diff options
Diffstat (limited to 'peakval_mmx_assist.s')
| -rw-r--r-- | peakval_mmx_assist.s | 70 |
1 files changed, 70 insertions, 0 deletions
diff --git a/peakval_mmx_assist.s b/peakval_mmx_assist.s new file mode 100644 index 0000000..553cb79 --- /dev/null +++ b/peakval_mmx_assist.s @@ -0,0 +1,70 @@ +# MMX assist routines for peakval +# Copyright 2001 Phil Karn, KA9Q +# May be used under the terms of the GNU Lesser General Public License (LGPL) + + .text + +# Find peak value in signed 16-bit input samples +# int peakval_mmx_assist(signed short *in,int cnt); + .global peakval_mmx_assist + .type peakval_mmx_assist,@function + .align 16 +peakval_mmx_assist: + pushl %ebp + movl %esp,%ebp + pushl %esi + pushl %ecx + pushl %ebx + + movl 8(%ebp),%esi + movl 12(%ebp),%ecx + + pxor %mm7,%mm7 # clear peak + +1: subl $4,%ecx + jl 2f + movq (%esi),%mm0 + movq %mm0,%mm1 + psraw $15,%mm1 # mm1 = 1's if negative, 0's if positive + pxor %mm1,%mm0 # complement negatives + psubw %mm1,%mm0 # add 1 to negatives + movq %mm7,%mm6 # copy previous peak + pcmpgtw %mm0,%mm6 # ff == old peak greater + pand %mm6,%mm7 # select old peaks that are greater + pandn %mm0,%mm6 # select new values that are greater + por %mm6,%mm7 + + addl $8,%esi + jmp 1b + +2: movd %mm7,%eax + psrlq $16,%mm7 + andl $0xffff,%eax + + movd %mm7,%edx + psrlq $16,%mm7 + andl $0xffff,%edx + cmpl %edx,%eax + jnl 3f + movl %edx,%eax +3: + movd %mm7,%edx + psrlq $16,%mm7 + andl $0xffff,%edx + cmpl %edx,%eax + jnl 4f + movl %edx,%eax +4: + movd %mm7,%edx + andl $0xffff,%edx + cmpl %edx,%eax + jnl 5f + movl %edx,%eax +5: + emms + popl %ebx + popl %ecx + popl %esi + popl %ebp + ret + |