Convert hex digits more systematically

This makes the code a bit smaller and presumably faster, as
it substitutes a single lookup for conditional jumps.
* src/character.c (hexdigit): New constant.
(syms_of_character) [HEXDIGIT_IS_CONST]: Initialize it.
* src/character.h (HEXDIGIT_CONST, HEXDIGIT_IS_CONST): New macros.
(hexdigit): New decl.
(char_hexdigit): New inline function.
* src/charset.c: Do not include c-ctype.h.
* src/charset.c (read_hex):
* src/editfns.c (styled_format):
* src/image.c (xbm_scan):
* src/lread.c (read_escape):
* src/regex.c (ISXDIGIT) [emacs]:
Use char_hexdigit insted of doing it by hand.

1 files changed, 2 insertions, 7 deletions

diff --git a/src/image.c b/src/image.c
index 07c4769e9e3..6b748ba2af6 100644
--- a/src/image.c
+++ b/src/image.c
@@ -2595,13 +2595,8 @@ xbm_scan (char **s, char *end, char *sval, int *ival)
               while (*s < end)
                 {
                   c = *(*s)++;
-                  if (c_isdigit (c))
-                    digit = c - '0';
-                  else if (c >= 'a' && c <= 'f')
-                    digit = c - 'a' + 10;
-                  else if (c >= 'A' && c <= 'F')
-                    digit = c - 'A' + 10;
-                  else
+                  digit = char_hexdigit (c);
+                  if (digit < 0)
                     break;
                   value = 16 * value + digit;
                 }