init commit

peak_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(signed short *in,int cnt);	
+	.global peakval_mmx
+	.type peakval_mmx,@function
+	.align 16
+peakval_mmx:
+	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
+