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Allow more fine-grained overclocking

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Some games can benefit from a little overclocking but start behaving
strangely at 2x.  Make the internal overclock ratio a fixed point
number and add 3 fractional settings.
This commit is contained in:
Brian Koropoff 2017-10-04 22:05:33 -07:00
parent 82d83c43ec
commit f3e0641b1b
9 changed files with 32 additions and 24 deletions
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3
Makefile.libretro
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@ -441,7 +441,8 @@ LIBRETRO_CFLAGS += $(BPP_DEFINES) \
$(PLATFORM_DEFINES) \
-D__LIBRETRO__ \
-DM68K_ALLOW_OVERCLOCK \
-DZ80_ALLOW_OVERCLOCK
-DZ80_ALLOW_OVERCLOCK \
-DCYCLE_SHIFT=10
ifneq (,$(findstring msvc,$(platform)))
LIBRETRO_CFLAGS += -DINLINE="static _inline"

2
core/m68k/m68k.h
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@ -269,7 +269,7 @@ typedef struct
uint address_space; /* Current FC code */
#ifdef M68K_ALLOW_OVERCLOCK
uint8 overclock_ratio;
int cycle_ratio;
#endif
/* Callbacks to host */

2
core/m68k/m68kcpu.c
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@ -320,7 +320,7 @@ void m68k_init(void)
#endif
#ifdef M68K_ALLOW_OVERCLOCK
m68k.overclock_ratio = 1;
m68k.cycle_ratio = 1 << CYCLE_SHIFT;
#endif
#if M68K_EMULATE_INT_ACK == OPT_ON

2
core/m68k/m68kcpu.h
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@ -515,7 +515,7 @@
/* ---------------------------- Cycle Counting ---------------------------- */
#ifdef M68K_ALLOW_OVERCLOCK
#define USE_CYCLES(A) m68ki_cpu.cycles += (A) / m68ki_cpu.overclock_ratio
#define USE_CYCLES(A) m68ki_cpu.cycles += ((A) * m68ki_cpu.cycle_ratio) >> CYCLE_SHIFT
#else
#define USE_CYCLES(A) m68ki_cpu.cycles += (A)
#endif

2
core/m68k/s68kcpu.c
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@ -285,7 +285,7 @@ void s68k_init(void)
#endif
#ifdef M68K_ALLOW_OVERCLOCK
s68k.overclock_ratio = 1;
s68k.cycle_ratio = 1 << CYCLE_SHIFT;
#endif
#if M68K_EMULATE_INT_ACK == OPT_ON

6
core/z80/z80.c
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@ -202,7 +202,7 @@
#define HALT Z80.halt
#ifdef Z80_ALLOW_OVERCLOCK
#define USE_CYCLES(A) Z80.cycles += (A) / z80_overclock_ratio
#define USE_CYCLES(A) Z80.cycles += ((A) * z80_cycle_ratio) >> CYCLE_SHIFT
#else
#define USE_CYCLES(A) Z80.cycles += (A)
#endif
@ -210,7 +210,7 @@
Z80_Regs Z80;
#ifdef Z80_ALLOW_OVERCLOCK
UINT8 z80_overclock_ratio;
UINT32 z80_cycle_ratio;
#endif
unsigned char *z80_readmap[64];
@ -3369,7 +3369,7 @@ void z80_init(const void *config, int (*irqcallback)(int))
Z80.daisy = config;
Z80.irq_callback = irqcallback;
#ifdef Z80_ALLOW_OVERCLOCK
z80_overclock_ratio = 1;
z80_cycle_ratio = 1 << CYCLE_SHIFT;
#endif
/* Clear registers values (NB: should be random on real hardware ?) */

2
core/z80/z80.h
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@ -52,7 +52,7 @@ typedef struct
extern Z80_Regs Z80;
#ifdef Z80_ALLOW_OVERCLOCK
extern UINT8 z80_overclock_ratio;
extern UINT32 z80_cycle_ratio;
#endif
extern unsigned char *z80_readmap[64];

35
libretro/libretro.c
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@ -1257,10 +1257,17 @@ static void check_variables(void)
var.key = "genesis_plus_gx_overclock";
environ_cb(RETRO_ENVIRONMENT_GET_VARIABLE, &var);
{
if (strcmp(var.value, "1x") == 0)
config.overclock = 0;
else if (strcmp(var.value, "2x") == 0)
config.overclock = 1;
/* Cycle ratios multiply cycle count, so use reciprocal */
if (strcmp(var.value, "100%") == 0)
config.overclock = (100 << CYCLE_SHIFT)/100;
else if (strcmp(var.value, "125%") == 0)
config.overclock = (100 << CYCLE_SHIFT)/125;
else if (strcmp(var.value, "150%") == 0)
config.overclock = (100 << CYCLE_SHIFT)/150;
else if (strcmp(var.value, "175%") == 0)
config.overclock = (100 << CYCLE_SHIFT)/175;
else if (strcmp(var.value, "200%") == 0)
config.overclock = (100 << CYCLE_SHIFT)/200;
}
#endif
@ -1709,7 +1716,7 @@ void retro_set_environment(retro_environment_t cb)
{ "genesis_plus_gx_gun_cursor", "Show Lightgun crosshair; disabled|enabled" },
{ "genesis_plus_gx_invert_mouse", "Invert Mouse Y-axis; disabled|enabled" },
#ifdef HAVE_OVERCLOCK
{ "genesis_plus_gx_overclock", "Overclock CPU; 1x|2x" },
{ "genesis_plus_gx_overclock", "CPU speed; 100%|125%|150%|175%|200%" },
#endif
{ NULL, NULL },
};
@ -2360,30 +2367,30 @@ void retro_run(void)
if (system_hw == SYSTEM_MCD)
{
#ifdef M68K_ALLOW_OVERCLOCK
if (config.overclock && overclock_delay == 0)
m68k.overclock_ratio = 2;
if (overclock_delay == 0)
m68k.cycle_ratio = config.overclock;
else
m68k.overclock_ratio = 1;
m68k.cycle_ratio = 1 << CYCLE_SHIFT;
#endif
system_frame_scd(0);
}
else if ((system_hw & SYSTEM_PBC) == SYSTEM_MD)
{
#ifdef M68K_ALLOW_OVERCLOCK
if (config.overclock && overclock_delay == 0)
m68k.overclock_ratio = 2;
if (overclock_delay == 0)
m68k.cycle_ratio = config.overclock;
else
m68k.overclock_ratio = 1;
m68k.cycle_ratio = 1 << CYCLE_SHIFT;
#endif
system_frame_gen(0);
}
else
{
#ifdef Z80_ALLOW_OVERCLOCK
if (config.overclock && overclock_delay == 0)
z80_overclock_ratio = 2;
if (overclock_delay == 0)
z80_cycle_ratio = config.overclock;
else
z80_overclock_ratio = 1;
z80_cycle_ratio = 1 << CYCLE_SHIFT;
#endif
system_frame_sms(0);
}

2
libretro/osd.h
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@ -120,7 +120,7 @@ struct
t_input_config input[MAX_INPUTS];
uint8 invert_mouse;
uint8 gun_cursor;
uint8 overclock;
uint32 overclock;
} config;
extern char GG_ROM[256];