1 files changed, 125 insertions, 0 deletions
diff --git a/private/crt32/string/mips/memcmpm.s b/private/crt32/string/mips/memcmpm.s
new file mode 100644
index 000000000..961939432
--- /dev/null
+++ b/private/crt32/string/mips/memcmpm.s
@@ -0,0 +1,125 @@
+/* ------------------------------------------------------------------ */
+/* | Copyright Unpublished, MIPS Computer Systems, Inc.  All Rights | */
+/* | Reserved.  This software contains proprietary and confidential | */
+/* | information of MIPS and its suppliers.  Use, disclosure or     | */
+/* | reproduction is prohibited without the prior express written   | */
+/* | consent of MIPS.                                               | */
+/* ------------------------------------------------------------------ */
+#ident "$Header"
+
+/*
+ * Copyright 1985 by MIPS Computer Systems, Inc.
+ */
+
+/* bcmp(s1, s2, n) */
+
+#include "kxmips.h"
+
+/*
+ * bcmp(src, dst, bcount)
+ *
+ * MINCMP is minimum number of byte that its worthwhile to try and
+ * align cmp into word transactions
+ *
+ * Calculating MINCMP
+ * Overhead =~ 15 instructions => 90 cycles
+ * Byte cmp =~ 38 cycles/word
+ * Word cmp =~ 17 cycles/word
+ * Breakeven =~ 16 bytes
+ */
+#define	MINCMP	16
+#define	NBPW	4
+
+LEAF_ENTRY(memcmp)
+	xor	v0,a0,a1
+	blt	a2,MINCMP,bytecmp	# too short, just byte cmp
+	and	v0,NBPW-1
+	subu	t8,zero,a0		# number of bytes til aligned
+	bne	v0,zero,unalgncmp	# src and dst not alignable
+/*
+ * src and dst can be simultaneously word aligned
+ */
+	and	t8,NBPW-1
+	subu	a2,t8
+	beq	t8,zero,wordcmp		# already aligned
+	move	v0,v1			# lw[lr] don't clear target reg
+	lwr	v0,0(a0)
+	lwr	v1,0(a1)
+	addu	a0,t8
+	addu	a1,t8
+	bne	v0,v1,cmpne
+
+/*
+ * word cmp loop
+ */
+wordcmp:
+	and	a3,a2,~(NBPW-1)
+	subu	a2,a3
+	beq	a3,zero,bytecmp
+	addu	a3,a0				# src1 endpoint
+1:	lw	v0,0(a0)
+	lw	v1,0(a1)
+	addu	a0,NBPW				# 1st BDSLOT
+	addu	a1,NBPW				# 2nd BDSLOT (asm doesn't move)
+	bne	v0,v1,cmpne
+	bne	a0,a3,1b			# at least one more word
+	b	bytecmp
+
+/*
+ * deal with simultaneously unalignable cmp by aligning one src
+ */
+unalgncmp:
+	subu	a3,zero,a1		# calc byte cnt to get src2 aligned
+	and	a3,NBPW-1
+	subu	a2,a3
+	beq	a3,zero,partaligncmp	# already aligned
+	addu	a3,a0			# src1 endpoint
+1:	lbu	v0,0(a0)
+	lbu	v1,0(a1)
+	addu	a0,1
+	addu	a1,1
+	bne	v0,v1,cmpne
+	bne	a0,a3,1b
+
+/*
+ * src unaligned, dst aligned loop
+ */
+partaligncmp:
+	and	a3,a2,~(NBPW-1)
+	subu	a2,a3
+	beq	a3,zero,bytecmp
+	addu	a3,a0
+1:
+	lwr	v0,0(a0)
+	lwl	v0,3(a0)
+	lw	v1,0(a1)
+	addu	a0,NBPW
+	addu	a1,NBPW
+	bne	v0,v1,cmpne
+	bne	a0,a3,1b
+
+/*
+ * brute force byte cmp loop
+ */
+bytecmp:
+	addu	a3,a2,a0			# src1 endpoint; BDSLOT
+	ble	a2,zero,cmpdone
+1:	lbu	v0,0(a0)
+	lbu	v1,0(a1)
+	addu	a0,1
+	addu	a1,1
+	bne	v0,v1,cmpne
+	bne	a0,a3,1b
+cmpdone:
+	move	v0,zero	
+	j	ra
+
+cmpne:
+	sltu	a2,v1,v0
+	bne	a2,zero,9f
+	li	v0,-1
+	j	ra
+9:
+	li	v0,1
+	j	ra
+.end bcmp