From 8c7e44098a7ad2037e4cb0a331ae6463b9d5013f Mon Sep 17 00:00:00 2001
From: David Mak <chmakac@connect.ust.hk>
Date: Thu, 15 Feb 2024 14:57:41 +0800
Subject: [PATCH] core: Fix IRRT implementation of ndarray_flatten_index

---
 nac3core/src/codegen/irrt/irrt.c | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/nac3core/src/codegen/irrt/irrt.c b/nac3core/src/codegen/irrt/irrt.c
index 97969d1ef..778ad292e 100644
--- a/nac3core/src/codegen/irrt/irrt.c
+++ b/nac3core/src/codegen/irrt/irrt.c
@@ -278,12 +278,13 @@ uint32_t __nac3_ndarray_flatten_index(
 ) {
     uint32_t idx = 0;
     uint32_t stride = 1;
-    for (uint32_t i = num_dims - 1; i-- >= 0; ) {
-        if (i < num_indices) {
-            idx += (stride * indices[i]);
+    for (uint32_t i = 0; i < num_dims; ++i) {
+        uint32_t ri = num_dims - i - 1;
+        if (ri < num_indices) {
+            idx += (stride * indices[ri]);
         }
 
-        stride *= dims[i];
+        stride *= dims[ri];
     }
     return idx;
 }
@@ -296,12 +297,13 @@ uint64_t __nac3_ndarray_flatten_index64(
 ) {
     uint64_t idx = 0;
     uint64_t stride = 1;
-    for (uint64_t i = num_dims - 1; i-- >= 0; ) {
-        if (i < num_indices) {
-            idx += (stride * indices[i]);
+    for (uint64_t i = 0; i < num_dims; ++i) {
+        uint64_t ri = num_dims - i - 1;
+        if (ri < num_indices) {
+            idx += (stride * indices[ri]);
         }
 
-        stride *= dims[i];
+        stride *= dims[ri];
     }
     return idx;
 }