URL
https://opencores.org/ocsvn/openrisc_2011-10-31/openrisc_2011-10-31/trunk
Subversion Repositories openrisc_2011-10-31
[/] [openrisc/] [trunk/] [gnu-src/] [newlib-1.17.0/] [newlib/] [libc/] [machine/] [mips/] [strncpy.c] - Rev 148
Go to most recent revision | Compare with Previous | Blame | View Log
/* * strncpy.S -- strncmp function. On at least some MIPS chips, you get better * code by hand unrolling the loops, and by using store words to zero the * remainder of the buffer than the default newlib C version. * * Copyright (c) 2001 Red Hat, Inc. * * The authors hereby grant permission to use, copy, modify, distribute, * and license this software and its documentation for any purpose, provided * that existing copyright notices are retained in all copies and that this * notice is included verbatim in any distributions. No written agreement, * license, or royalty fee is required for any of the authorized uses. * Modifications to this software may be copyrighted by their authors * and need not follow the licensing terms described here, provided that * the new terms are clearly indicated on the first page of each file where * they apply. */ #include <string.h> #include <stddef.h> #include <stdlib.h> #include <stdint.h> #if !defined(__GNUC__) || (__GNUC__ < 3) #define __builtin_expect(a,b) a #else #ifdef __mips64 /* Don't use limits test for the size of long, in order to allow the use of 64-bit stores on MIPS3 machines, even if -mlong32 was used. */ typedef unsigned word_type __attribute__ ((mode (DI))); #else typedef unsigned word_type __attribute__ ((mode (SI))); #endif typedef unsigned si_type __attribute__ ((mode (SI))); typedef unsigned hi_type __attribute__ ((mode (HI))); #ifndef UNROLL_FACTOR #define UNROLL_FACTOR 4 #elif (UNROLL_FACTOR != 2) && (UNROLL_FACTOR != 4) #error "UNROLL_FACTOR must be 2 or 4" #endif #endif char * strncpy (char *dst0, const char *src0, size_t count) { #if defined(PREFER_SIZE_OVER_SPEED) || defined(__OPTIMIZE_SIZE__) || defined(__mips16) || !defined(__GNUC__) || (__GNUC__ < 3) char *dst, *end; const char *src; int ch; dst = dst0; src = src0; end = dst + count; while (dst != end) { *dst++ = ch = *src++; if (__builtin_expect (ch == '\0', 0)) { while (dst != end) *dst++ = '\0'; break; } } return dst0; #else unsigned char *dst; unsigned char *dst_end; unsigned char *end; const unsigned char *src; int ch0, ch1; #if UNROLL_FACTOR > 2 int ch2, ch3; #endif int ch; int odd_bytes; size_t long_count; dst = (unsigned char *)dst0; src = (unsigned const char *)src0; /* Take care of any odd bytes in the source data because we * want to unroll where we read ahead 2 or 4 bytes at a time and then * check each byte for the null terminator. This can result in * a segfault for the case where the source pointer is unaligned, * the null terminator is in valid memory, but reading 2 or 4 bytes at a * time blindly eventually goes outside of valid memory. */ while (((uintptr_t) src & (UNROLL_FACTOR - 1)) != 0 && count > 0) { *dst++ = ch = *src++; --count; if (ch == '\0') { end = dst + count; while (dst != end) *dst++ = '\0'; return dst0; } } if (__builtin_expect (count >= 4, 1)) { odd_bytes = (count & (UNROLL_FACTOR - 1)); count -= odd_bytes; do { ch0 = src[0]; ch1 = src[1]; #if UNROLL_FACTOR > 2 ch2 = src[2]; ch3 = src[3]; #endif src += UNROLL_FACTOR; count -= UNROLL_FACTOR; dst[0] = ch0; if (ch0 == '\0') goto found_null0; dst[1] = ch1; if (ch1 == '\0') goto found_null1; #if UNROLL_FACTOR > 2 dst[2] = ch2; if (ch2 == '\0') goto found_null2; dst[3] = ch3; if (ch3 == '\0') goto found_null3; #endif dst += UNROLL_FACTOR; } while (count); /* fall through, count == 0, no null found, deal with last bytes */ count = odd_bytes; } end = dst + count; while (dst != end) { *dst++ = ch = *src++; if (ch == '\0') { while (dst != end) *dst++ = '\0'; break; } } return dst0; /* Found null byte in first byte, count has been decremented by 4, null has been stored in dst[0]. */ found_null0: count++; /* add 1 to cover remaining byte */ dst -= 1; /* adjust dst += 4 gets correct ptr */ /* fall through */ /* Found null byte in second byte, count has been decremented by 4, null has been stored in dst[1]. */ found_null1: #if UNROLL_FACTOR > 2 count++; /* add 1 to cover remaining byte */ dst -= 1; /* adjust dst += 4 gets correct ptr */ /* fall through */ /* Found null byte in third byte, count has been decremented by 4, null has been stored in dst[2]. */ found_null2: count++; /* add 1 to cover remaining byte */ dst -= 1; /* adjust dst += 4 gets correct ptr */ /* fall through */ /* Found null byte in fourth byte, count is accurate, dst has not been updated yet. */ found_null3: #endif count += odd_bytes; /* restore odd byte count */ dst += UNROLL_FACTOR; /* Zero fill remainder of the array. Unroll the loop, and use word/dword stores where we can. */ while (count && (((long)dst) & (sizeof (word_type) - 1)) != 0) { count--; *dst++ = 0; } while (count >= UNROLL_FACTOR*sizeof (word_type)) { count -= UNROLL_FACTOR*sizeof (word_type); dst += UNROLL_FACTOR*sizeof (word_type); #if UNROLL_FACTOR > 2 ((word_type *)(void *)dst)[-4] = 0; ((word_type *)(void *)dst)[-3] = 0; #endif ((word_type *)(void *)dst)[-2] = 0; ((word_type *)(void *)dst)[-1] = 0; } #if UNROLL_FACTOR > 2 if (count >= 2*sizeof (word_type)) { count -= 2*sizeof (word_type); ((word_type *)(void *)dst)[0] = 0; ((word_type *)(void *)dst)[1] = 0; dst += 2*sizeof (word_type); } #endif if (count >= sizeof (word_type)) { count -= sizeof (word_type); ((word_type *)(void *)dst)[0] = 0; dst += sizeof (word_type); } #ifdef __mips64 if (count >= sizeof (si_type)) { count -= sizeof (si_type); ((si_type *)(void *)dst)[0] = 0; dst += sizeof (si_type); } #endif if (count >= sizeof (hi_type)) { count -= sizeof (hi_type); ((hi_type *)(void *)dst)[0] = 0; dst += sizeof (hi_type); } if (count) *dst = '\0'; return dst0; #endif }
Go to most recent revision | Compare with Previous | Blame | View Log