old method

Author: czurnieden

demo/test.c

@@ -494,6 +494,8 @@ static int test_mp_printf_extension(void)
       if ((characters_printed - (int)slen) != 0) {
          fprintf(stderr, "%d test_mp_print_extension: failed to print o:%zu t:%d\n",
                  idx, slen, characters_printed);
+         fprintf(stderr,"\"%s\"\n",test_strings[idx]);
+         fprintf(stderr,"\"%s\"\n",print_strings[idx]);
          goto LBL_ERR;
       }
       if (!write_only) {

mp_printf_extension.c

@@ -30,7 +30,7 @@ static void s_mp_str_reverse(char *s, int len)
    }
 }
 static const char s_mp_base64[] = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz+/";
-/* TODO: formatting. Precision and thousands separators (latter needs locale environment, so prob. not) */
+/* TODO: thousands separators (needs locale environment, so prob. not) */
 static int s_mp_print_mp_digit_binary(mp_digit number, mp_digit base, bool prefix, char *buffer)
 {
    mp_digit cp, digit;
@@ -63,14 +63,19 @@ static int s_mp_print_mp_digit_binary(mp_digit number, mp_digit base, bool prefi
    return i;
 }
 
+/* Function for the output to a stream, adjust to your needs */
+#ifndef MP_FPUTC
+#define MP_FPUTC(c, stream) fputc((c), (stream))
+#endif
+
 #include <printf.h>
 static int s_mp_print_mp_int(FILE *stream,  const struct printf_info *info,  const void *const *args)
 {
    mp_err err = MP_OKAY;
    const mp_int *a;
    char *buf, *start_buf;
-   char *prefixed_zero = "";
-   int base, len, idx = 0;
+   int base, length_number, min_width;
+   int idx = 0, fill_zeros = 0, length_printed = 0, i;
    size_t size, written, extra_len = 0u;
 
    /* Fiddle our bigint out of the argument list */
@@ -88,27 +93,6 @@ static int s_mp_print_mp_int(FILE *stream,  const struct printf_info *info,  con
       base = 10;
    }
 
-   if (mp_iszero(a)) {
-      if (info->alt == 1u) {
-         switch (base) {
-         case 2:
-            prefixed_zero = "0b0";
-            break;
-         case 8:
-            prefixed_zero = "0o0";
-            break;
-         case 16:
-            prefixed_zero = "0x0";
-            break;
-         case 64:
-            prefixed_zero = "0@0";
-            break;
-         }
-         return fprintf(stream, "%*s", (info->left ? -info->width : info->width), prefixed_zero);
-      }
-      return fprintf(stream, "%*s", (info->left ? -info->width : info->width), "0");
-   }
-
    /* Get some estimate of the size of "a" in the given base */
    if ((err = mp_radix_size_overestimate(a, base, &size)) != MP_OKAY) {
       return -1;
@@ -123,6 +107,14 @@ static int s_mp_print_mp_int(FILE *stream,  const struct printf_info *info,  con
       extra_len++;
    }
 
+   /* Minimum length, fill with leading zeros if not reached */
+   if (info->prec > 0) {
+      if (info->prec > (int)size) {
+         /* exact number is in written later */
+         size = (size_t)info->prec;
+      }
+   }
+
    buf = MP_MALLOC(size + extra_len);
    if (buf == NULL) {
       return -1;
@@ -138,6 +130,7 @@ static int s_mp_print_mp_int(FILE *stream,  const struct printf_info *info,  con
       buf--;
    }
 
+
    if ((err = mp_to_radix(a, buf, size, &written, base)) != MP_OKAY) {
       MP_FREE(start_buf, size + extra_len);
       return -1;
@@ -146,34 +139,106 @@ static int s_mp_print_mp_int(FILE *stream,  const struct printf_info *info,  con
    if (mp_isneg(a)) {
       start_buf[idx++] = '-';
    } else {
+      /* For alignment of numbers with and without a sign. */
       if (info->space) {
          start_buf[idx++] = ' ';
+         /* Always print the sign (default is for negative numbers only) */
       } else if (info->showsign) {
          start_buf[idx++] = '+';
       }
    }
 
+   /* "info->alt" holds the information if a prefix is wanted */
    if ((base != 10) && (info->alt == 1u)) {
       start_buf[idx++] = '0';
       switch (base) {
       case 2:
-         start_buf[idx] = 'b';
+         /* Non-standard extension */
+         start_buf[idx++] = 'b';
          break;
       case 8:
-         start_buf[idx] = 'o';
+         start_buf[idx++] = 'o';
          break;
       case 16:
-         start_buf[idx] = 'x';
+         start_buf[idx++] = 'x';
          break;
       case 64:
-         start_buf[idx] = '@';
+         /* Non-standard extension */
+         start_buf[idx++] = '@';
          break;
       }
    }
-   len = fprintf(stream, "%*s", (info->left ? -info->width : info->width), start_buf);
+
+   /* As mentioned above: the minus sign gets overwritten. */
+   if (mp_isneg(a)) {
+      written--;
+   }
+
+   /* Length of the number with the prefix but without the leading zeros (prec) */
+   length_number = idx + (int)written - 1;
+
+   /* Include minimum length if set*/
+   if (info->prec > length_number) {
+      min_width = info->width - info->prec;
+   } else {
+      min_width = info->width - length_number;
+   }
+
+   /* Print padding to the left for alignment to the right */
+   if (!(info->left) && (min_width > 0)) {
+      while (min_width--) {
+         if (info->pad != 0) {
+            /* TODO: The type of info->pad is wchar_t, make a note in
+                     the docs not to use a wchar_t pad */
+            MP_FPUTC((int)(info->pad),stream);
+            length_printed++;
+         } else {
+            MP_FPUTC(' ',stream);
+            length_printed++;
+         }
+      }
+   }
+
+   /* Print the prefix */
+   for (i = 0; i < idx; i++) {
+      MP_FPUTC(start_buf[i],stream);
+      length_printed++;
+   }
+
+   /* Add leading zeros if set  */
+   if (info->prec > 0) {
+      /* Prefix length, if there is any, is in idx*/
+      fill_zeros = info->prec - idx - (int)written + 1;
+      /* No truncating */
+      if (fill_zeros > 0) {
+         while (fill_zeros--) {
+            MP_FPUTC('0',stream);
+            length_printed++;
+         }
+      }
+   }
+
+   /* Print the number itself */
+   while (start_buf[idx] != '\0') {
+      MP_FPUTC(start_buf[idx++],stream);
+      length_printed++;
+   }
+
+   /* Print padding to the right for alignment to the left */
+   if ((info->left) && (min_width > 0)) {
+      while (min_width--) {
+         if (info->pad != 0) {
+            MP_FPUTC((int)(info->pad),stream);
+            length_printed++;
+         } else {
+            MP_FPUTC(' ',stream);
+            length_printed++;
+         }
+      }
+   }
 
    MP_FREE(start_buf, size + extra_len);
-   return len;
+   return length_printed;
 }
 
 #include <inttypes.h>