liberte@uiucdcs.Uiuc.ARPA (07/12/85)
A 30% improvement in speed results by using this indexed lookup table,
trlookup, instead of doing a linear search through tr. This is for the
version of xbin.c which handles all previous BinHex formats.
Dan LaLiberte
liberte@uiucdcs.Uiuc.ARPA
ihnp4!uiucdcs!liberte
{I wont post xbin.shar unless I get 20 requests (by mail!) pronto.}
char tr[] = "!\"#$%&'()*+,-012345689@ABCDEFGHIJKLMNPQRSTUVXYZ[`abcdefhijklmpqr";
/* 0 123456789abcdef0123456789abcdef0123456789abcdef0123456789abcdef
0 1 2 3
trlookup is used to translate by direct lookup. The input character
is an index into trlookup. If the result is 0xFF, a bad char has been read.
Added by: Dan LaLiberte, liberte@uiucdcs.Uiuc.ARPA, ihnp4!uiucdcs!liberte
*/
char trlookup[83] = { 0xFF, 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06,
0x07, 0x08, 0x09, 0x0A, 0x0B, 0x0C, 0xFF, 0xFF,
0x0D, 0x0E, 0x0F, 0x10, 0x11, 0x12, 0x13, 0xFF,
0x14, 0x15, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0x16, 0x17, 0x18, 0x19, 0x1A, 0x1B, 0x1C, 0x1D,
0x1E, 0x1F, 0x20, 0x21, 0x22, 0x23, 0x24, 0xFF,
0x25, 0x26, 0x27, 0x28, 0x29, 0x2A, 0x2B, 0xFF,
0x2C, 0x2D, 0x2E, 0x2F, 0xFF, 0xFF, 0xFF, 0xFF,
0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0xFF,
0x37, 0x38, 0x39, 0x3A, 0x3B, 0x3C, 0xFF, 0xFF,
0x3D, 0x3E, 0x3F };
/* q format -- decode one byte into 6 bit binary */
get6bits()
{
register int c;
register int tc;
while (1) {
c = getc(ifp);
switch (c) {
case '\n':
case '\r':
continue;
case ':':
case EOF:
return EOF;
default:
tc = ((c-' ') < 83) ? trlookup[c-' '] : 0xff;
/* fprintf(stderr, "c = '%c' tc = %4x\n", c, tc); */
if (tc != 0xff)
return (tc);
fprintf(stderr, "bad char: '%c'\n", c);
return EOF;
}
}
}