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Set up table to help with ascii-hex -> hex conversion in advance to 

avoid testing static for every conversion.

svn path=/trunk/; revision=41900
This commit is contained in:
Martin Mathieson 2012-04-03 01:49:27 +00:00
parent b4f42921bb
commit f0798dabd1
1 changed files with 25 additions and 17 deletions
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42
wiretap/catapult_dct2000.c
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@ -141,6 +141,7 @@ static int write_stub_header(guint8 *frame_buffer, char *timestamp_string,
gchar *protocol_name, gchar *variant_name,
gchar *outhdr_name);
static guint8 hex_from_char(gchar c);
static void prepare_hex_byte_from_chars_table(void);
static guint8 hex_byte_from_chars(gchar *c);
static gchar char_from_hex(guint8 hex);
@ -178,6 +179,7 @@ catapult_dct2000_open(wtap *wth, int *err, gchar **err_info _U_)
gint firstline_length = 0;
dct2000_file_externals_t *file_externals;
static gchar linebuff[MAX_LINE_LENGTH];
static gboolean hex_byte_table_values_set = FALSE;
/* Clear errno before reading from the file */
errno = 0;
@ -199,6 +201,11 @@ catapult_dct2000_open(wtap *wth, int *err, gchar **err_info _U_)
return 0;
}
/* Make sure table is ready for use */
if (!hex_byte_table_values_set) {
prepare_hex_byte_from_chars_table();
hex_byte_table_values_set = TRUE;
}
/*********************************************************************/
/* Need entry in file_externals table */
@ -1423,29 +1430,30 @@ hex_from_char(gchar c)
return 0xff;
}
/* Extract and return a byte value from 2 ascii hex chars, starting from the given pointer */
static guint8
hex_byte_from_chars(gchar *c)
/* Table allowing fast lookup from a pair of ascii hex characters to a guint8 */
static guint8 s_tableValues[255][255];
/* Prepare table values so ready so don't need to check inside hex_byte_from_chars() */
static void prepare_hex_byte_from_chars_table(void)
{
static guchar hex_char_array[16] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
'a', 'b', 'c', 'd', 'e', 'f' };
guchar hex_char_array[16] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
'a', 'b', 'c', 'd', 'e', 'f' };
/* Populate lookup table first time */
static guint8 tableValues[255][255];
static gint tableSet = FALSE;
if (!tableSet) {
gint i, j;
for (i=0; i < 16; i++) {
for (j=0; j < 16; j++) {
tableValues[hex_char_array[i]][hex_char_array[j]] = i*16 + j;
}
gint i, j;
for (i=0; i < 16; i++) {
for (j=0; j < 16; j++) {
s_tableValues[hex_char_array[i]][hex_char_array[j]] = i*16 + j;
}
tableSet = TRUE;
}
}
/* Extract and return a byte value from 2 ascii hex chars, starting from the given pointer */
static guint8 hex_byte_from_chars(gchar *c)
{
/* Return value from quick table lookup */
return tableValues[(unsigned char)c[0]][(unsigned char)c[1]];
return s_tableValues[(unsigned char)c[0]][(unsigned char)c[1]];
}