From 6372dc688466efec867dcfe2186d668fda4efe0b Mon Sep 17 00:00:00 2001
From: FunkyFr3sh <cc.red.alert.1@googlemail.com>
Date: Tue, 20 Sep 2022 02:27:01 +0200
Subject: [PATCH] add AVX memset

---
 inc/blt.h       |  1 +
 src/blt.c       | 44 +++++++++++++++++++++++++++++---------------
 src/ddsurface.c |  2 +-
 3 files changed, 31 insertions(+), 16 deletions(-)

diff --git a/inc/blt.h b/inc/blt.h
index 1cd2a3f..76f3bf5 100644
--- a/inc/blt.h
+++ b/inc/blt.h
@@ -74,6 +74,7 @@ void blt_colorkey_mirror_stretch(
 
 void blt_clear(
     unsigned char* dst, 
+    char color,
     size_t size);
 
 void blt_colorfill(
diff --git a/src/blt.c b/src/blt.c
index 59549c9..028329a 100644
--- a/src/blt.c
+++ b/src/blt.c
@@ -461,16 +461,39 @@ void blt_colorkey_mirror_stretch(
 }
 
 void blt_clear(
-    unsigned char* dst, 
+    unsigned char* dst,
+    char color,
     size_t size)
 {
-    if (size >= 1024 * 200)
+#ifdef _MSC_VER
+    if (size < 1024 * 100 && g_blt_use_avx && !((DWORD)dst % 32))
     {
-        __stosb(dst, 0, size);
+        while (size >= 128)
+        {
+            __m256i c0 = _mm256_set1_epi8(color);
+
+            _mm256_store_si256((((__m256i*)dst) + 0), c0);
+            _mm256_store_si256((((__m256i*)dst) + 1), c0);
+            _mm256_store_si256((((__m256i*)dst) + 2), c0);
+            _mm256_store_si256((((__m256i*)dst) + 3), c0);
+
+            dst += 128;
+            size -= 128;
+        }
+
+        _mm256_zeroupper();
+
+        /* memset below handles the remainder */
+    }
+#endif
+
+    if (size >= 1024 * 100)
+    {
+        __stosb(dst, color, size);
     }
     else
     {
-        memset(dst, 0, size);
+        memset(dst, color, size);
     }
 }
 
@@ -500,22 +523,13 @@ void blt_colorfill(
     {
         if (size == dst_p)
         {
-            size_t s = dst_p * dst_h;
-
-            if (s >= 1024 * 200)
-            {
-                __stosb(dst, color, s);
-            }
-            else
-            {
-                memset(dst, color, s);
-            }
+            blt_clear(dst, color, dst_p * dst_h);
         }
         else
         {
             for (int i = 0; i < dst_h; i++)
             {
-                memset(dst, color, size);
+                blt_clear(dst, color, size);
                 dst += dst_p;
             }
         }
diff --git a/src/ddsurface.c b/src/ddsurface.c
index 913e5d0..7fdbf26 100644
--- a/src/ddsurface.c
+++ b/src/ddsurface.c
@@ -551,7 +551,7 @@ HRESULT dds_Flip(IDirectDrawSurfaceImpl* This, IDirectDrawSurfaceImpl* lpDDSurfa
 
         if (g_ddraw->flipclear)
         {
-            blt_clear(buf, backbuffer->size);
+            blt_clear(buf, 0, backbuffer->size);
         }
 
         LeaveCriticalSection(&g_ddraw->cs);