From 5a20ff0dc7c6a2fcde0b1e382f3d5a92aefa4ab9 Mon Sep 17 00:00:00 2001
From: Tatsuya79
Date: Thu, 8 Feb 2018 12:23:53 +0100
Subject: Overclock by reducing cycles.

---
 libretro.c      | 13 +++++++++++++
 source/snes9x.h |  8 +++++---
 2 files changed, 18 insertions(+), 3 deletions(-)

diff --git a/libretro.c b/libretro.c
index 0114559..42e316d 100644
--- a/libretro.c
+++ b/libretro.c
@@ -36,6 +36,7 @@ struct retro_perf_callback perf_cb;
 
 char retro_save_directory[PATH_MAX];
 char retro_base_name[PATH_MAX];
+bool overclock_cycles = false;
 
 #ifdef _WIN32
    char slash = '\\';
@@ -294,6 +295,7 @@ void retro_init(void)
    static const struct retro_variable vars[] =
    {
       { "catsfc_VideoMode", "Video Mode; auto|NTSC|PAL" },
+      { "catsfc_overclock_cycles", "CPU Overclock (Hack, Unsafe, Restart); disabled|enabled" },
       { NULL, NULL },
    };
 
@@ -378,6 +380,17 @@ static void check_variables(void)
       Settings.ForceNTSC = !strcmp(var.value, "NTSC");
       Settings.ForcePAL  = !strcmp(var.value, "PAL");
    }
+
+   var.key = "catsfc_overclock_cycles";
+   var.value = NULL;
+
+   if (environ_cb(RETRO_ENVIRONMENT_GET_VARIABLE, &var) && var.value)
+      {
+        if (strcmp(var.value, "enabled") == 0)
+          overclock_cycles = true;
+        else
+          overclock_cycles = false;
+      }
 }
 
 #ifdef PSP
diff --git a/source/snes9x.h b/source/snes9x.h
index 9e7d91d..4a4364c 100644
--- a/source/snes9x.h
+++ b/source/snes9x.h
@@ -46,9 +46,9 @@
 
 #define SNES_CYCLES_PER_SCANLINE ((uint32_t) ((SNES_SCANLINE_TIME / SNES_CLOCK_LEN) * 6 + 0.5))
 
-#define ONE_CYCLE      6u
-#define SLOW_ONE_CYCLE 8u
-#define TWO_CYCLES     12u
+#define ONE_CYCLE      (overclock_cycles ? 4u : 6u)
+#define SLOW_ONE_CYCLE (overclock_cycles ? 4u : 8u)
+#define TWO_CYCLES     (overclock_cycles ? 6u : 12u)
 
 #define SNES_TR_MASK     (1u << 4)
 #define SNES_TL_MASK     (1u << 5)
@@ -63,6 +63,8 @@
 #define SNES_Y_MASK      (1u << 14)
 #define SNES_B_MASK      (1u << 15)
 
+extern bool overclock_cycles;
+
 enum
 {
    SNES_MULTIPLAYER5,
-- 
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