132 lines
4.8 KiB
C
132 lines
4.8 KiB
C
/*
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(C) Copyright 2001,2006,
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International Business Machines Corporation,
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Sony Computer Entertainment, Incorporated,
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Toshiba Corporation,
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All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions are met:
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* Redistributions of source code must retain the above copyright notice,
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this list of conditions and the following disclaimer.
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* Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in the
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documentation and/or other materials provided with the distribution.
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* Neither the names of the copyright holders nor the names of their
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contributors may be used to endorse or promote products derived from this
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software without specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <spu_intrinsics.h>
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#include <stddef.h>
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#include "vec_literal.h"
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/* Compare the two strings s1 and s2 of length n. Returns an integer
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* less than, equal to, or greater than zero if s1 is found, respectively,
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* to be less than, to match, or be greater than s2.
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*/
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int strncmp(const char *s1, const char *s2, size_t n)
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{
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unsigned int offset1, offset2;
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vec_int4 n_v;
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vec_uint4 cnt1_v, cnt2_v, max_cnt_v;
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vec_uint4 gt_v, lt_v, mask_v, end1_v, end2_v, end_v, neq_v;
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vec_uint4 shift_n_v, shift_eos_v, max_shift_v;
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vec_uchar16 shuffle1, shuffle2;
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vec_uchar16 data1A, data1B, data1, data2A, data2B, data2;
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vec_uchar16 *ptr1, *ptr2;
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data1 = data2 = spu_splats((unsigned char)0);
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ptr1 = (vec_uchar16 *)s1;
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ptr2 = (vec_uchar16 *)s2;
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offset1 = (unsigned int)(ptr1) & 15;
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offset2 = (unsigned int)(ptr2) & 15;
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shuffle1 = (vec_uchar16)spu_add((vec_uint4)spu_splats((unsigned char)offset1),
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VEC_LITERAL(vec_uint4, 0x00010203, 0x04050607, 0x08090A0B, 0x0C0D0E0F));
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shuffle2 = (vec_uchar16)spu_add((vec_uint4)spu_splats((unsigned char)offset2),
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VEC_LITERAL(vec_uint4, 0x00010203, 0x04050607, 0x08090A0B, 0x0C0D0E0F));
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data1A = *ptr1++;
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data2A = *ptr2++;
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n_v = spu_promote((int)n, 0);
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do {
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data1B = *ptr1++;
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data2B = *ptr2++;
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/* Quadword align each of the input strings so that
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* we operate on full quadwords.
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*/
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data1 = spu_shuffle(data1A, data1B, shuffle1);
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data2 = spu_shuffle(data2A, data2B, shuffle2);
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data1A = data1B;
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data2A = data2B;
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neq_v = spu_gather(spu_xor(spu_cmpeq(data1, data2), -1));
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end1_v = spu_gather(spu_cmpeq(data1, 0));
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end2_v = spu_gather(spu_cmpeq(data2, 0));
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end_v = spu_or(end1_v, end2_v), 0;
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n_v = spu_add(n_v, -16);
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/* Repeat until either
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* 1) the character count expired,
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* 2) a null character is discovered in one of the input strings, or
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* 3) the strings do not compare equal.
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*/
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} while (spu_extract(spu_and(spu_cmpeq(spu_or(end_v, neq_v), 0), spu_cmpgt(n_v, 0)), 0));
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/* Construct a mask to eliminate characters that are not of interest
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* in the comparison. Theses include characters that are beyond the
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* n character count and beyond the first null character.
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*/
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cnt1_v = spu_cntlz(end1_v);
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cnt2_v = spu_cntlz(end2_v);
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max_cnt_v = spu_sel(cnt1_v, cnt2_v, spu_cmpgt(cnt2_v, cnt1_v));
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mask_v = spu_splats((unsigned int)0xFFFF);
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shift_n_v = spu_andc((vector unsigned int)spu_sub(0, n_v), spu_cmpgt(n_v, -1));
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shift_eos_v = spu_sub(32, max_cnt_v);
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max_shift_v = spu_sel(shift_n_v, shift_eos_v, spu_cmpgt(shift_eos_v, shift_n_v));
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mask_v = spu_and(spu_sl(mask_v, spu_extract(max_shift_v, 0)), mask_v);
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/* Determine if greater then or less then in the case that they are
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* not equal. gt_v is either 1 (in the case s1 is greater then s2), or
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* -1 (in the case that s2 is greater then s1).
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*/
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gt_v = spu_gather(spu_cmpgt(data1, data2));
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lt_v = spu_gather(spu_cmpgt(data2, data1));
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gt_v = spu_sub(-1, spu_sl(spu_cmpgt(gt_v, lt_v), 1));
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/* Construct a mask to be applied to gt_v if the strings are discovered
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* to be equal.
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*/
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mask_v = spu_cmpeq(spu_and(neq_v, mask_v), 0);
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return (spu_extract(spu_andc(gt_v, mask_v), 0));
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}
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