remove getsxts for better function readb

Decoding input is read faster now.
With this, all options have been tuned to a reasonable degree.

input.c

@@ -1,19 +1,24 @@
 #include "input.h"
 
 #define PADDING  '='
-#define SXTETBUF  4
 
 int
-getsxts(FILE *fp, unsigned char *s)
+readb(FILE *fp, unsigned char *s, int slen)
 {
-    int c, n, pad;
+    unsigned char *send;
+    unsigned char *sbeg;
+    unsigned char *l, *r;
+    
+    sbeg = s;
+    send = s + fread(s, sizeof(*s), slen, fp);
+    for (l = r = sbeg; r < send; ++r)
+        if (*r != '\n')
+            *l++ = *r;
+    if (l > sbeg) {
+        for (--l; *l == PADDING; --l)
+            ;
+        ++l;
+    }
 
-    n = pad = 0;
-    while (n < SXTETBUF && (c = fgetc(fp)) != EOF && c != PADDING)
-        if (c != '\n')
-            s[n++] = c;
-    while (n+pad < SXTETBUF)
-        s[n+pad++] = PADDING;
-
-    return n;
+    return l-sbeg;
 }

input.h

@@ -4,6 +4,6 @@
 #include <stdio.h>
 
 int
-getsxts(FILE *fp, unsigned char *s);
+readb(FILE *fp, unsigned char *s, int slen);
 
 #endif

main.c

@@ -53,7 +53,7 @@ main(int argc, char *argv[])
             exit(EXIT_FAILURE);
         }
         if (dec) {
-            while ((n = getsxts((in) ? in : stdin, sbuf))) {
+            while ((n = readb((in) ? in : stdin, sbuf, SXTETBUF))) {
                 n = decode(sbuf, n, obuf, url);
                 fwrite(obuf, sizeof(*obuf), n, (out) ? out : stdout);
             }