Add CHECK_HEAP_ALIGN to perform runtime alignment checks

Adds a much cheaper CHECK_HEAP_ALIGN option to do heap access
alignment checks.  Less extensive than SAFE_HEAP, but also much
cheaper.

1 files changed, 19 insertions, 0 deletions

diff --git a/src/preamble.js b/src/preamble.js
index 6f4b49de..71b123e7 100644
--- a/src/preamble.js
+++ b/src/preamble.js
@@ -150,6 +150,25 @@ function SAFE_HEAP_COPY_HISTORY(dest, src) {
 //==========================================
 #endif
 
+#if CHECK_HEAP_ALIGN
+//========================================
+// Debugging tools - alignment check
+//========================================
+function CHECK_ALIGN_8(addr) {
+  assert((addr & 7) == 0, "address must be 8-byte aligned, is " + addr + "!");
+  return addr;
+}
+function CHECK_ALIGN_4(addr) {
+  assert((addr & 3) == 0, "address must be 4-byte aligned, is " + addr + "!");
+  return addr;
+}
+function CHECK_ALIGN_2(addr) {
+  assert((addr & 1) == 0, "address must be 2-byte aligned!");
+  return addr;
+}
+#endif
+
+
 #if CHECK_OVERFLOWS
 //========================================
 // Debugging tools - Mathop overflows