| 1 | /* |
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| 2 | FUNCTION |
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| 3 | <<memset>>---set an area of memory |
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| 4 | |
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| 5 | INDEX |
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| 6 | memset |
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| 7 | |
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| 8 | SYNOPSIS |
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| 9 | #include <string.h> |
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| 10 | void *memset(void *<[dst]>, int <[c]>, size_t <[length]>); |
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| 11 | |
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| 12 | DESCRIPTION |
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| 13 | This function converts the argument <[c]> into an unsigned |
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| 14 | char and fills the first <[length]> characters of the array |
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| 15 | pointed to by <[dst]> to the value. |
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| 16 | |
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| 17 | RETURNS |
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| 18 | <<memset>> returns the value of <[dst]>. |
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| 19 | |
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| 20 | PORTABILITY |
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| 21 | <<memset>> is ANSI C. |
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| 22 | |
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| 23 | <<memset>> requires no supporting OS subroutines. |
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| 24 | |
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| 25 | QUICKREF |
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| 26 | memset ansi pure |
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| 27 | */ |
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| 28 | |
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| 29 | #include <string.h> |
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| 30 | #include "local.h" |
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| 31 | |
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| 32 | #define LBLOCKSIZE (sizeof(long)) |
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| 33 | #define UNALIGNED(X) ((long)X & (LBLOCKSIZE - 1)) |
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| 34 | #define TOO_SMALL(LEN) ((LEN) < LBLOCKSIZE) |
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| 35 | |
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| 36 | void * |
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| 37 | __inhibit_loop_to_libcall |
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| 38 | memset (void *m, |
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| 39 | int c, |
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| 40 | size_t n) |
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| 41 | { |
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| 42 | char *s = (char *) m; |
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| 43 | |
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| 44 | #if !defined(PREFER_SIZE_OVER_SPEED) && !defined(__OPTIMIZE_SIZE__) |
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| 45 | unsigned int i; |
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| 46 | unsigned long buffer; |
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| 47 | unsigned long *aligned_addr; |
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| 48 | unsigned int d = c & 0xff; /* To avoid sign extension, copy C to an |
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| 49 | unsigned variable. */ |
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| 50 | |
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| 51 | while (UNALIGNED (s)) |
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| 52 | { |
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| 53 | if (n--) |
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| 54 | *s++ = (char) c; |
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| 55 | else |
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| 56 | return m; |
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| 57 | } |
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| 58 | |
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| 59 | if (!TOO_SMALL (n)) |
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| 60 | { |
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| 61 | /* If we get this far, we know that n is large and s is word-aligned. */ |
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| 62 | aligned_addr = (unsigned long *) s; |
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| 63 | |
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| 64 | /* Store D into each char sized location in BUFFER so that |
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| 65 | we can set large blocks quickly. */ |
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| 66 | buffer = (d << 8) | d; |
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| 67 | buffer |= (buffer << 16); |
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| 68 | for (i = 32; i < LBLOCKSIZE * 8; i <<= 1) |
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| 69 | buffer = (buffer << i) | buffer; |
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| 70 | |
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| 71 | /* Unroll the loop. */ |
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| 72 | while (n >= LBLOCKSIZE*4) |
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| 73 | { |
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| 74 | *aligned_addr++ = buffer; |
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| 75 | *aligned_addr++ = buffer; |
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| 76 | *aligned_addr++ = buffer; |
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| 77 | *aligned_addr++ = buffer; |
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| 78 | n -= 4*LBLOCKSIZE; |
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| 79 | } |
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| 80 | |
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| 81 | while (n >= LBLOCKSIZE) |
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| 82 | { |
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| 83 | *aligned_addr++ = buffer; |
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| 84 | n -= LBLOCKSIZE; |
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| 85 | } |
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| 86 | /* Pick up the remainder with a bytewise loop. */ |
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| 87 | s = (char*)aligned_addr; |
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| 88 | } |
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| 89 | |
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| 90 | #endif /* not PREFER_SIZE_OVER_SPEED */ |
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| 91 | |
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| 92 | while (n--) |
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| 93 | *s++ = (char) c; |
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| 94 | |
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| 95 | return m; |
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| 96 | } |
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