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increase readability of encode.{c,h}

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This commit is contained in:
Eric 2025-06-13 01:03:14 +02:00
parent 44187d5618
commit 7106066261
2 changed files with 51 additions and 50 deletions
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97
encode.c
View file

@ -33,75 +33,76 @@ unsigned char asciitob64[] = {
int
encode(unsigned char *op, int olen, unsigned char *sp, int url)
encode(unsigned char *octbuf, int octbufsize, unsigned char *sxtbuf, int urlencoded)
{
int tmp;
unsigned char *table;
unsigned char *sbeg;
unsigned char *tend;
unsigned char *sxtbegin;
unsigned char *octleft;
int highorderbits;
table = (!url) ? b64toascii : b64urltoascii;
table = (!urlencoded) ? b64toascii : b64urltoascii;
sbeg = sp;
tend = op + olen - (olen % 3);
while (op < tend) {
*sp++ = table[(*op & ~3) >> 2];
tmp = (*op++ & 3) << 4;
*sp++ = table[tmp + ((*op & ~15) >> 4)];
tmp = (*op++ & 15) << 2;
*sp++ = table[tmp + ((*op & 192) >> 6)];
*sp++ = table[*op++ & ~192];
sxtbegin = sxtbuf;
octleft = octbuf + octbufsize - (octbufsize % 3);
while (octbuf < octleft) {
*sxtbuf++ = table[(*octbuf & ~3) >> 2];
highorderbits = (*octbuf++ & 3) << 4;
*sxtbuf++ = table[highorderbits + ((*octbuf & ~15) >> 4)];
highorderbits = (*octbuf++ & 15) << 2;
*sxtbuf++ = table[highorderbits + ((*octbuf & 192) >> 6)];
*sxtbuf++ = table[*octbuf++ & ~192];
}
switch (olen % 3) {
switch (octbufsize % 3) {
case 2:
*sp++ = table[(*op & ~3) >> 2];
tmp = (*op++ & 3) << 4;
*sp++ = table[tmp + ((*op & ~15) >> 4)];
*sp++ = table[(*op & 15) << 2];
*sp++ = PADDING;
*sxtbuf++ = table[(*octbuf & ~3) >> 2];
highorderbits = (*octbuf++ & 3) << 4;
*sxtbuf++ = table[highorderbits + ((*octbuf & ~15) >> 4)];
*sxtbuf++ = table[(*octbuf & 15) << 2];
*sxtbuf++ = PADDING;
break;
case 1:
*sp++ = table[(*op & ~3) >> 2];
*sp++ = table[(*op & 3) << 4];
*sp++ = PADDING;
*sp++ = PADDING;
*sxtbuf++ = table[(*octbuf & ~3) >> 2];
*sxtbuf++ = table[(*octbuf & 3) << 4];
*sxtbuf++ = PADDING;
*sxtbuf++ = PADDING;
break;
}
return sp-sbeg;
return sxtbuf-sxtbegin;
}
int
decode(unsigned char *sp, int slen, unsigned char *op)
decode(unsigned char *sxtbuf, int sxtbufsize, unsigned char *octbuf)
{
int tmp, b;
unsigned char *obeg;
unsigned char *qend;
unsigned char *octbegin;
unsigned char *sxtleft;
int highorderbits;
int loworderbits;
obeg = op;
qend = sp + slen - (slen % 4);
while (sp < qend) {
tmp = asciitob64[*sp++] << 2;
b = asciitob64[*sp++];
*op++ = tmp + ((b & ~15) >> 4);
tmp = (b & 15) << 4;
b = asciitob64[*sp++];
*op++ = tmp + ((b & ~3) >> 2);
*op++ = ((b & 3) << 6) + asciitob64[*sp++];
octbegin = octbuf;
sxtleft = sxtbuf + sxtbufsize - (sxtbufsize % 4);
while (sxtbuf < sxtleft) {
highorderbits = asciitob64[*sxtbuf++] << 2;
loworderbits = asciitob64[*sxtbuf++];
*octbuf++ = highorderbits + ((loworderbits & ~15) >> 4);
highorderbits = (loworderbits & 15) << 4;
loworderbits = asciitob64[*sxtbuf++];
*octbuf++ = highorderbits + ((loworderbits & ~3) >> 2);
*octbuf++ = ((loworderbits & 3) << 6) + asciitob64[*sxtbuf++];
}
switch (slen % 4) {
switch (sxtbufsize % 4) {
case 3:
tmp = asciitob64[*sp++] << 2;
b = asciitob64[*sp++];
*op++ = tmp + ((b & ~15) >> 4);
tmp = (b & 15) << 4;
*op++ = tmp + ((asciitob64[*sp++] & ~3) >> 2);
highorderbits = asciitob64[*sxtbuf++] << 2;
loworderbits = asciitob64[*sxtbuf++];
*octbuf++ = highorderbits + ((loworderbits & ~15) >> 4);
highorderbits = (loworderbits & 15) << 4;
*octbuf++ = highorderbits + ((asciitob64[*sxtbuf++] & ~3) >> 2);
break;
case 2:
tmp = asciitob64[*sp++] << 2;
*op++ = tmp + ((asciitob64[*sp++] & ~15) >> 4);
highorderbits = asciitob64[*sxtbuf++] << 2;
*octbuf++ = highorderbits + ((asciitob64[*sxtbuf++] & ~15) >> 4);
break;
}
return op-obeg;
return octbuf-octbegin;
}

4
encode.h
View file

@ -2,9 +2,9 @@
#define ENCODE_H
int
encode(unsigned char *op, int olen, unsigned char *sp, int url);
encode(unsigned char *octbuf, int octbufsize, unsigned char *sxtbuf, int urlencoded);
int
decode(unsigned char *sp, int slen, unsigned char *op);
decode(unsigned char *sxtbuf, int sxtbufsize, unsigned char *octbuf);
#endif