feat: add signed leb128 decoding

main.cpp

@@ -87,6 +87,25 @@ inline int decode_leb128(uint8_t *src, uint64_t *dest)
     // return the number of bytes that we should move the src pointer
     return shift / 8 + (shift % 8 != 0);
 }
+// TODO: Deal with cases where size of LEB128 > word size
+inline int decode_sleb128(uint8_t *src, int64_t *dest)
+{
+    *dest = 0;
+    int shift = 0;
+    uint8_t val;
+    do {
+      val = *src++;
+      *dest |= (val & 0x7f) << shift;
+      shift += 7;
+    } while (val & 0x80);
+
+    // deal with signedness
+    if ((shift < 64) && (val & 0x40))
+      for (int i = 63; i < shift; ++i)
+        *dest |= (1 << shift); // sign extend
+    // return the number of bytes that we should move the src pointer
+    return shift / 8 + (shift % 8 != 0);
+}
 
 // globals
 uint64_t cu_header_offset = 0;