jedi-outcast/CODE-mp/unix/snapvector.nasm

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2013-04-04 18:24:26 +00:00
;
; Sys_SnapVector NASM code (Andrew Henderson)
; See win32/win_shared.c for the Win32 equivalent
; This code is provided to ensure that the
; rounding behavior (and, if necessary, the
; precision) of DLL and QVM code are identical
; e.g. for network-visible operations.
; See ftol.nasm for operations on a single float,
; as used in compiled VM and DLL code that does
; not use this system trap.
;
segment .data
fpucw dd 0
cw037F dd 0x037F ; Rounding to nearest (even).
segment .text
; void Sys_SnapVector( float *v )
global Sys_SnapVector
Sys_SnapVector:
push eax
push ebp
mov ebp, esp
fnstcw [fpucw]
mov eax, dword [ebp + 12]
fldcw [cw037F]
fld dword [eax]
fistp dword [eax]
fild dword [eax]
fstp dword [eax]
fld dword [eax + 4]
fistp dword [eax + 4]
fild dword [eax + 4]
fstp dword [eax + 4]
fld dword [eax + 8]
fistp dword [eax + 8]
fild dword [eax + 8]
fstp dword [eax + 8]
fldcw [fpucw]
pop ebp
pop eax
ret
; void Sys_SnapVectorCW( float *v, unsigned short int cw )
global Sys_SnapVectorCW
Sys_SnapVector_cw:
push eax
push ebp
mov ebp, esp
fnstcw [fpucw]
mov eax, dword [ebp + 12]
fldcw [ebp + 16]
fld dword [eax]
fistp dword [eax]
fild dword [eax]
fstp dword [eax]
fld dword [eax + 4]
fistp dword [eax + 4]
fild dword [eax + 4]
fstp dword [eax + 4]
fld dword [eax + 8]
fistp dword [eax + 8]
fild dword [eax + 8]
fstp dword [eax + 8]
fldcw [fpucw]
pop ebp
pop eax
ret