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# Pure Data Packet mmx routine.
# Copyright (c) by Tom Schouten <pdp@zzz.kotnet.org>
#
# 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_s16
.type pixel_gain_s16,@function
# gain is integer, shift count is down
# void pixel_gain_s16(int *buf, int nb_8pixel_vectors, short int gain[4], unsigned long long *shift)
pixel_gain_s16:
pushl %ebp
movl %esp, %ebp
push %esi
push %edi
movl 20(%ebp), %edi
movq (%edi), %mm6 # get shift vector
movl 16(%ebp), %edi
movq (%edi), %mm7 # get gain vector
movl 8(%ebp), %esi # input array
movl 12(%ebp), %ecx # pixel count
.align 16
.loop_gain:
movq (%esi), %mm0 # load 4 pixels from memory
movq %mm0, %mm1
pmulhw %mm7, %mm1 # apply gain (s15.0) fixed point, high word
pmullw %mm7, %mm0 # low word
movq %mm0, %mm2 # copy
movq %mm1, %mm3
punpcklwd %mm1, %mm0 # unpack lsw components
punpckhwd %mm3, %mm2 # unpack msw components
psrad %mm6, %mm0 # apply signed shift
psrad %mm6, %mm2
packssdw %mm2, %mm0 # pack result & saturate
movq %mm0, (%esi) # store result
addl $8, %esi # increment source pointer
decl %ecx
jnz .loop_gain # loop
emms
pop %edi
pop %esi
leave
ret
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