From f2363c23915aeab1900842f815ccfcf5f67f8210 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Ekl=C3=B6f?= <daniel@ekloef.se>
Date: Sun, 7 Jul 2019 17:10:30 +0200
Subject: [PATCH] grid: add a fast path to grid_memmove()

Recognize the case where both the destination and source can be fully
accessed, and to a plain memmove() in this case.
---
 grid.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/grid.c b/grid.c
index a09e3d21..c08a002e 100644
--- a/grid.c
+++ b/grid.c
@@ -47,6 +47,19 @@ grid_memclear(struct grid *grid, int start, int length)
 void
 grid_memmove(struct grid *grid, int dst, int src, int length)
 {
+    /* Fast path, we can move everything in one swoop */
+    {
+        int count = length;
+        struct cell *dst_cells = grid_get_range(grid, dst, &count);
+        if (count == length) {
+            struct cell *src_cells = grid_get_range(grid, src, &count);
+            if (count == length) {
+                memmove(dst_cells, src_cells, length * sizeof(dst_cells[0]));
+                return;
+            }
+        }
+    }
+
     int left = length;
     int copy_idx = 0;
     struct cell copy[left];