start work on new interpreter

next/core/sleb128.c

@@ -0,0 +1,45 @@
+//
+// Created by lobo on 2/5/26.
+//
+
+#include "sleb128.h"
+
+intptr_t growl_sleb128_decode(uint8_t **ptr) {
+  intptr_t result = 0;
+  intptr_t shift = 0;
+  uint8_t byte;
+
+  do {
+    byte = **ptr;
+    (*ptr)++;
+    result |= (intptr_t)(byte & 0x7F) << shift;
+    shift += 7;
+  } while (byte & 0x80);
+
+  if ((shift < 64) && (byte & 0x40)) {
+    result |= -(1LL << shift);
+  }
+
+  return result;
+}
+
+size_t growl_sleb128_peek(const uint8_t *ptr, intptr_t *out) {
+  intptr_t result = 0, shift = 0;
+  size_t bytes = 0;
+  uint8_t byte;
+
+  do {
+    byte = ptr[bytes];
+    bytes++;
+    result |= (intptr_t)(byte & 0x7f) << shift;
+    shift += 7;
+  } while (byte & 0x80);
+
+  if (shift < 64 && byte & 0x40) {
+    result |= -(1LL << shift);
+  }
+
+  if (out)
+    *out = result;
+  return bytes;
+}