improve decode time

atob() has been replaced with a lookup table, removing previous conditionals and function calls necessary to decode.
remove getsxts for better function readb
2025-05-29 16:02:45 +02:00 · 2025-05-29 13:48:49 +02:00 · 2025-05-29 00:51:00 +02:00 · 2025-05-28 23:24:05 +02:00 · 2025-05-28 20:33:16 +02:00 · 2025-05-28 17:55:13 +02:00
8 changed files with 158 additions and 132 deletions
--- a/7
+++ b/7
@ -1,13 +1,14 @@
-CFLAGS = -g -Wall -Wextra -Werror
+CC = gcc
+CFLAGS = -Og -g -Wall -Wextra -Werror

 objects = main.o input.o output.o encode.o

 b64 : $(objects)
-	cc -o b64 $(objects)
+	$(CC) -o b64 $(objects)

 main.o input.o : input.h
-main.o output.o : output.h
 main.o encode.o : encode.h
+main.o output.o : output.h

 .PHONY : clean
 clean :
--- a/encode.c
+++ b/encode.c
@ -2,99 +2,106 @@

 #define PADDING '='

-unsigned char b64[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ" \
-                      "abcdefghijklmnopqrstuvwxyz" \
-                      "0123456789" \
-                      "+/";
+static
+unsigned char b64toascii[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ" \
+                             "abcdefghijklmnopqrstuvwxyz" \
+                             "0123456789" \
+                             "+/";
+
+static
+unsigned char b64urltoascii[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ" \
+                                "abcdefghijklmnopqrstuvwxyz" \
+                                "0123456789" \
+                                "-_";
+
+static
+unsigned char asciitob64[] = {
+     0,  0,  0,  0,  0,  0,  0,  0,  0,  0,
+     0,  0,  0,  0,  0,  0,  0,  0,  0,  0,
+     0,  0,  0,  0,  0,  0,  0,  0,  0,  0,
+     0,  0,  0,  0,  0,  0,  0,  0,  0,  0,
+     0,  0,  0, 62,  0, 62,  0, 63, 52, 53,
+    54, 55, 56, 57, 58, 59, 60, 61,  0,  0,
+     0,  0,  0,  0,  0,  0,  1,  2,  3,  4,
+     5,  6,  7,  8,  9, 10, 11, 12, 13, 14,
+    15, 16, 17, 18, 19, 20, 21, 22, 23, 24,
+    25,  0,  0,  0,  0, 63,  0, 26, 27, 28,
+    29, 30, 31, 32, 33, 34, 35, 36, 37, 38,
+    39, 40, 41, 42, 43, 44, 45, 46, 47, 48,
+    49, 50, 51
+};

-unsigned char b64u[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ" \
-                       "abcdefghijklmnopqrstuvwxyz" \
-                       "0123456789" \
-                       "-_";

 int
 encode(unsigned char *op, int olen, unsigned char *sp, int url)
 {
-    int n;
-    unsigned char *sb, *enc;
+    int tmp;
+    unsigned char *table;
+    unsigned char *sbeg;
+    unsigned char *tend;

-    sb = sp;
-    enc = (!url) ? b64 : b64u;
-    switch (olen) {
-        case 3:
-            *sp++ = enc[(*op & ~3) >> 2];
-            n = (*op++ & 3) << 4;
-            *sp++ = enc[n + ((*op & ~15) >> 4)];
-            n = (*op++ & 15) << 2;
-            *sp++ = enc[n + ((*op & 192) >> 6)];
-            *sp = enc[*op & ~192];
-            break;
+    table = (!url) ? 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];
+    }
+    switch (olen % 3) {
        case 2:
-            *sp++ = enc[(*op & ~3) >> 2];
-            n = (*op++ & 3) << 4;
-            *sp++ = enc[n + ((*op & ~15) >> 4)];
-            *sp++ = enc[(*op & 15) << 2];
-            *sp = PADDING;
+            *sp++ = table[(*op & ~3) >> 2];
+            tmp = (*op++ & 3) << 4;
+            *sp++ = table[tmp + ((*op & ~15) >> 4)];
+            *sp++ = table[(*op & 15) << 2];
+            *sp++ = PADDING;
            break;
        case 1:
-            *sp++ = enc[(*op & ~3) >> 2];
-            *sp++ = enc[(*op & 3) << 4];
+            *sp++ = table[(*op & ~3) >> 2];
+            *sp++ = table[(*op & 3) << 4];
+            *sp++ = PADDING;
            *sp++ = PADDING;
-            *sp = PADDING;
            break;
    }

-    return sp-sb+1;
+    return sp-sbeg;
 }

 int
-decode(unsigned char *sp, int slen, unsigned char *op, int url)
+decode(unsigned char *sp, int slen, unsigned char *op)
 {
-    int n, b, atob(int c, int url);
-    unsigned char *ob;
+    int tmp, b;
+    unsigned char *obeg;
+    unsigned char *qend;

-    ob = op;
-    switch (slen) {
-        case 4:
-            n = atob(*sp++, url) << 2;
-            b = atob(*sp++, url);
-            *op++ = n + ((b & ~15) >> 4);
-
-            n = (b & 15) << 4;
-            b = atob(*sp++, url);
-            *op++ = n + ((b & ~3) >> 2);
-
-            *op = ((b & 3) << 6) + atob(*sp, url);
-            break;
+    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++];
+    }
+    switch (slen % 4) {
        case 3:
-            n = atob(*sp++, url) << 2;
-            b = atob(*sp++, url);
-            *op++ = n + ((b & ~15) >> 4);
-
-            n = (b & 15) << 4;
-            *op = n + ((atob(*sp, url) & ~3) >> 2);
+            tmp = asciitob64[*sp++] << 2;
+            b = asciitob64[*sp++];
+            *op++ = tmp + ((b & ~15) >> 4);
+            tmp = (b & 15) << 4;
+            *op++ = tmp + ((asciitob64[*sp++] & ~3) >> 2);
            break;
        case 2:
-            n = atob(*sp++, url) << 2;
-            *op = n + ((atob(*sp, url) & ~15) >> 4);
+            tmp = asciitob64[*sp++] << 2;
+            *op++ = tmp + ((asciitob64[*sp++] & ~15) >> 4);
            break;
    }

-    return op-ob+1;
-}
-
-int atob(int c, int url)
-{
-    if (c >= 'A' && c <= 'Z')
-        c -= 'A';
-    else if (c >= 'a' && c <= 'z')
-        c = c - 'a' + 26;
-    else if (c >= '0' && c <= '9')
-        c = c - '0' + 26 * 2;
-    else if (c == ((!url) ? '+' : '-'))
-        c = 62;
-    else
-        c = 63;
-
-    return c;
+    return op-obeg;
 }
--- a/encode.h
+++ b/encode.h
@ -1,10 +1,10 @@
-#ifndef HEADER_ENCODE
-#define HEADER_ENCODE
+#ifndef ENCODE_H
+#define ENCODE_H

 int
 encode(unsigned char *op, int olen, unsigned char *sp, int url);

 int
-decode(unsigned char *sp, int slen, unsigned char *op, int url);
+decode(unsigned char *sp, int slen, unsigned char *op);

 #endif
--- a/input.c
+++ b/input.c
@ -1,30 +1,29 @@
 #include "input.h"

-#define PADDING '='
+#define PADDING  '='

 int
-getocts(FILE *fp, unsigned char *o, int olen)
+readb(FILE *fp, unsigned char *s, int slen)
 {
-    int c, n;
+    int read, tread;
+    unsigned char *send, *sbeg;
+    unsigned char *l, *r;
    
-    n = 0;
-    while (n < olen-1 && (c = fgetc(fp)) != EOF)
-        o[n++] = c;
+    read = tread = 0;
+    sbeg = l = r = s;
+    while (tread < slen && (read = fread(l, sizeof(*l), slen-tread, fp))) {
+        tread += read;
+        send = s + tread;
+        for (r = l; r < send; ++r)
+            if (*r != '\n')
+                *l++ = *r;
+        tread -= r - l;
+        if (l > sbeg) {
+            for (--l; *l == PADDING; --l)
+                ;
+            ++l;
+        }
+    }

-    return n;
-}
-
-int
-getsxts(FILE *fp, unsigned char *s, int slen)
-{
-    int c, n, pad;
-
-    n = pad = 0;
-    while (n < slen-1 && (c = fgetc(fp)) != EOF && c != PADDING)
-        if (c != '\n')
-            s[n++] = c;
-    while (n+pad < slen-1)
-        s[n+pad++] = PADDING;
-
-    return n;
+    return l-sbeg;
 }
--- a/input.h
+++ b/input.h
@ -1,12 +1,9 @@
-#ifndef HEADER_INPUT
-#define HEADER_INPUT
+#ifndef INPUT_H
+#define INPUT_H

 #include <stdio.h>

 int
-getocts(FILE *fp, unsigned char *o, int olen);
-
-int
-getsxts(FILE *fp, unsigned char *s, int slen);
+readb(FILE *fp, unsigned char *s, int slen);

 #endif
--- a/main.c
+++ b/main.c
@ -4,20 +4,21 @@
 #include "output.h"
 #include "encode.h"

-#define OBUFSIZE 4
-#define SBUFSIZE 5
+#define OCTETBUF  1500
+#define SXTETBUF  2000

-unsigned char obuf[OBUFSIZE];
-unsigned char sbuf[SBUFSIZE];
+unsigned char obuf[OCTETBUF];
+unsigned char sbuf[SXTETBUF];

 int
 main(int argc, char *argv[])
 {
-    int c, n, l;
+    int c, n, last;
    int dec, url, hlp, wrp;
-    char *prog = *argv;
    FILE *in, *out;
+    char *prog;

+    prog = *argv;
    dec = url = hlp = wrp = 0;
    while (--argc > 0 && (*++argv)[0] == '-')
        while ((c = *++argv[0]))
@ -42,6 +43,7 @@ main(int argc, char *argv[])
    if (hlp) {
        fprintf(stdout, "Usage: %s -duhw infile outfile\n", prog);
    } else {
+        in = out = NULL;
        if (argc >= 1 && (in = fopen(*argv, "r")) == NULL) {
            fprintf(stderr, "%s: can't open %s\n", prog, *argv);
            exit(EXIT_FAILURE);
@ -51,22 +53,23 @@ main(int argc, char *argv[])
            exit(EXIT_FAILURE);
        }
        if (dec) {
-            while ((n = getsxts((argc >= 1) ? in : stdin, sbuf, SBUFSIZE))) {
-                n = decode(sbuf, n, obuf, url);
-                fwrite(obuf, sizeof(*obuf), n, (argc == 2) ? out : stdout);
+            while ((n = readb((in) ? in : stdin, sbuf, SXTETBUF))) {
+                n = decode(sbuf, n, obuf);
+                fwrite(obuf, sizeof(*obuf), n, (out) ? out : stdout);
            }
+        } else if (wrp) {
+            last = 0;
+            while ((n = fread(obuf, sizeof(*obuf), OCTETBUF, (in) ? in : stdin))) {
+                n = encode(obuf, n, sbuf, url);
+                last = printw((out) ? out : stdout, sbuf, n);
+            }
+            if (last != '\n')
+                fprintf((out) ? out : stdout, "\n");
        } else {
-            while ((n = getocts((argc >= 1) ? in : stdin, obuf, OBUFSIZE))) {
-                if (wrp) {
-                    n = encode(obuf, n, sbuf, url);
-                    l = printw((argc == 2) ? out : stdout, sbuf, n);
-                } else {
-                    encode(obuf, n, sbuf, url);
-                    fprintf((argc == 2) ? out : stdout, "%s", sbuf);
-                }
+            while ((n = fread(obuf, sizeof(*obuf), OCTETBUF, (in) ? in : stdin))) {
+                n = encode(obuf, n, sbuf, url);
+                fwrite(sbuf, sizeof(*sbuf), n, (out) ? out : stdout);
            }
-            if (wrp && l != '\n')
-                fprintf((argc == 2) ? out : stdout, "\n");
        }
        if (in)
            fclose(in);
--- a/output.c
+++ b/output.c
@ -8,11 +8,30 @@ printw(FILE *fp, unsigned char *s, int slen)
    static int col;
    int c;

-    while (slen--) {
-        fputc((c = *s++), fp);
-        ++col;
-        if (!(col %= WRAPCOL))
-            fputc((c = '\n'), fp);
+    c = '\n';
+    if (col) {
+        if (slen >= WRAPCOL-col) {
+            fwrite(s, sizeof(*s), WRAPCOL-col, fp);
+            s += WRAPCOL-col;
+            slen -= WRAPCOL-col;
+            col = 0;
+            fputc('\n', fp);
+        } else {
+            fwrite(s, sizeof(*s), slen, fp);
+            s += slen;
+            col += slen;
+            slen -= slen;
+            c = *(s+slen-1);
+        }
+    }
+    for (; slen >= WRAPCOL; slen -= WRAPCOL, s += WRAPCOL) {
+        fwrite(s, sizeof(*s), WRAPCOL, fp);
+        fputc('\n', fp);
+    }
+    if (slen > 0) {
+        fwrite(s, sizeof(*s), slen, fp);
+        col += slen;
+        c = *(s+slen-1);
    }

    return c;
--- a/output.h
+++ b/output.h
@ -1,5 +1,5 @@
-#ifndef HEADER_OUTPUT
-#define HEADER_OUTPUT
+#ifndef OUTPUT_H
+#define OUTPUT_H

 #include <stdio.h>
Author	SHA1	Message	Date
Eric	aacf2324c7	improve decode time atob() has been replaced with a lookup table, removing previous conditionals and function calls necessary to decode.	2025-05-29 16:02:45 +02:00
Eric	debab62506	remove getsxts for better function readb Decoding input is read faster now. With this, all options have been tuned to a reasonable degree.	2025-05-29 13:48:49 +02:00
Eric	0a4a98390d	improve printw to write faster Now all encoding options are faster.	2025-05-29 00:51:00 +02:00
Eric	f0577d8ea0	decrease encode time The functions encode and decode are now capable of processing larger buffers with less conditional logic. Input and output functions need to follow suit to make better use of this next. Encode without line wrapping already makes use of these improvements, because input and output are now entirely handled by <stdio.h> functions.	2025-05-28 23:24:05 +02:00
Eric	3194981825	repair Makefile to include -g in CFLAGS again	2025-05-28 20:33:16 +02:00
Eric	4e8bb86ddd	change Makefile to be stricter -Og enables better detection of bugs that would only occur in optimized compilations and allows for slightly lesser than -O1 optimization that does not interfere with debugging.	2025-05-28 17:55:13 +02:00
Eric	733a013ee7	remove bugs related to uninitialized variables These bugs became visible when using optimization options. They were either not present unoptimized or very unlikely to occur. However, given the options, the resulting program would behave incorrectly and reliably break under all circumstances. The makefile will see the intended changes accordingly in the following commit to ensure compatibility.	2025-05-28 17:31:07 +02:00
Eric	fa5095133a	remove buffer size dependency from input functions This should've been part of 848c37, when buffers were unwired from input functions. Now buffer size is also no longer supplied in function calls but assumed. It is up to the caller to provide appropriately sized buffers.	2025-05-27 18:37:48 +02:00
Eric	b76c50a91b	change header macro names to be more idiomatic	2025-05-27 15:14:55 +02:00