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, 6 insertions, 19 deletions

diff --git a/src/lread.c b/src/lread.c
index 182f96223a5..7c554ba8536 100644
--- a/src/lread.c
+++ b/src/lread.c
@@ -2426,25 +2426,13 @@ read_escape (Lisp_Object readcharfun, bool stringp)
         while (1)
           {
             c = READCHAR;
-            if (c >= '0' && c <= '9')
-              {
-                i *= 16;
-                i += c - '0';
-              }
-            else if ((c >= 'a' && c <= 'f')
-                     || (c >= 'A' && c <= 'F'))
-              {
-                i *= 16;
-                if (c >= 'a' && c <= 'f')
-                  i += c - 'a' + 10;
-                else
-                  i += c - 'A' + 10;
-              }
-            else
+            int digit = char_hexdigit (c);
+            if (digit < 0)
               {
                 UNREAD (c);
                 break;
               }
+            i = (i << 4) + digit;
             /* Allow hex escapes as large as ?\xfffffff, because some
                packages use them to denote characters with modifiers.  */
             if ((CHAR_META | (CHAR_META - 1)) < i)
@@ -2474,11 +2462,10 @@ read_escape (Lisp_Object readcharfun, bool stringp)
             c = READCHAR;
             /* `isdigit' and `isalpha' may be locale-specific, which we don't
                want.  */
-            if      (c >= '0' && c <= '9')  i = (i << 4) + (c - '0');
-            else if (c >= 'a' && c <= 'f')  i = (i << 4) + (c - 'a') + 10;
-            else if (c >= 'A' && c <= 'F')  i = (i << 4) + (c - 'A') + 10;
-            else
+            int digit = char_hexdigit (c);
+            if (digit < 0)
               error ("Non-hex digit used for Unicode escape");
+            i = (i << 4) + digit;
           }
         if (i > 0x10FFFF)
           error ("Non-Unicode character: 0x%x", i);