From 1eb42b0dfd6209118c90774d8d1615b663abf960 Mon Sep 17 00:00:00 2001
From: Sam Lantinga <[EMAIL REDACTED]>
Date: Mon, 6 Oct 2025 20:48:43 -0700
Subject: [PATCH] Added SSE accelerated RGB565 to 32-bit pixel conversions
---
src/video/SDL_blit_N.c | 123 +++++++++++++++++++++++++++++++++++++++--
1 file changed, 118 insertions(+), 5 deletions(-)
diff --git a/src/video/SDL_blit_N.c b/src/video/SDL_blit_N.c
index e8f5b71e76fb6..8b9a6137e913f 100644
--- a/src/video/SDL_blit_N.c
+++ b/src/video/SDL_blit_N.c
@@ -38,7 +38,7 @@
// Functions to blit from N-bit surfaces to other surfaces
#define BLIT_FEATURE_NONE 0x00
-#define BLIT_FEATURE_HAS_MMX 0x01
+#define BLIT_FEATURE_HAS_SSE41 0x01
#define BLIT_FEATURE_HAS_ALTIVEC 0x02
#define BLIT_FEATURE_ALTIVEC_DONT_USE_PREFETCH 0x04
@@ -875,8 +875,8 @@ static Uint32 GetBlitFeatures(void)
static Uint32 features = ~0u;
if (features == ~0u) {
features = (0
- // Feature 1 is has-MMX
- | ((SDL_HasMMX()) ? BLIT_FEATURE_HAS_MMX : 0)
+ // Feature 1 is has-SSE41
+ | ((SDL_HasSSE41()) ? BLIT_FEATURE_HAS_SSE41 : 0)
// Feature 2 is has-AltiVec
| ((SDL_HasAltiVec()) ? BLIT_FEATURE_HAS_ALTIVEC : 0)
// Feature 4 is dont-use-prefetch
@@ -890,8 +890,8 @@ static Uint32 GetBlitFeatures(void)
#pragma altivec_model off
#endif
#else
-// Feature 1 is has-MMX
-#define GetBlitFeatures() ((SDL_HasMMX() ? BLIT_FEATURE_HAS_MMX : 0))
+// Feature 1 is has-SSE41
+#define GetBlitFeatures() ((SDL_HasSSE41() ? BLIT_FEATURE_HAS_SSE41 : 0))
#endif
// This is now endian dependent
@@ -1163,6 +1163,109 @@ static void Blit_XRGB8888_RGB565(SDL_BlitInfo *info)
#endif // USE_DUFFS_LOOP
}
+#ifdef SDL_SSE4_1_INTRINSICS
+
+static void SDL_TARGETING("sse4.1") Blit_RGB565_32_SSE41(SDL_BlitInfo *info, int Rshift, int Gshift, int Bshift, int Amask)
+{
+ int c;
+ int width, height;
+ const Uint16 *src;
+ Uint32 *dst;
+ int srcskip, dstskip;
+ Uint8 r, g, b;
+
+ // Set up some basic variables
+ width = info->dst_w;
+ height = info->dst_h;
+ src = (const Uint16 *)info->src;
+ srcskip = info->src_skip / 2;
+ dst = (Uint32 *)info->dst;
+ dstskip = info->dst_skip / 4;
+
+ while (height--) {
+ // Copy in 4 pixel chunks
+ for (c = width / 4; c; --c) {
+ // Load 4 16-bit RGB565 pixels into an SSE register
+ __m128i pixels_rgb565 = _mm_loadu_si128((__m128i*)src);
+
+ // Extract Red components (5 bits)
+ __m128i red_5bit = _mm_and_si128(pixels_rgb565, _mm_set1_epi16(0xF800)); // Mask for Red
+ red_5bit = _mm_srli_epi16(red_5bit, 11); // Shift to get 5-bit value
+ __m128i red_8bit = _mm_cvtepu16_epi32(red_5bit); // Convert to 32-bit and zero-extend
+ red_8bit = _mm_slli_epi32(red_8bit, 3); // Scale to 8 bits (multiply by 8)
+ red_8bit = _mm_or_si128(red_8bit, _mm_srli_epi32(red_8bit, 5)); // Replicate top 3 bits for better scaling
+
+ // Extract Green components (6 bits)
+ __m128i green_6bit = _mm_and_si128(pixels_rgb565, _mm_set1_epi16(0x07E0)); // Mask for Green
+ green_6bit = _mm_srli_epi16(green_6bit, 5); // Shift to get 6-bit value
+ __m128i green_8bit = _mm_cvtepu16_epi32(green_6bit); // Convert to 32-bit and zero-extend
+ green_8bit = _mm_slli_epi32(green_8bit, 2); // Scale to 8 bits (multiply by 4)
+ green_8bit = _mm_or_si128(green_8bit, _mm_srli_epi32(green_8bit, 6)); // Replicate top 2 bits
+
+ // Extract Blue components (5 bits)
+ __m128i blue_5bit = _mm_and_si128(pixels_rgb565, _mm_set1_epi16(0x001F)); // Mask for Blue
+ __m128i blue_8bit = _mm_cvtepu16_epi32(blue_5bit); // Convert to 32-bit and zero-extend
+ blue_8bit = _mm_slli_epi32(blue_8bit, 3); // Scale to 8 bits (multiply by 8)
+ blue_8bit = _mm_or_si128(blue_8bit, _mm_srli_epi32(blue_8bit, 5)); // Replicate top 3 bits
+
+ // Set Alpha to opaque (0xFF)
+ __m128i alpha_8bit = _mm_set1_epi32(Amask);
+
+ // Combine into 32-bit values
+ __m128i argb_pixels_low = _mm_or_si128(alpha_8bit, _mm_slli_epi32(red_8bit, Rshift));
+ argb_pixels_low = _mm_or_si128(argb_pixels_low, _mm_slli_epi32(green_8bit, Gshift));
+ argb_pixels_low = _mm_or_si128(argb_pixels_low, _mm_slli_epi32(blue_8bit, Bshift));
+
+ // Store the results
+ _mm_storeu_si128((__m128i*)dst, argb_pixels_low);
+ src += 4;
+ dst += 4;
+ }
+ // Get any leftovers
+ switch (width & 3) {
+ case 3:
+ RGB_FROM_RGB565(*src, r, g, b);
+ *dst++ = (r << Rshift) | (g << Gshift) | (b << Bshift) | Amask;
+ ++src;
+ SDL_FALLTHROUGH;
+ case 2:
+ RGB_FROM_RGB565(*src, r, g, b);
+ *dst++ = (r << Rshift) | (g << Gshift) | (b << Bshift) | Amask;
+ ++src;
+ SDL_FALLTHROUGH;
+ case 1:
+ RGB_FROM_RGB565(*src, r, g, b);
+ *dst++ = (r << Rshift) | (g << Gshift) | (b << Bshift) | Amask;
+ ++src;
+ break;
+ }
+ src += srcskip;
+ dst += dstskip;
+ }
+}
+
+static void Blit_RGB565_ARGB8888_SSE41(SDL_BlitInfo * info)
+{
+ Blit_RGB565_32_SSE41(info, 16, 8, 0, 0xFF000000);
+}
+
+static void Blit_RGB565_ABGR8888_SSE41(SDL_BlitInfo * info)
+{
+ Blit_RGB565_32_SSE41(info, 0, 8, 16, 0xFF000000);
+}
+
+static void Blit_RGB565_RGBA8888_SSE41(SDL_BlitInfo * info)
+{
+ Blit_RGB565_32_SSE41(info, 24, 16, 8, 0x000000FF);
+}
+
+static void Blit_RGB565_BGRA8888_SSE41(SDL_BlitInfo * info)
+{
+ Blit_RGB565_32_SSE41(info, 8, 16, 24, 0x000000FF);
+}
+
+#endif // SDL_SSE4_1_INTRINSICS
+
#ifdef SDL_HAVE_BLIT_N_RGB565
// Special optimized blit for RGB 5-6-5 --> 32-bit RGB surfaces
@@ -2700,6 +2803,16 @@ static const struct blit_table normal_blit_2[] = {
{ 0x00007C00, 0x000003E0, 0x0000001F, 4, 0x00000000, 0x00000000, 0x00000000,
BLIT_FEATURE_HAS_ALTIVEC, Blit_RGB555_32Altivec, NO_ALPHA | COPY_ALPHA | SET_ALPHA },
#endif
+#ifdef SDL_SSE4_1_INTRINSICS
+ { 0x0000F800, 0x000007E0, 0x0000001F, 4, 0x00FF0000, 0x0000FF00, 0x000000FF,
+ BLIT_FEATURE_HAS_SSE41, Blit_RGB565_ARGB8888_SSE41, NO_ALPHA | COPY_ALPHA | SET_ALPHA },
+ { 0x0000F800, 0x000007E0, 0x0000001F, 4, 0x000000FF, 0x0000FF00, 0x00FF0000,
+ BLIT_FEATURE_HAS_SSE41, Blit_RGB565_ABGR8888_SSE41, NO_ALPHA | COPY_ALPHA | SET_ALPHA },
+ { 0x0000F800, 0x000007E0, 0x0000001F, 4, 0xFF000000, 0x00FF0000, 0x0000FF00,
+ BLIT_FEATURE_HAS_SSE41, Blit_RGB565_RGBA8888_SSE41, NO_ALPHA | COPY_ALPHA | SET_ALPHA },
+ { 0x0000F800, 0x000007E0, 0x0000001F, 4, 0x0000FF00, 0x00FF0000, 0xFF000000,
+ BLIT_FEATURE_HAS_SSE41, Blit_RGB565_BGRA8888_SSE41, NO_ALPHA | COPY_ALPHA | SET_ALPHA },
+#endif
#ifdef SDL_HAVE_BLIT_N_RGB565
{ 0x0000F800, 0x000007E0, 0x0000001F, 4, 0x00FF0000, 0x0000FF00, 0x000000FF,
0, Blit_RGB565_ARGB8888, NO_ALPHA | COPY_ALPHA | SET_ALPHA },