_v1 - v0));
fsub %st(3),%st(0) // u1-u0 | v0 | v1 | u0
fxch %st(2) // v1 | v0 | u1-u0 | u0
fsub %st(1),%st(0) // v1-v0 | v0 | u1-u0 | u0
fdivrp %st(0),%st(2) // v0 | ustep | u0
// r_emitted = 1;
movl $1,C(r_emitted)
// edge = edge_p++;
movl %edx,C(edge_p)
// pretouch next edge
movl (%edx),%eax
// v = ceilv0;
// v2 = r_ceilv1 - 1;
decl %ecx
// edge->surfs[0] = surface_p - surfaces;
// edge->surfs[1] = 0;
movl C(surface_p),%eax
movl C(surfaces),%esi
subl %edx,%edx
subl %esi,%eax
shrl $(SURF_T_SHIFT),%eax
movl %edx,et_surfs+2(%edi)
movl %eax,et_surfs(%edi)
movl $1,%esi
// u = u0 + ((float)v - v0) * u_step;
movl %ebx,Lv
fildl Lv // v | v0 | ustep | u0
fsubp %st(0),%st(1) // v-v0 | ustep | u0
fmul %st(1),%st(0) // (v-v0)*ustep | ustep | u0
faddp %st(0),%st(2) // ustep | u
fxch %st(1) // u | ustep
// }
LSideDone:
// edge->u_step = u_step*0x100000;
// edge->u = u*0x100000 + 0xFFFFF;
fmuls fp_1m // u*0x100000 | ustep
fxch %st(1) // ustep | u*0x100000
fmuls fp_1m // ustep*0x100000 | u*0x100000
fxch %st(1) // u*0x100000 | ustep*0x100000
fadds fp_1m_minus_1 // u*0x100000 + 0xFFFFF | ustep*0x100000
fxch %st(1) // ustep*0x100000 | u*0x100000 + 0xFFFFF
fistpl et_u_step(%edi) // u*0x100000 + 0xFFFFF
fistpl et_u(%edi)
// // we need to do this to avoid stepping off the edges if a very nearly
// // horizontal edge is less than epsilon above a scan, and numeric error
// // causes it to incorrectly extend to the scan, and the extension of the
// // line goes off the edge of the screen
// // FIXME: is this actually needed?
// if (edge->u < r_refdef.vrect_x_adj_shift20)
// edge->u = r_refdef.vrect_x_adj_shift20;
// if (edge->u > r_refdef.vrectright_adj_shift20)
// edge->u = r_refdef.vrectright_adj_shift20;
movl et_u(%edi),%eax
movl C(r_refdef)+rd_vrect_x_adj_shift20,%edx
cmpl %edx,%eax
jl LP4
movl C(r_refdef)+rd_vrectright_adj_shift20,%edx
cmpl %edx,%eax
jng LP5
LP4:
movl %edx,et_u(%edi)
movl %edx,%eax
LP5:
// // sort the edge in normally
// u_check = edge->u;
//
// if (edge->surfs[0])
// u_check++; // sort trailers after leaders
addl %esi,%eax
// if (!newedges[v] || newedges[v]->u >= u_check)
// {
movl C(newedges)(,%ebx,4),%esi
testl %esi,%esi
jz LDoFirst
cmpl %eax,et_u(%esi)
jl LNotFirst
LDoFirst:
// edge->next = newedges[v];
// newedges[v] = edge;
movl %esi,et_next(%edi)
movl %edi,C(newedges)(,%ebx,4)
jmp LSetRemove
// }
LNotFirst:
// else
// {
// pcheck = newedges[v];
//
// while (pcheck->next && pcheck->next->u < u_check)
// pcheck = pcheck->next;
LFindInsertLoop:
movl %esi,%edx
movl et_next(%esi),%esi
testl %esi,%esi
jz LInsertFound
cmpl %eax,et_u(%esi)
jl LFindInsertLoop
LInsertFound:
// edge->next = pcheck->next;
// pcheck->next = edge;
movl %esi,et_next(%edi)
movl %edi,et_next(%edx)
// }
LSetRemove:
// edge->nextremove = removeedges[v2];
// removeedges[v2] = edge;
movl C(removeedges)(,%ecx,4),%eax
movl %edi,C(removeedges)(,%ecx,4)
movl %eax,et_nextremove(%edi)
Ldone:
movl Lstack,%esp // clear temporary variables from stack
popl %ebx // restore register variables
popl %edi
popl %esi
ret
// at least one point is clipped
Lp2:
testl %eax,%eax
jns Lp1
// else
// {
// // point 0 is clipped
// if (d1 < 0)
// {
movl Ld1,%eax
testl %eax,%eax
jns Lp3
// // both points are clipped
// // we do cache fully clipped edges
// if (!leftclipped)
movl C(r_leftclipped),%eax
movl C(r_pedge),%ecx
testl %eax,%eax
jnz Ldone
// r_pedge->framecount = r_framecount;
movl C(r_framecount),%eax
andl $(FRAMECOUNT_MASK),%eax
orl $(FULLY_CLIPPED_CACHED),%eax
movl %eax,C(cacheoffset)
// return;
jmp Ldone
// }
Lp1:
// // point 0 is unclipped
// if (d1 >= 0)
// {
// // both points are unclipped
// continue;
// // only point 1 is clipped
// f = d0 / (d0 - d1);
flds Ld0
flds Ld1
fsubr %st(1),%st(0)
// // we don't cache partially clipped edges
movl $0x7FFFFFFF,C(cacheoffset)
fdivrp %st(0),%st(1)
subl $(mv_size),%esp // allocate space for clipvert
// clipvert.position[0] = pv0->position[0] +
// f * (pv1->position[0] - pv0->position[0]);
// clipvert.position[1] = pv0->position[1] +
// f * (pv1->position[1] - pv0->position[1]);
// clipvert.position[2] = pv0->position[2] +
// f * (pv1->position[2] - pv0->position[2]);
flds mv_position+8(%edx)
fsubs mv_position+8(%esi)
flds mv_position+4(%edx)
fsubs mv_position+4(%esi)
flds mv_position+0(%edx)
fsubs mv_position+0(%esi) // 0 | 1 | 2
// replace pv1 with the clip point
movl %esp,%edx
movl cp_leftedge(%ebx),%eax
testb %al,%al
fmul %st(3),%st(0)
fxch %st(1) // 1 | 0 | 2
fmul %st(3),%st(0)
fxch %st(2) // 2 | 0 | 1
fmulp %st(0),%st(3) // 0 | 1 | 2
fadds mv_position+0(%esi)
fxch %st(1) // 1 | 0 | 2
fadds mv_position+4(%esi)
fxch %st(2) // 2 | 0 | 1
fadds mv_position+8(%esi)
fxch %st(1) // 0 | 2 | 1
fstps mv_position+0(%esp) // 2 | 1
fstps mv_position+8(%esp) // 1
fstps mv_position+4(%esp)
// if (clip->leftedge)
// {
jz Ltestright
// r_leftclipped = true;
// r_leftexit = clipvert;
movl $1,C(r_leftclipped)
movl mv_position+0(%esp),%eax
movl %eax,C(r_leftexit)+mv_position+0
movl mv_position+4(%esp),%eax
movl %eax,C(r_leftexit)+mv_position+4
movl mv_position+8(%esp),%eax
movl %eax,C(r_leftexit)+mv_position+8
jmp Lcontinue
// }
Ltestright:
// else if (clip->rightedge)
// {
testb %ah,%ah
jz Lcontinue
// r_rightclipped = true;
// r_rightexit = clipvert;
movl $1,C(r_rightclipped)
movl mv_position+0(%esp),%eax
movl %eax,C(r_rightexit)+mv_position+0
movl mv_position+4(%esp),%eax
movl %eax,C(r_rightexit)+mv_position+4
movl mv_position+8(%esp),%eax
movl %eax,C(r_rightexit)+mv_position+8
// }
//
// R_ClipEdge (pv0, &clipvert, clip->next);
// return;
// }
jmp Lcontinue
// }
Lp3:
// // only point 0 is clipped
// r_lastvertvalid = false;
movl $0,C(r_lastvertvalid)
// f = d0 / (d0 - d1);
flds Ld0
flds Ld1
fsubr %st(1),%st(0)
// // we don't cache partially clipped edges
movl $0x7FFFFFFF,C(cacheoffset)
fdivrp %st(0),%st(1)
subl $(mv_size),%esp // allocate space for clipvert
// clipvert.position[0] = pv0->position[0] +
// f * (pv1->position[0] - pv0->position[0]);
// clipvert.position[1] = pv0->position[1] +
// f * (pv1->position[1] - pv0->position[1]);
// clipvert.position[2] = pv0->position[2] +
// f * (pv1->position[2] - pv0->position[2]);
flds mv_position+8(%edx)
fsubs mv_position+8(%esi)
flds mv_position+4(%edx)
fsubs mv_position+4(%esi)
flds mv_position+0(%edx)
fsubs mv_position+0(%esi) // 0 | 1 | 2
movl cp_leftedge(%ebx),%eax
testb %al,%al
fmul %st(3),%st(0)
fxch %st(1) // 1 | 0 | 2
fmul %st(3),%st(0)
fxch %st(2) // 2 | 0 | 1
fmulp %st(0),%st(3) // 0 | 1 | 2
fadds mv_position+0(%esi)
fxch %st(1) // 1 | 0 | 2
fadds mv_position+4(%esi)
fxch %st(2) // 2 | 0 | 1
fadds mv_position+8(%esi)
fxch %st(1) // 0 | 2 | 1
fstps mv_position+0(%esp) // 2 | 1
fstps mv_position+8(%esp) // 1
fstps mv_position+4(%esp)
// replace pv0 with the clip point
movl %esp,%esi
// if (clip->leftedge)
// {
jz Ltestright2
// r_leftclipped = true;
// r_leftenter = clipvert;
movl $1,C(r_leftclipped)
movl mv_position+0(%esp),%eax
movl %eax,C(r_leftenter)+mv_position+0
movl mv_position+4(%esp),%eax
movl %eax,C(r_leftenter)+mv_position+4
movl mv_position+8(%esp),%eax
movl %eax,C(r_leftenter)+mv_position+8
jmp Lcontinue
// }
Ltestright2:
// else if (clip->rightedge)
// {
testb %ah,%ah
jz Lcontinue
// r_rightclipped = true;
// r_rightenter = clipvert;
movl $1,C(r_rightclipped)
movl mv_position+0(%esp),%eax
movl %eax,C(r_rightenter)+mv_position+0
movl mv_position+4(%esp),%eax
movl %eax,C(r_rightenter)+mv_position+4
movl mv_position+8(%esp),%eax
movl %eax,C(r_rightenter)+mv_position+8
// }
jmp Lcontinue
// %esi = vec3_t point to transform and project
// %edx preserved
LTransformAndProject:
// // transform and project
// VectorSubtract (world, modelorg, local);
flds mv_position+0(%esi)
fsubs C(modelorg)+0
flds mv_position+4(%esi)
fsubs C(modelorg)+4
flds mv_position+8(%esi)
fsubs C(modelorg)+8
fxch %st(2) // local[0] | local[1] | local[2]
// TransformVector (local, transformed);
//
// if (transformed[2] < NEAR_CLIP)
// transformed[2] = NEAR_CLIP;
//
// lzi0 = 1.0 / transformed[2];
fld %st(0) // local[0] | local[0] | local[1] | local[2]
fmuls C(vpn)+0 // zm0 | local[0] | local[1] | local[2]
fld %st(1) // local[0] | zm0 | local[0] | local[1] |
// local[2]
fmuls C(vright)+0 // xm0 | zm0 | local[0] | local[1] | local[2]
fxch %st(2) // local[0] | zm0 | xm0 | local[1] | local[2]
fmuls C(vup)+0 // ym0 | zm0 | xm0 | local[1] | local[2]
fld %st(3) // local[1] | ym0 | zm0 | xm0 | local[1] |
// local[2]
fmuls C(vpn)+4 // zm1 | ym0 | zm0 | xm0 | local[1] |
// local[2]
fld %st(4) // local[1] | zm1 | ym0 | zm0 | xm0 |
// local[1] | local[2]
fmuls C(vright)+4 // xm1 | zm1 | ym0 | zm0 | xm0 |
// local[1] | local[2]
fxch %st(5) // local[1] | zm1 | ym0 | zm0 | xm0 |
// xm1 | local[2]
fmuls C(vup)+4 // ym1 | zm1 | ym0 | zm0 | xm0 |
// xm1 | local[2]
fxch %st(1) // zm1 | ym1 | ym0 | zm0 | xm0 |
// xm1 | local[2]
faddp %st(0),%st(3) // ym1 | ym0 | zm2 | xm0 | xm1 | local[2]
fxch %st(3) // xm0 | ym0 | zm2 | ym1 | xm1 | local[2]
faddp %st(0),%st(4) // ym0 | zm2 | ym1 | xm2 | local[2]
faddp %st(0),%st(2) // zm2 | ym2 | xm2 | local[2]
fld %st(3) // local[2] | zm2 | ym2 | xm2 | local[2]
fmuls C(vpn)+8 // zm3 | zm2 | ym2 | xm2 | local[2]
fld %st(4) // local[2] | zm3 | zm2 | ym2 | xm2 | local[2]
fmuls C(vright)+8 // xm3 | zm3 | zm2 | ym2 | xm2 | local[2]
fxch %st(5) // local[2] | zm3 | zm2 | ym2 | xm2 | xm3
fmuls C(vup)+8 // ym3 | zm3 | zm2 | ym2 | xm2 | xm3
fxch %st(1) // zm3 | ym3 | zm2 | ym2 | xm2 | xm3
faddp %st(0),%st(2) // ym3 | zm4 | ym2 | xm2 | xm3
fxch %st(4) // xm3 | zm4 | ym2 | xm2 | ym3
faddp %st(0),%st(3) // zm4 | ym2 | xm4 | ym3
fxch %st(1) // ym2 | zm4 | xm4 | ym3
faddp %st(0),%st(3) // zm4 | xm4 | ym4
fcoms Lfp_near_clip
fnstsw %ax
testb $1,%ah
jz LNoClip
fstp %st(0)
flds Lfp_near_clip
LNoClip:
fdivrs float_1 // lzi0 | x | y
fxch %st(1) // x | lzi0 | y
// // FIXME: build x/yscale into transform?
// scale = xscale * lzi0;
// u0 = (xcenter + scale*transformed[0]);
flds C(xscale) // xscale | x | lzi0 | y
fmul %st(2),%st(0) // scale | x | lzi0 | y
fmulp %st(0),%st(1) // scale*x | lzi0 | y
fadds C(xcenter) // u0 | lzi0 | y
// if (u0 < r_refdef.fvrectx_adj)
// u0 = r_refdef.fvrectx_adj;
// if (u0 > r_refdef.fvrectright_adj)
// u0 = r_refdef.fvrectright_adj;
// FIXME: use integer compares of floats?
fcoms C(r_refdef)+rd_fvrectx_adj
fnstsw %ax
testb $1,%ah
jz LClampP0
fstp %st(0)
flds C(r_refdef)+rd_fvrectx_adj
LClampP0:
fcoms C(r_refdef)+rd_fvrectright_adj
fnstsw %ax
testb $0x45,%ah
jnz LClampP1
fstp %st(0)
flds C(r_refdef)+rd_fvrectright_adj
LClampP1:
fld %st(1) // lzi0 | u0 | lzi0 | y
// scale = yscale * lzi0;
// v0 = (ycenter - scale*transformed[1]);
fmuls C(yscale) // scale | u0 | lzi0 | y
fmulp %st(0),%st(3) // u0 | lzi0 | scale*y
fxch %st(2) // scale*y | lzi0 | u0
fsubrs C(ycenter) // v0 | lzi0 | u0
// if (v0 < r_refdef.fvrecty_adj)
// v0 = r_refdef.fvrecty_adj;
// if (v0 > r_refdef.fvrectbottom_adj)
// v0 = r_refdef.fvrectbottom_adj;
// FIXME: use integer compares of floats?
fcoms C(r_refdef)+rd_fvrecty_adj
fnstsw %ax
testb $1,%ah
jz LClampP2
fstp %st(0)
flds C(r_refdef)+rd_fvrecty_adj
LClampP2:
fcoms C(r_refdef)+rd_fvrectbottom_adj
fnstsw %ax
testb $0x45,%ah
jnz LClampP3
fstp %st(0)
flds C(r_refdef)+rd_fvrectbottom_adj
LClampP3:
ret
#endif // id386