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Rev | Author | Line No. | Line |
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1693 | serge | 1 | /* |
2 | FUNCTION |
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3 | < |
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4 | |||
5 | INDEX |
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6 | memset |
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7 | |||
8 | ANSI_SYNOPSIS |
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9 | #include |
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10 | void *memset(void *<[dst]>, int <[c]>, size_t <[length]>); |
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11 | |||
12 | TRAD_SYNOPSIS |
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13 | #include |
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14 | void *memset(<[dst]>, <[c]>, <[length]>) |
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15 | void *<[dst]>; |
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16 | int <[c]>; |
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17 | size_t <[length]>; |
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18 | |||
19 | DESCRIPTION |
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20 | This function converts the argument <[c]> into an unsigned |
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21 | char and fills the first <[length]> characters of the array |
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22 | pointed to by <[dst]> to the value. |
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23 | |||
24 | RETURNS |
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25 | < |
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26 | |||
27 | PORTABILITY |
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28 | < |
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29 | |||
30 | < |
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31 | |||
32 | QUICKREF |
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33 | memset ansi pure |
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34 | */ |
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35 | |||
36 | #include |
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37 | |||
38 | #define LBLOCKSIZE (sizeof(long)) |
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39 | #define UNALIGNED(X) ((long)X & (LBLOCKSIZE - 1)) |
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40 | #define TOO_SMALL(LEN) ((LEN) < LBLOCKSIZE) |
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41 | |||
42 | _PTR |
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43 | _DEFUN (memset, (m, c, n), |
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44 | _PTR m _AND |
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45 | int c _AND |
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46 | size_t n) |
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47 | { |
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48 | char *s = (char *) m; |
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49 | |||
50 | #if !defined(PREFER_SIZE_OVER_SPEED) && !defined(__OPTIMIZE_SIZE__) |
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51 | int i; |
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52 | unsigned long buffer; |
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53 | unsigned long *aligned_addr; |
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54 | unsigned int d = c & 0xff; /* To avoid sign extension, copy C to an |
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55 | unsigned variable. */ |
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56 | |||
57 | while (UNALIGNED (s)) |
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58 | { |
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59 | if (n--) |
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60 | *s++ = (char) c; |
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61 | else |
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62 | return m; |
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63 | } |
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64 | |||
65 | if (!TOO_SMALL (n)) |
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66 | { |
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67 | /* If we get this far, we know that n is large and s is word-aligned. */ |
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68 | aligned_addr = (unsigned long *) s; |
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69 | |||
70 | /* Store D into each char sized location in BUFFER so that |
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71 | we can set large blocks quickly. */ |
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72 | buffer = (d << 8) | d; |
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73 | buffer |= (buffer << 16); |
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74 | for (i = 32; i < LBLOCKSIZE * 8; i <<= 1) |
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75 | buffer = (buffer << i) | buffer; |
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76 | |||
77 | /* Unroll the loop. */ |
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78 | while (n >= LBLOCKSIZE*4) |
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79 | { |
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80 | *aligned_addr++ = buffer; |
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81 | *aligned_addr++ = buffer; |
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82 | *aligned_addr++ = buffer; |
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83 | *aligned_addr++ = buffer; |
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84 | n -= 4*LBLOCKSIZE; |
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85 | } |
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86 | |||
87 | while (n >= LBLOCKSIZE) |
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88 | { |
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89 | *aligned_addr++ = buffer; |
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90 | n -= LBLOCKSIZE; |
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91 | } |
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92 | /* Pick up the remainder with a bytewise loop. */ |
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93 | s = (char*)aligned_addr; |
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94 | } |
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95 | |||
96 | #endif /* not PREFER_SIZE_OVER_SPEED */ |
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97 | |||
98 | while (n--) |
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99 | *s++ = (char) c; |
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100 | |||
101 | return m; |
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102 | }><>=><=>>><>><>> |