| 1 | /* |
| 2 | File name : fprintf.c |
| 3 | Date of creation : 05/12/2022 |
| 4 | Version : 1.0 |
| 5 | Copyright : Soft'n'design |
| 6 | Author : Laurent Mazet <mazet@softndesign.org> |
| 7 | |
| 8 | Description : This file contains embedded printf |
| 9 | |
| 10 | History : |
| 11 | - initial version |
| 12 | */ |
| 13 | |
| 14 | #include <stdarg.h> |
| 15 | #include <stddef.h> |
| 16 | #include <stdio.h> |
| 17 | |
| 18 | inline unsigned int nextpow (unsigned int x, int base) { |
| 19 | unsigned int n = 0; |
| 20 | while (x) { |
| 21 | n++; |
| 22 | x = x / base; |
| 23 | } |
| 24 | return (n == 0) ? 1 : n; |
| 25 | } |
| 26 | |
| 27 | /* simple fprintf function */ |
| 28 | |
| 29 | size_t myfprintf (FILE *fid, const char *fmt, ...) |
| 30 | { |
| 31 | char buffer[1024 + 1] = { 0 }; |
| 32 | char *str = buffer; |
| 33 | |
| 34 | va_list ap; |
| 35 | va_start (ap, fmt); |
| 36 | while (*fmt) { |
| 37 | char *s; |
| 38 | int d = 0; |
| 39 | unsigned int u; |
| 40 | char c = *fmt++; |
| 41 | |
| 42 | /* copy standard char */ |
| 43 | if (c != '%') { |
| 44 | *str++ = c; |
| 45 | } else { |
| 46 | int t = 0; |
| 47 | char w = '0'; |
| 48 | size_t i, sz = 0; |
| 49 | void *p = NULL; |
| 50 | |
| 51 | /* stamp */ |
| 52 | if ((*fmt == ' ') || (*fmt == '0')) { |
| 53 | w = *fmt++; |
| 54 | } |
| 55 | |
| 56 | /* size */ |
| 57 | if ((*fmt >= '1') && (*fmt <= '9')) { |
| 58 | sz = *fmt++ - '0'; |
| 59 | } |
| 60 | |
| 61 | /* process format char */ |
| 62 | switch (*fmt++) { |
| 63 | case 'c': /* char */ |
| 64 | c = (char) va_arg (ap, int); |
| 65 | *str++ = c; |
| 66 | break; |
| 67 | case 'd': /* int */ |
| 68 | d = va_arg (ap, int); |
| 69 | if (d < 0) { |
| 70 | *str++ = '-'; |
| 71 | d = -d; |
| 72 | } |
| 73 | t = 1; |
| 74 | /* fall through */ |
| 75 | case 'u': /* unsigned int */ |
| 76 | u = (t) ? (unsigned int)d : va_arg (ap, unsigned int); |
| 77 | for (i = nextpow (u, 10), s = str; i > 0; i--, s++) { |
| 78 | str[i - 1] = '0' + (u % 10); |
| 79 | u /= 10; |
| 80 | } |
| 81 | str = s; |
| 82 | break; |
| 83 | case 'p': /* pointer */ |
| 84 | *str++ = '0'; |
| 85 | *str++ = 'x'; |
| 86 | w = '0'; |
| 87 | sz = sizeof (void *) * 2; |
| 88 | p = va_arg (ap, void *); |
| 89 | /* fall through */ |
| 90 | case 'x': /* integer hexa */ |
| 91 | if (!p) { |
| 92 | u = va_arg (ap, unsigned int); |
| 93 | p = (void *)u; |
| 94 | if (sz == 0) { |
| 95 | sz = nextpow (u, 16); |
| 96 | } |
| 97 | } |
| 98 | for (i = sz, t = 1; i > 0; i--) { |
| 99 | char x = (char)(((uintptr_t)p >> (i * 4 - 4)) & 0xf); |
| 100 | if ((t == 1) && (x == 0)) { |
| 101 | *str++ = w; |
| 102 | } else { |
| 103 | *str++ = (x > 9) ? 'a' + x - 10 : '0' + x; |
| 104 | t = 0; |
| 105 | } |
| 106 | } |
| 107 | break; |
| 108 | case 's': /* string */ |
| 109 | s = va_arg (ap, char *); |
| 110 | while (s && *s) |
| 111 | *str++ = *s++; |
| 112 | break; |
| 113 | default: |
| 114 | *str++ = '?'; |
| 115 | } |
| 116 | } |
| 117 | } |
| 118 | va_end (ap); |
| 119 | |
| 120 | /* output string */ |
| 121 | size_t n = str - buffer; |
| 122 | if (n < sizeof (buffer) - 1) { |
| 123 | fwrite (buffer, n, 1, fid); |
| 124 | return n; |
| 125 | } |
| 126 | return 0; |
| 127 | } |
| 128 | |
| 129 | /* vim: set ts=4 sw=4 et: */ |