From 389ed7111e934452a7ed76c3df0b16c32c783f45 Mon Sep 17 00:00:00 2001
From: Themaister <maister@archlinux.us>
Date: Thu, 19 Aug 2010 15:21:30 +0200
Subject: [PATCH] Added grayscale filter.

---
 hqflt/grayscale.c | 21 +++++++++++++++++++++
 hqflt/grayscale.h |  7 +++++++
 ssnes.c           |  7 +++++++
 3 files changed, 35 insertions(+)
 create mode 100644 hqflt/grayscale.c
 create mode 100644 hqflt/grayscale.h

diff --git a/hqflt/grayscale.c b/hqflt/grayscale.c
new file mode 100644
index 0000000000..dd2d5081ea
--- /dev/null
+++ b/hqflt/grayscale.c
@@ -0,0 +1,21 @@
+/* Very simple grayscale filter.
+ * Author: Hans-Kristian Arntzen
+ * License: Public domain
+ */
+
+#include "grayscale.h"
+
+// Input format 0RRRRRGGGGGBBBBB. Colors themselves could be switched around.
+void grayscale_filter(uint16_t *data, int width, int height)
+{
+   for (int i = 0; i < width * height; i++ )
+   {
+      int r, g, b, color;
+      r = (data[i] >> 10) & 0x1F;
+      g = (data[i] >> 5)  & 0x1F;
+      b = (data[i] >> 0)  & 0x1F;
+
+      color = (int)(r * 0.3 + g * 0.59 + b * 0.11);
+      data[i] = (color << 10) | (color << 5) | color;
+   }
+}
diff --git a/hqflt/grayscale.h b/hqflt/grayscale.h
new file mode 100644
index 0000000000..7333095112
--- /dev/null
+++ b/hqflt/grayscale.h
@@ -0,0 +1,7 @@
+/* Very simple grayscale filter.
+ * Author: Hans-Kristian Arntzen
+ * License: Public domain
+ */
+
+#include <stdint.h>
+void grayscale_filter(uint16_t *data, int width, int height);
diff --git a/ssnes.c b/ssnes.c
index d0d46cc2eb..e4dcfdf874 100644
--- a/ssnes.c
+++ b/ssnes.c
@@ -26,6 +26,7 @@
 #include "config.h"
 #include "driver.h"
 #include "hqflt/pastlib.h"
+#include "hqflt/grayscale.h"
 
 static bool video_active = true;
 static bool audio_active = true;
@@ -136,6 +137,8 @@ static void init_video_input(void)
    scale = 2;
 #elif VIDEO_FILTER == FILTER_HQ4X
    scale = 4;
+#elif VIDEO_FILTER == FILTER_GRAYSCALE
+   scale = 1;
 #else
    scale = 1;
 #endif
@@ -216,6 +219,10 @@ static void video_frame(const uint16_t *data, unsigned width, unsigned height)
    ProcessHQ4x(output, outputHQ4x);
    if ( !driver.video->frame(driver.video_data, outputHQ4x, width * 4, height * 4) )
       video_active = false;
+#elif VIDEO_FILTER == FILTER_GRAYSCALE
+   grayscale_filter(output, width, height);
+   if ( !driver.video->frame(driver.video_data, output, width, height) )
+      video_active = false;
 #else
    if ( !driver.video->frame(driver.video_data, output, width, height) )
       video_active = false;