+int parse_extension(char *ext)
+{
+ int extension = -1;
+ char *ep;
+
+ if (ext == NULL)
+ return -1;
+
+ if ((ext[strlen(ext)-1] == 's') ||
+ (ext[strlen(ext)-1] == 'S')) {
+ double t;
+ double diff = 1;
+ uint8_t high = 0;
+ uint8_t low = 0;
+ uint8_t i;
+
+ t = strtoul(ext, &ep, 10);
+ if ((*ep != 's') && (*ep != 'S')) {
+ fprintf(stderr, "Not a valid time in seconds: %s\n", ext);
+ return -1;
+ }
+
+ /* time = 2^(high nibble) * (low nibble) * 0.25 , high may only be 12 */
+ t /= 0.25;
+#ifdef DEBUG
+ printf("t: %f\n", t);
+#endif
+
+ for(i = 1; i <= 0xf; i++) {
+ double h;
+ double l;
+ uint8_t i_l;
+ double d;
+
+#ifdef DEBUG
+ printf("i: 0x%01x\n", i);
+#endif
+
+ h = t / i;
+#ifdef DEBUG
+ printf("h: %f\n", h);
+#endif
+
+ l = log2(h);
+#ifdef DEBUG
+ printf("l: %f\n", l);
+#endif
+
+ i_l = l;
+ if (i_l > 12)
+ i_l = 12;
+
+ d = l - i_l;
+
+#ifdef DEBUG
+ printf("d: %f\n", d);
+#endif
+
+ if (d < diff) {
+#ifdef DEBUG
+ printf("Current best match!\n");
+#endif
+ diff = d;
+ high = l;
+ low = i;
+ }
+ }
+
+#ifdef DEBUG
+ printf("Got: %f, high: %01x, low: %01x\n", t, high, low);
+#endif
+
+ if ((high == 0) && (low == 0)) {
+ fprintf(stderr, "Can't find extension byte for %s!\n", ext);
+ return -1;
+ }
+
+ extension = ((high & 0xf) << 4) | (low & 0xf);
+ } else {
+ unsigned long val;
+
+ val = strtoul(ext, &ep, 16);
+ if (*ep != '\0') {
+ fprintf(stderr, "Not a 1 byte hexstring or time: %s\n", ext);
+ return -1;
+ }
+
+ extension = val & 0xff;
+ }
+
+ return extension;
+}
+