1 files changed, 105 insertions, 0 deletions
diff --git a/private/crt32/string/mips/memsetm.s b/private/crt32/string/mips/memsetm.s
new file mode 100644
index 000000000..a53f8f0a1
--- /dev/null
+++ b/private/crt32/string/mips/memsetm.s
@@ -0,0 +1,105 @@
+/* --------------------------------------------------- */
+/* | Copyright (c) 1986 MIPS Computer Systems, Inc.  | */
+/* | All Rights Reserved.                            | */
+/* --------------------------------------------------- */
+/* $Revision: 1.3 $ */
+
+/*
+ * char * 
+ * memset(s, c, n)
+ * 	register char * s;
+ * 	register c, n;
+ * {
+ * 	register char * p = s;
+ * 
+ * 	while (--n >= 0)
+ * 		*s++ = c;
+ * 
+ * 	return (p);
+ * }
+ */
+
+/*
+ * Copyright 1986 by MIPS Computer Systems, Inc.
+ */
+
+#include <kxmips.h>
+
+#define	NBPW	4
+
+/*
+ * memset(dst, c, bcount)
+ * set block of memory with blanks
+ *
+ * Calculating MINSET, assuming 10% cache-miss on non-loop code:
+ * Overhead =~ 18 instructions => 28 (30) cycles
+ * Byte set =~ 12 (24) cycles/word for 08M44 (08V11)
+ * Word set =~ 3 (5) cycles/word for 08M44 (08V11)
+ * If I-cache-miss nears 0, MINSET ==> 4 bytes; otherwise, times are:
+ * breakeven (MEM) = 28 / (12 - 3) =~ 3 words
+ * breakeven (VME) = 30 / (24 - 5)  =~ 1.5 words
+ * Since the overhead is pessimistic (worst-case alignment), and many calls
+ * will be for well-aligned data, and since Word-set at least leaves
+ * the set in the cache, we shade these values (6-12) down to 8 bytes
+ */
+#define	MINSET	8
+
+/* It turns out better to think of lwl/lwr and swl/swr as
+   smaller-vs-bigger address rather than left-vs-right.
+   Such a representation makes the code endian-independent. */
+
+#define LWS lwr
+#define LWB lwl
+#define SWS swr
+#define SWB swl
+
+LEAF_ENTRY(memset)
+	move	v0,a0			# return first argument; BDSLOT
+	blt	a2,MINSET,byteset
+	subu	v1,zero,a0		# number of bytes til aligned; BDSLOT
+	beq	a1,$0,1f		# make memset(s, 0, n) faster
+	sll	t0,a1,8
+	or	a1,t0
+	sll	t0,a1,16
+	or	a1,t0
+1:	and	v1,NBPW-1
+	subu	a2,v1			# adjust count; BDSLOT
+	beq	v1,zero,blkset		# already aligned
+	SWS	a1,0(a0)
+	addu	a0,v1
+
+/*
+ * set 8 byte, aligned block (no point in unrolling further,
+ * since maximum write rate in M/500 is two cycles/word write)
+ */
+blkset:
+	and	t0,a2,NBPW+NBPW-1	# count after by-8-byte loop done
+	subu	a3,a2,t0		# total in 8 byte chunks; BDSLOT
+	beq	a2,t0,wordset		# less than 8 bytes to set
+	addu	a3,a0			# dst endpoint
+1:	addu	a0,NBPW+NBPW
+	sw	a1,-NBPW-NBPW(a0)
+	sw	a1,-NBPW(a0)
+	bne	a0,a3,1b
+	move	a2,t0			# set end-of loop count
+
+/*
+ * do a word (if required) this is not a loop since loop above
+ * guarantees that at most one word must be written here.
+ */
+wordset:
+	and	t0,a2,NBPW		# count after by-word non-loop done
+	subu	a2,t0			# adjust count; BDSLOT
+	beq	t0,zero,byteset		# less than word to set
+	sw	a1,0(a0)
+	addu	a0,NBPW
+
+byteset:
+	addu	a3,a2,a0		# dst endpoint; BDSLOT
+	ble	a2,zero,setdone
+1:	addu	a0,1
+	sb	a1,-1(a0)
+	bne	a0,a3,1b
+setdone:
+	j	ra
+.end memset