Merge branch 'dev' of hiajen-forgejo:/penpen/b64 into dev

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

input.c

@@ -5,19 +5,24 @@
 int
 readb(FILE *fp, unsigned char *s, int slen)
 {
-    unsigned char *send;
-    unsigned char *sbeg;
+    int read, tread;
+    unsigned char *send, *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;
+    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 l-sbeg;