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| /*
| * Copyright (C) 2004, 2007-2010, 2011-2014 Synopsys, Inc. All rights reserved.
| *
| * SPDX-License-Identifier: GPL-2.0+
| */
|
| /*
| * This is optimized primarily for the ARC700.
| * It would be possible to speed up the loops by one cycle / word
| * respective one cycle / byte by forcing double source 1 alignment, unrolling
| * by a factor of two, and speculatively loading the second word / byte of
| * source 1; however, that would increase the overhead for loop setup / finish,
| * and strcmp might often terminate early.
| */
|
| .global strcmp
| .align 4
| strcmp:
| or %r2, %r0, %r1
| bmsk_s %r2, %r2, 1
| brne %r2, 0, .Lcharloop
| mov_s %r12, 0x01010101
| ror %r5, %r12
| .Lwordloop:
| ld.ab %r2, [%r0, 4]
| ld.ab %r3, [%r1, 4]
| nop_s
| sub %r4, %r2, %r12
| bic %r4, %r4, %r2
| and %r4, %r4, %r5
| brne %r4, 0, .Lfound0
| breq %r2 ,%r3, .Lwordloop
| #ifdef __LITTLE_ENDIAN__
| xor %r0, %r2, %r3 /* mask for difference */
| sub_s %r1, %r0, 1
| bic_s %r0, %r0, %r1 /* mask for least significant difference bit */
| sub %r1, %r5, %r0
| xor %r0, %r5, %r1 /* mask for least significant difference byte */
| and_s %r2, %r2, %r0
| and_s %r3, %r3, %r0
| #endif /* _ENDIAN__ */
| cmp_s %r2, %r3
| mov_s %r0, 1
| j_s.d [%blink]
| bset.lo %r0, %r0, 31
|
| .balign 4
| #ifdef __LITTLE_ENDIAN__
| .Lfound0:
| xor %r0, %r2, %r3 /* mask for difference */
| or %r0, %r0, %r4 /* or in zero indicator */
| sub_s %r1, %r0, 1
| bic_s %r0, %r0, %r1 /* mask for least significant difference bit */
| sub %r1, %r5, %r0
| xor %r0, %r5, %r1 /* mask for least significant difference byte */
| and_s %r2, %r2, %r0
| and_s %r3, %r3, %r0
| sub.f %r0, %r2, %r3
| mov.hi %r0, 1
| j_s.d [%blink]
| bset.lo %r0, %r0, 31
| #else /* __BIG_ENDIAN__ */
| /*
| * The zero-detection above can mis-detect 0x01 bytes as zeroes
| * because of carry-propagateion from a lower significant zero byte.
| * We can compensate for this by checking that bit0 is zero.
| * This compensation is not necessary in the step where we
| * get a low estimate for r2, because in any affected bytes
| * we already have 0x00 or 0x01, which will remain unchanged
| * when bit 7 is cleared.
| */
| .balign 4
| .Lfound0:
| lsr %r0, %r4, 8
| lsr_s %r1, %r2
| bic_s %r2, %r2, %r0 /* get low estimate for r2 and get ... */
| bic_s %r0, %r0, %r1 /* <this is the adjusted mask for zeros> */
| or_s %r3, %r3, %r0 /* ... high estimate r3 so that r2 > r3 will */
| cmp_s %r3, %r2 /* ... be independent of trailing garbage */
| or_s %r2, %r2, %r0 /* likewise for r3 > r2 */
| bic_s %r3, %r3, %r0
| rlc %r0, 0 /* r0 := r2 > r3 ? 1 : 0 */
| cmp_s %r2, %r3
| j_s.d [%blink]
| bset.lo %r0, %r0, 31
| #endif /* _ENDIAN__ */
|
| .balign 4
| .Lcharloop:
| ldb.ab %r2,[%r0,1]
| ldb.ab %r3,[%r1,1]
| nop_s
| breq %r2, 0, .Lcmpend
| breq %r2, %r3, .Lcharloop
| .Lcmpend:
| j_s.d [%blink]
| sub %r0, %r2, %r3
|
|
