date and time created 92/02/29 12:48:56 by bostic

SCCS-vsn: lib/libc/mips/string/bcopy.s 5.1

diff --git a/usr/src/lib/libc/mips/string/bcopy.s b/usr/src/lib/libc/mips/string/bcopy.s
new file mode 100644 (file)
index 0000000..c492064
--- /dev/null
+++ b/usr/src/lib/libc/mips/string/bcopy.s
@@ -0,0 +1,99 @@
+/*-
+ * Copyright (c) 1991 The Regents of the University of California.
+ * All rights reserved.
+ *
+ * This code is derived from software contributed to Berkeley by
+ * Ralph Campbell.
+ *
+ * %sccs.include.redist.c%
+ */
+
+#if defined(LIBC_SCCS) && !defined(lint)
+       ASMSTR("@(#)bcopy.s     5.1 (Berkeley) %G%")
+#endif /* LIBC_SCCS and not lint */
+
+#include "DEFS.h"
+
+/* bcopy(s1, s2, n) */
+
+LEAF(bcopy)
+       .set    noreorder
+       addu    t0, a0, a2              # t0 = end of s1 region
+       sltu    t1, a1, t0
+       sltu    t2, a0, a1
+       and     t1, t1, t2              # t1 = true if from < to < (from+len)
+       beq     t1, zero, forward       # non overlapping, do forward copy
+       slt     t2, a2, 12              # check for small copy
+
+       ble     a2, zero, 2f
+       addu    t1, a1, a2              # t1 = end of to region
+1:
+       lb      v0, -1(t0)              # copy bytes backwards,
+       subu    t0, t0, 1               #   doesn't happen often so do slow way
+       subu    t1, t1, 1
+       bne     t0, a0, 1b
+       sb      v0, 0(t1)
+2:
+       j       ra
+       nop
+forward:
+       bne     t2, zero, smallcpy      # do a small bcopy
+       xor     v0, a0, a1              # compare low two bits of addresses
+       and     v0, v0, 3
+       subu    a3, zero, a1            # compute # bytes to word align address
+       beq     v0, zero, aligned       # addresses can be word aligned
+       and     a3, a3, 3
+
+       beq     a3, zero, 1f
+       subu    a2, a2, a3              # subtract from remaining count
+       lwr     v0, 0(a0)               # get next 4 bytes (unaligned)
+       lwl     v0, 3(a0)
+       addu    a0, a0, a3
+       swr     v0, 0(a1)               # store 1, 2, or 3 bytes to align a1
+       addu    a1, a1, a3
+1:
+       and     v0, a2, 3               # compute number of words left
+       subu    a3, a2, v0
+       move    a2, v0
+       addu    a3, a3, a0              # compute ending address
+2:
+       lwr     v0, 0(a0)               # copy words a0 unaligned, a1 aligned
+       lwl     v0, 3(a0)
+       addu    a0, a0, 4
+       addu    a1, a1, 4
+       bne     a0, a3, 2b
+       sw      v0, -4(a1)
+       b       smallcpy
+       nop
+aligned:
+       beq     a3, zero, 1f
+       subu    a2, a2, a3              # subtract from remaining count
+       lwr     v0, 0(a0)               # copy 1, 2, or 3 bytes to align
+       addu    a0, a0, a3
+       swr     v0, 0(a1)
+       addu    a1, a1, a3
+1:
+       and     v0, a2, 3               # compute number of whole words left
+       subu    a3, a2, v0
+       move    a2, v0
+       addu    a3, a3, a0              # compute ending address
+2:
+       lw      v0, 0(a0)               # copy words
+       addu    a0, a0, 4
+       addu    a1, a1, 4
+       bne     a0, a3, 2b
+       sw      v0, -4(a1)
+smallcpy:
+       ble     a2, zero, 2f
+       addu    a3, a2, a0              # compute ending address
+1:
+       lbu     v0, 0(a0)               # copy bytes
+       addu    a0, a0, 1
+       addu    a1, a1, 1
+       bne     a0, a3, 1b
+       sb      v0, -1(a1)
+2:
+       j       ra
+       nop
+       .set    reorder
+END(bcopy)