improve decode time
atob() has been replaced with a lookup table, removing previous conditionals and function calls necessary to decode.
This commit is contained in:
parent
debab62506
commit
aacf2324c7
3 changed files with 44 additions and 40 deletions
76
encode.c
76
encode.c
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@ -2,15 +2,35 @@
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#define PADDING '='
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unsigned char b64[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ" \
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"abcdefghijklmnopqrstuvwxyz" \
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"0123456789" \
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"+/";
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static
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unsigned char b64toascii[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ" \
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"abcdefghijklmnopqrstuvwxyz" \
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"0123456789" \
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"+/";
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static
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unsigned char b64urltoascii[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ" \
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"abcdefghijklmnopqrstuvwxyz" \
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"0123456789" \
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"-_";
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static
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unsigned char asciitob64[] = {
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 62, 0, 62, 0, 63, 52, 53,
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54, 55, 56, 57, 58, 59, 60, 61, 0, 0,
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0, 0, 0, 0, 0, 0, 1, 2, 3, 4,
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5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
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15, 16, 17, 18, 19, 20, 21, 22, 23, 24,
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25, 0, 0, 0, 0, 63, 0, 26, 27, 28,
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29, 30, 31, 32, 33, 34, 35, 36, 37, 38,
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39, 40, 41, 42, 43, 44, 45, 46, 47, 48,
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49, 50, 51
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};
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unsigned char b64url[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ" \
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"abcdefghijklmnopqrstuvwxyz" \
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"0123456789" \
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"-_";
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int
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encode(unsigned char *op, int olen, unsigned char *sp, int url)
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@ -20,7 +40,7 @@ encode(unsigned char *op, int olen, unsigned char *sp, int url)
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unsigned char *sbeg;
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unsigned char *tend;
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table = (!url) ? b64 : b64url;
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table = (!url) ? b64toascii : b64urltoascii;
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sbeg = sp;
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tend = op + olen - (olen % 3);
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@ -52,52 +72,36 @@ encode(unsigned char *op, int olen, unsigned char *sp, int url)
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}
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int
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decode(unsigned char *sp, int slen, unsigned char *op, int url)
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decode(unsigned char *sp, int slen, unsigned char *op)
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{
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int tmp, b, atob(int c, int url);
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int tmp, b;
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unsigned char *obeg;
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unsigned char *qend;
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obeg = op;
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qend = sp + slen - (slen % 4);
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while (sp < qend) {
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tmp = atob(*sp++, url) << 2;
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b = atob(*sp++, url);
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tmp = asciitob64[*sp++] << 2;
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b = asciitob64[*sp++];
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*op++ = tmp + ((b & ~15) >> 4);
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tmp = (b & 15) << 4;
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b = atob(*sp++, url);
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b = asciitob64[*sp++];
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*op++ = tmp + ((b & ~3) >> 2);
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*op++ = ((b & 3) << 6) + atob(*sp++, url);
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*op++ = ((b & 3) << 6) + asciitob64[*sp++];
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}
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switch (slen % 4) {
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case 3:
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tmp = atob(*sp++, url) << 2;
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b = atob(*sp++, url);
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tmp = asciitob64[*sp++] << 2;
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b = asciitob64[*sp++];
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*op++ = tmp + ((b & ~15) >> 4);
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tmp = (b & 15) << 4;
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*op++ = tmp + ((atob(*sp++, url) & ~3) >> 2);
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*op++ = tmp + ((asciitob64[*sp++] & ~3) >> 2);
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break;
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case 2:
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tmp = atob(*sp++, url) << 2;
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*op++ = tmp + ((atob(*sp++, url) & ~15) >> 4);
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tmp = asciitob64[*sp++] << 2;
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*op++ = tmp + ((asciitob64[*sp++] & ~15) >> 4);
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break;
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}
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return op-obeg;
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}
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int atob(int c, int url)
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{
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if (c >= 'A' && c <= 'Z')
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c -= 'A';
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else if (c >= 'a' && c <= 'z')
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c = c - 'a' + 26;
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else if (c >= '0' && c <= '9')
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c = c - '0' + 26 * 2;
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else if (c == ((!url) ? '+' : '-'))
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c = 62;
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else
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c = 63;
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return c;
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}
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2
encode.h
2
encode.h
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@ -5,6 +5,6 @@ int
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encode(unsigned char *op, int olen, unsigned char *sp, int url);
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int
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decode(unsigned char *sp, int slen, unsigned char *op, int url);
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decode(unsigned char *sp, int slen, unsigned char *op);
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#endif
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6
main.c
6
main.c
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@ -4,8 +4,8 @@
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#include "output.h"
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#include "encode.h"
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#define OCTETBUF 300
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#define SXTETBUF 400
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#define OCTETBUF 1500
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#define SXTETBUF 2000
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unsigned char obuf[OCTETBUF];
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unsigned char sbuf[SXTETBUF];
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@ -54,7 +54,7 @@ main(int argc, char *argv[])
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}
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if (dec) {
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while ((n = readb((in) ? in : stdin, sbuf, SXTETBUF))) {
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n = decode(sbuf, n, obuf, url);
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n = decode(sbuf, n, obuf);
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fwrite(obuf, sizeof(*obuf), n, (out) ? out : stdout);
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}
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} else if (wrp) {
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