jmode.c: zrle-pack, zrle-unpack

jmode.c

@@ -182,6 +182,28 @@ static bool zrle_consider(u8 * restrict in, sz n) {
   return savings > 0;
 }
 
+static sz zrle_pack(u8 * restrict in, sz n, u8 * restrict out) {
+  sz j = 0;
+  Fi(n, if (!in[i]) {
+    sz k = i + 1;
+    while (k < n && in[k] == 0) k++;
+    out[j++] = 0;
+    out[j++] = k - i - 1;
+    i = k - 1;
+  } else out[j++] = in[i]);
+  return j;
+}
+
+static sz zrle_unpack(u8 * restrict in, sz n, u8 * restrict out, sz outmax) {
+  sz j = 0;
+  Fi(n, if (!in[i]) {
+    if (j + in[i + 1] >= outmax) return 0;
+    memset(out + j, 0, in[i + 1]);
+    j += in[i + 1];  i++;
+  } else out[j++] = in[i]);
+  return j;
+}
+
 // ============================================================================
 //  Processing. We apply a few strategies that depend on some specifics of the
 //  process at hand: