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Diffstat (limited to 'lib/libc/mips/string/bcopy.S')
| -rw-r--r-- | lib/libc/mips/string/bcopy.S | 127 |
1 files changed, 127 insertions, 0 deletions
diff --git a/lib/libc/mips/string/bcopy.S b/lib/libc/mips/string/bcopy.S new file mode 100644 index 0000000..3f64af5 --- /dev/null +++ b/lib/libc/mips/string/bcopy.S @@ -0,0 +1,127 @@ +/*- + * Copyright (c) 1991, 1993 + * The Regents of the University of California. All rights reserved. + * + * This code is derived from software contributed to Berkeley by + * Ralph Campbell. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * 3. All advertising materials mentioning features or use of this software + * must display the following acknowledgement: + * This product includes software developed by the University of + * California, Berkeley and its contributors. + * 4. Neither the name of the University nor the names of its contributors + * may be used to endorse or promote products derived from this software + * without specific prior written permission. + * + * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND + * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE + * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE + * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL + * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS + * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT + * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY + * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF + * SUCH DAMAGE. + */ + +#include <machine/asm.h> + +#if defined(LIBC_SCCS) + .text + .asciz "$OpenBSD$" +#endif /* LIBC_SCCS */ + +/* 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 # doesnt 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 + LWHI v0, 0(a0) # get next 4 bytes (unaligned) + LWLO v0, 3(a0) + addu a0, a0, a3 + SWHI 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: + LWHI v0, 0(a0) # copy words a0 unaligned, a1 aligned + LWLO 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 + LWHI v0, 0(a0) # copy 1, 2, or 3 bytes to align + addu a0, a0, a3 + SWHI 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) |
