From 66f7babe86983abbf6006f1ba5175956413f9123 Mon Sep 17 00:00:00 2001
From: Lior Halphon <LIJI32@gmail.com>
Date: Sun, 26 Dec 2021 15:50:24 +0200
Subject: [PATCH] Cache the clock rate

---
 Core/gb.c         | 29 ++++++++++++++++++++---------
 Core/gb.h         |  3 +++
 Core/save_state.c |  1 +
 3 files changed, 24 insertions(+), 9 deletions(-)

diff --git a/Core/gb.c b/Core/gb.c
index a98b08f..bb08cf5 100644
--- a/Core/gb.c
+++ b/Core/gb.c
@@ -1591,6 +1591,7 @@ void GB_reset(GB_gameboy_t *gb)
 {
     uint32_t mbc_ram_size = gb->mbc_ram_size;
     GB_model_t model = gb->model;
+    GB_update_clock_rate(gb);
     uint8_t rtc_section[GB_SECTION_SIZE(rtc)];
     memcpy(rtc_section, GB_GET_SECTION(gb, rtc), sizeof(rtc_section));
     memset(gb, 0, (size_t)GB_GET_SECTION((GB_gameboy_t *) 0, unsaved));
@@ -1756,24 +1757,34 @@ GB_registers_t *GB_get_registers(GB_gameboy_t *gb)
 void GB_set_clock_multiplier(GB_gameboy_t *gb, double multiplier)
 {
     gb->clock_multiplier = multiplier;
+    GB_update_clock_rate(gb);
 }
 
 uint32_t GB_get_clock_rate(GB_gameboy_t *gb)
 {
-    return GB_get_unmultiplied_clock_rate(gb) * gb->clock_multiplier;
+    return gb->clock_rate;
 }
 
-
 uint32_t GB_get_unmultiplied_clock_rate(GB_gameboy_t *gb)
 {
-    if (gb->model & GB_MODEL_PAL_BIT) {
-        return SGB_PAL_FREQUENCY;
-    }
-    if ((gb->model & ~GB_MODEL_NO_SFC_BIT) == GB_MODEL_SGB) {
-        return SGB_NTSC_FREQUENCY;
-    }
-    return CPU_FREQUENCY;
+    return gb->unmultiplied_clock_rate;
 }
+
+void GB_update_clock_rate(GB_gameboy_t *gb)
+{
+    if (gb->model & GB_MODEL_PAL_BIT) {
+        gb->unmultiplied_clock_rate = SGB_PAL_FREQUENCY;
+    }
+    else if ((gb->model & ~GB_MODEL_NO_SFC_BIT) == GB_MODEL_SGB) {
+        gb->unmultiplied_clock_rate = SGB_NTSC_FREQUENCY;
+    }
+    else {
+        gb->unmultiplied_clock_rate = CPU_FREQUENCY;
+    }
+    
+    gb->clock_rate = gb->unmultiplied_clock_rate * gb->clock_multiplier;
+}
+
 void GB_set_border_mode(GB_gameboy_t *gb, GB_border_mode_t border_mode)
 {
     if (gb->border_mode > GB_BORDER_ALWAYS) return;
diff --git a/Core/gb.h b/Core/gb.h
index 54fa0f3..de1b4aa 100644
--- a/Core/gb.h
+++ b/Core/gb.h
@@ -667,6 +667,8 @@ struct GB_gameboy_internal_s {
         uint64_t cycles_since_last_sync; // In 8MHz units
         GB_rtc_mode_t rtc_mode;
         uint32_t rtc_second_length;
+        uint32_t clock_rate;
+        uint32_t unmultiplied_clock_rate;
 
         /* Audio */
         GB_apu_output_t apu_output;
@@ -918,6 +920,7 @@ uint32_t GB_get_rom_crc32(GB_gameboy_t *gb);
 
 #ifdef GB_INTERNAL
 internal void GB_borrow_sgb_border(GB_gameboy_t *gb);
+internal void GB_update_clock_rate(GB_gameboy_t *gb);
 #endif
     
 #endif /* GB_h */
diff --git a/Core/save_state.c b/Core/save_state.c
index 4dc304e..d5297b5 100644
--- a/Core/save_state.c
+++ b/Core/save_state.c
@@ -383,6 +383,7 @@ static void sanitize_state(GB_gameboy_t *gb)
         }
         gb->sgb->current_player &= gb->sgb->player_count - 1;
     }
+    GB_update_clock_rate(gb);
 }
 
 static bool dump_section(virtual_file_t *file, const void *src, uint32_t size)