From d1fcff0a08a70bc5f180303a2e3f62d998bf2c65 Mon Sep 17 00:00:00 2001
From: rakslice <rakslice@gmail.com>
Date: Tue, 18 Aug 2020 03:28:43 -0700
Subject: [PATCH] corresponding gamma change for sdl1

---
 BasiliskII/src/SDL/video_sdl.cpp | 36 ++++++++++++++++++++++++++++++--
 1 file changed, 34 insertions(+), 2 deletions(-)

diff --git a/BasiliskII/src/SDL/video_sdl.cpp b/BasiliskII/src/SDL/video_sdl.cpp
index d7a46479..d3e764bb 100644
--- a/BasiliskII/src/SDL/video_sdl.cpp
+++ b/BasiliskII/src/SDL/video_sdl.cpp
@@ -155,6 +155,11 @@ static SDL_mutex *frame_buffer_lock = NULL;
 #define LOCK_FRAME_BUFFER SDL_LockMutex(frame_buffer_lock)
 #define UNLOCK_FRAME_BUFFER SDL_UnlockMutex(frame_buffer_lock)
 
+// Previously set gamma tables
+static uint16 last_gamma_red[256];
+static uint16 last_gamma_green[256];
+static uint16 last_gamma_blue[256];
+
 // Video refresh function
 static void VideoRefreshInit(void);
 static void (*video_refresh)(void);
@@ -1363,9 +1368,36 @@ void SDL_monitor_desc::set_palette(uint8 *pal, int num_in)
 {
 	const VIDEO_MODE &mode = get_current_mode();
 
-	// FIXME: how can we handle the gamma ramp?
-	if ((int)VIDEO_MODE_DEPTH > VIDEO_DEPTH_8BIT)
+	if ((int)VIDEO_MODE_DEPTH > VIDEO_DEPTH_8BIT) {
+		// handle the gamma ramp
+		uint16 red[256];
+		uint16 green[256];
+		uint16 blue[256];
+		
+		for (int i = 0; i < 256; i++) {
+			red[i] = pal[i*3 + 0] << 8;
+			green[i] = pal[i*3 + 1] << 8;
+			blue[i] = pal[i*3 + 2] << 8;
+		}
+		
+		bool changed = (memcmp(red, last_gamma_red, 512) != 0 ||
+		                memcmp(green, last_gamma_green, 512) != 0 ||
+						memcmp(blue, last_gamma_blue, 512) != 0);
+		
+		if (changed) {
+			int result = SDL_SetGammaRamp(red, green, blue);
+
+			if (result < 0) {
+				printf("SDL_SetGammaRamp returned %d, SDL error:", result, SDL_GetError());
+			}
+			
+			memcpy(last_gamma_red, red, 512);
+			memcpy(last_gamma_green, green, 512);
+			memcpy(last_gamma_blue, blue, 512);
+		}
+
 		return;
+	}
 
 	LOCK_PALETTE;