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//
// d_scana.s
// x86 assembly-language turbulent texture mapping code
//
#include "qasm.h"
#include "d_ifacea.h"
#if USE_ASM
.data
.text
//----------------------------------------------------------------------
// turbulent texture mapping code
//----------------------------------------------------------------------
.align 4
.globl C(D_DrawTurbulent8Span)
C(D_DrawTurbulent8Span):
pushl %ebp // preserve caller's stack frame pointer
pushl %esi // preserve register variables
pushl %edi
pushl %ebx
movl C(r_turb_s),%esi
movl C(r_turb_t),%ecx
movl C(r_turb_pdest),%edi
movl C(r_turb_spancount),%ebx
Llp:
movl %ecx,%eax
movl %esi,%edx
sarl $16,%eax
movl C(r_turb_turb),%ebp
sarl $16,%edx
andl $(CYCLE-1),%eax
andl $(CYCLE-1),%edx
movl (%ebp,%eax,4),%eax
movl (%ebp,%edx,4),%edx
addl %esi,%eax
sarl $16,%eax
addl %ecx,%edx
sarl $16,%edx
andl $(TURB_TEX_SIZE-1),%eax
andl $(TURB_TEX_SIZE-1),%edx
shll $6,%edx
movl C(r_turb_pbase),%ebp
addl %eax,%edx
incl %edi
addl C(r_turb_sstep),%esi
addl C(r_turb_tstep),%ecx
movb (%ebp,%edx,1),%dl
decl %ebx
movb %dl,-1(%edi)
jnz Llp
movl %edi,C(r_turb_pdest)
popl %ebx // restore register variables
popl %edi
popl %esi
popl %ebp // restore caller's stack frame pointer
ret
#endif // USE_ASM
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