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https://opencores.org/ocsvn/openrisc_2011-10-31/openrisc_2011-10-31/trunk
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[/] [openrisc/] [trunk/] [gnu-src/] [newlib-1.17.0/] [newlib/] [libc/] [machine/] [mips/] [memset.c] - Rev 194
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/* FUNCTION <<memset>>---set an area of memory, optimized for the MIPS processors INDEX memset ANSI_SYNOPSIS #include <string.h> void *memset(const void *<[dst]>, int <[c]>, size_t <[length]>); TRAD_SYNOPSIS #include <string.h> void *memset(<[dst]>, <[c]>, <[length]>) void *<[dst]>; int <[c]>; size_t <[length]>; DESCRIPTION This function converts the argument <[c]> into an unsigned char and fills the first <[length]> characters of the array pointed to by <[dst]> to the value. RETURNS <<memset>> returns the value of <[m]>. PORTABILITY <<memset>> is ANSI C. <<memset>> requires no supporting OS subroutines. QUICKREF memset ansi pure */ #include <string.h> #ifdef __mips64 #define wordtype long long #else #define wordtype long #endif #define LBLOCKSIZE (sizeof(wordtype)) #define UNALIGNED(X) ((long)(X) & (LBLOCKSIZE - 1)) #define TOO_SMALL(LEN) ((LEN) < LBLOCKSIZE * 4) _PTR _DEFUN (memset, (m, c, n), _PTR m _AND int c _AND size_t n) { #if defined(PREFER_SIZE_OVER_SPEED) || defined(__OPTIMIZE_SIZE__) || defined(__mips16) char *s = (char *) m; while (n-- != 0) { *s++ = (char) c; } return m; #else char *s = (char *) m; int i; unsigned wordtype buffer; unsigned wordtype *aligned_addr; unsigned short *short_addr; size_t iter; if (!TOO_SMALL (n)) { int unaligned = UNALIGNED (s); /* We know that N is >= LBLOCKSIZE so we can just word align the S without having to check the length. */ if (unaligned) { while (unaligned++ < LBLOCKSIZE) *s++ = (char)c, n--; } /* S is now word-aligned so we can process the remainder in word sized chunks except for a few (< LBLOCKSIZE) bytes which might be left over at the end. */ aligned_addr = (unsigned wordtype *)s; /* Store C into each char sized location in BUFFER so that we can set large blocks quickly. */ c &= 0xff; buffer = c; if (buffer != 0) { if (LBLOCKSIZE == 4) { buffer |= (buffer << 8); buffer |= (buffer << 16); } else if (LBLOCKSIZE == 8) { buffer |= (buffer << 8); buffer |= (buffer << 16); buffer |= ((buffer << 31) << 1); } else { for (i = 1; i < LBLOCKSIZE; i++) buffer = (buffer << 8) | c; } } iter = n / (2*LBLOCKSIZE); n = n % (2*LBLOCKSIZE); while (iter > 0) { aligned_addr[0] = buffer; aligned_addr[1] = buffer; aligned_addr += 2; iter--; } if (n >= LBLOCKSIZE) { *aligned_addr++ = buffer; n -= LBLOCKSIZE; } /* Pick up the remainder with a bytewise loop. */ s = (char*)aligned_addr; } while (n > 0) { *s++ = (char)c; n--; } return m; #endif /* not PREFER_SIZE_OVER_SPEED */ }
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