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# Pure Data Packet mmx routine.
# Copyright (c) by Tom Schouten <tom@zwizwa.be>
#
# 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., 675 Mass Ave, Cambridge, MA 02139, USA.
#
.globl pixel_gain
.type pixel_gain,@function
# mmx rgba pixel gain
# void asmtest(char *pixelarray, int32 nbpixels, int *rgba_gain)
# gains are 7.9 fixed point for rgba
pixel_gain:
pushl %ebp
movl %esp, %ebp
push %esi
push %edi
movl 8(%ebp), %esi # pixel array offset
movl 12(%ebp), %ecx # nb of elements
movl 16(%ebp), %edi # int16[4] array of gains
prefetch (%esi)
emms
sarl $2, %ecx # process 4 pixels per loop iteration
jz .exit
movq (%edi), %mm7 # read gain array from memory
jmp .loop_gain
.align 16
.loop_gain:
prefetch 128(%esi)
movq (%esi), %mm5 # load pixel 1-2 from memory
movq 8(%esi), %mm6 # load pixel 3-4 from memory
pxor %mm0, %mm0 # zero mm0 - mm3
pxor %mm1, %mm1
pxor %mm2, %mm2
pxor %mm3, %mm3
punpcklbw %mm5, %mm0 # unpack 1st pixel into 8.8 bit ints
punpckhbw %mm5, %mm1 # unpack 2nd
punpcklbw %mm6, %mm2 # unpack 3rd
punpckhbw %mm6, %mm3 # unpack 4th
psrlw $0x1, %mm0 # shift right to clear sign bit 9.7
psrlw $0x1, %mm1
psrlw $0x1, %mm2
psrlw $0x1, %mm3
pmulhw %mm7, %mm0 # multiply 1st pixel 9.7 * 7.9 -> 16.0
pmulhw %mm7, %mm1 # multiply 2nd
pmulhw %mm7, %mm2 # multiply 3rd
pmulhw %mm7, %mm3 # multiply 4th
packuswb %mm1, %mm0 # pack & saturate to 8bit vector
movq %mm0, (%esi) # store result in memory
packuswb %mm3, %mm2 # pack & saturate to 8bit vector
movq %mm2, 8(%esi) # store result in memory
addl $16, %esi # increment source pointer
decl %ecx
jnz .loop_gain # loop
.exit:
emms
pop %edi
pop %esi
leave
ret
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