fdprintf.c

   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 <stdint.h>
  16 #include <unistd.h>
  17
  18 #include "fdprintf.h"
  19
  20 int stdfdin = STDIN_FILENO;
  21 int stdfdout = STDOUT_FILENO;
  22 int stdfderr = STDERR_FILENO;
  23
  24 unsigned int nextpow (unsigned int x, int base) {
  25     unsigned int n = 0;
  26     while (x) {
  27         n++;
  28         x = x / base;
  29     }
  30     return (n == 0) ? 1 : n;
  31 }
  32
  33 char *itoa (char *str, unsigned u, unsigned int sz)
  34 {
  35     unsigned int i = (sz == 0 ) ? nextpow (u, 10) : sz;
  36     char *s = str;
  37     while (i > 0) {
  38         str[i - 1] = '0' + (u % 10);
  39         u /= 10;
  40         i--;
  41         s++;
  42     }
  43     return s;
  44 }
  45
  46 /* simple fprintf function */
  47
  48 int fdprintf (int fd, const char *fmt, ...)
  49 {
  50     char buffer[1024 + 1] = { 0 };
  51     char *str = buffer;
  52
  53     va_list ap;
  54     va_start (ap, fmt);
  55     while (*fmt) {
  56         char *s;
  57         double f = 0.0;
  58         int d = 0;
  59         unsigned int u;
  60         char c = *fmt++;
  61
  62         /* copy standard char */
  63         if (c != '%') {
  64             *str++ = c;
  65         } else {
  66             int t = 0;
  67             char w = '0';
  68             int i, sz = 0;
  69             void *p = NULL;
  70
  71             /* stamp */
  72             if ((*fmt == ' ') || (*fmt == '0')) {
  73                 w = *fmt++;
  74             }
  75
  76             /* size */
  77             if ((*fmt >= '1') && (*fmt <= '9')) {
  78                 sz = *fmt++ - '0';
  79             }
  80
  81             /* process format char */
  82             switch (*fmt++) {
  83             case 'c': /* char */
  84                 c = (char) va_arg (ap, int);
  85                 *str++ = c;
  86                 break;
  87             case 'd': /* int */
  88                 d = va_arg (ap, int);
  89                 if (d < 0) {
  90                     *str++ = '-';
  91                     d = -d;
  92                 }
  93                 t = 1;
  94                 /* fall through */
  95             case 'u': /* unsigned int */
  96                 str = itoa (str, (t) ? (unsigned int)d : va_arg (ap, unsigned int), 0);
  97                 break;
  98             case 'f': /* float */
  99                 f = va_arg (ap, double);
 100                 if (f == 0) {
 101                     *str++ = '0';
 102                     break;
 103                 }
 104                 if (f < 0) {
 105                     *str++ = '-';
 106                     f = -f;
 107                 }
 108                 t = 0;
 109                 while (f > 10) {
 110                     f /= 10;
 111                     t++;
 112                 }
 113                 while (f < 1) {
 114                     f *= 10;
 115                     t--;
 116                 }
 117                 f += 1e-7;
 118                 if (f >= 10) {
 119                     f /= 10;
 120                     t++;
 121                 }
 122                 u = (int)f;
 123                 str = itoa (str, u, 0);
 124                 d = (int)((f - u) * 1e6);
 125                 if (d > 0) {
 126                     *str++ = '.';
 127                     str = itoa (str, d, 6);
 128                 }
 129                 if (t != 0) {
 130                     *str++ = 'e';
 131                     if (t < 0) {
 132                         *str++ = '-';
 133                         t = -t;
 134                     }
 135                     str = itoa (str, t, 0);
 136                 }
 137                 break;
 138             case 'p': /* pointer */
 139                 *str++ = '0';
 140                 *str++ = 'x';
 141                 w = '0';
 142                 sz = sizeof (void *) * 2;
 143                 p = va_arg (ap, void *);
 144                 /* fall through */
 145             case 'x': /* integer hexa */
 146                 if (!p) {
 147                     u = va_arg (ap, unsigned int);
 148                     if (sz == 0) {
 149                         sz = nextpow (u, 16);
 150                     }
 151                 } else {
 152                     u = (uintptr_t)p;
 153                 }
 154                 for (i = sz, t = 1; i > 0; i--) {
 155                     char x = (char)((u >> (i * 4 - 4)) & 0xf);
 156                     if ((t == 1) && (x == 0)) {
 157                         *str++ = w;
 158                     } else {
 159                         *str++ = (x > 9) ? 'a' + x - 10 : '0' + x;
 160                         t = 0;
 161                     }
 162                 }
 163                 break;
 164             case 's': /* string */
 165                 s = va_arg (ap, char *);
 166                 while (s && *s)
 167                     *str++ = *s++;
 168                 break;
 169             default:
 170                 *str++ = '?';
 171             }
 172         }
 173     }
 174     va_end (ap);
 175
 176     /* output string */
 177     int n = str - buffer;
 178     if (n < (int)sizeof (buffer) - 1) {
 179         return write (fd, buffer, n);
 180     }
 181     return 0;
 182 }
 183
 184 /* vim: set ts=4 sw=4 et: */