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fix signed range problems with hex conversions

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Make hexval_table[] "const".  Also make sure that the accessor
function hexval() does not access the table with out-of-range
values by declaring its parameter "unsigned char", instead of
"unsigned int".

With this, gcc can just generate:

	movzbl  (%rdi), %eax
	movsbl  hexval_table(%rax),%edx
	movzbl  1(%rdi), %eax
	movsbl  hexval_table(%rax),%eax
	sall    $4, %edx
	orl     %eax, %edx

for the code to generate a byte from two hex characters.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>
This commit is contained in:
Linus Torvalds 2007-05-30 10:32:19 -07:00 committed by Junio C Hamano
parent 7faf068660
commit 192a6be2a7
2 changed files with 3 additions and 3 deletions
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4
cache.h
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@ -302,8 +302,8 @@ extern int legacy_loose_object(unsigned char *);
extern int has_pack_file(const unsigned char *sha1); extern int has_pack_file(const unsigned char *sha1);
extern int has_pack_index(const unsigned char *sha1); extern int has_pack_index(const unsigned char *sha1);
extern signed char hexval_table[256]; extern const signed char hexval_table[256];
static inline unsigned int hexval(unsigned int c) static inline unsigned int hexval(unsigned char c)
{ {
return hexval_table[c]; return hexval_table[c];
} }

2
sha1_file.c
View File

@ -32,7 +32,7 @@ const unsigned char null_sha1[20];
static unsigned int sha1_file_open_flag = O_NOATIME; static unsigned int sha1_file_open_flag = O_NOATIME;
signed char hexval_table[256] = { const signed char hexval_table[256] = {
-1, -1, -1, -1, -1, -1, -1, -1, /* 00-07 */ -1, -1, -1, -1, -1, -1, -1, -1, /* 00-07 */
-1, -1, -1, -1, -1, -1, -1, -1, /* 08-0f */ -1, -1, -1, -1, -1, -1, -1, -1, /* 08-0f */
-1, -1, -1, -1, -1, -1, -1, -1, /* 10-17 */ -1, -1, -1, -1, -1, -1, -1, -1, /* 10-17 */