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peanut_gb.h
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/**
* MIT License
*
* Copyright (c) 2018-2023 Mahyar Koshkouei
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to
* deal in the Software without restriction, including without limitation the
* rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
* sell copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
* IN THE SOFTWARE.
*
* Please note that at least two parts of source code within this project was
* taken from the SameBoy project at https://github.com/LIJI32/SameBoy/ which at
* the time of this writing is released under the MIT License. Occurrences of
* this code is marked as being taken from SameBoy with a comment.
* SameBoy, and code marked as being taken from SameBoy,
* is Copyright (c) 2015-2019 Lior Halphon.
*/
#ifndef PEANUT_GB_H
#define PEANUT_GB_H
#if defined(__has_include)
# if __has_include("version.all")
# include "version.all" /* Version information */
# endif
#else
/* Stub __has_include for later. */
# define __has_include(x) 0
#endif
#include <stdlib.h> /* Required for qsort and abort */
#include <stdbool.h> /* Required for bool types */
#include <stdint.h> /* Required for int types */
#include <string.h> /* Required for memset */
#include <time.h> /* Required for tm struct */
/**
* If PEANUT_GB_IS_LITTLE_ENDIAN is positive, then Peanut-GB will be configured
* for a little endian platform. If 0, then big endian.
*/
#if !defined(PEANUT_GB_IS_LITTLE_ENDIAN)
/* If endian is not defined, then attempt to detect it. */
# if defined(__BYTE_ORDER__)
# if __BYTE_ORDER__ != __ORDER_LITTLE_ENDIAN__
/* Building for a big endian platform. */
# define PEANUT_GB_IS_LITTLE_ENDIAN 0
# else
# define PEANUT_GB_IS_LITTLE_ENDIAN 1
# endif /* __BYTE_ORDER__ != __ORDER_LITTLE_ENDIAN__ */
# elif defined(_WIN32)
/* We assume that Windows is always little endian by default. */
# define PEANUT_GB_IS_LITTLE_ENDIAN 1
# elif !defined(PEANUT_GB_IS_LITTLE_ENDIAN)
# error "Could not detect target platform endian. Please define PEANUT_GB_IS_LITTLE_ENDIAN"
# endif
#endif /* !defined(PEANUT_GB_IS_LITTLE_ENDIAN) */
#if PEANUT_GB_IS_LITTLE_ENDIAN == 0
# error "Peanut-GB only supports little endian targets"
/* This is because the logic has been written with assumption of little
* endian byte order. */
#endif
/** Definitions for compile-time setting of features. **/
/**
* Sound support must be provided by an external library. When audio_read() and
* audio_write() functions are provided, define ENABLE_SOUND to a non-zero value
* before including peanut_gb.h in order for these functions to be used.
*/
#ifndef ENABLE_SOUND
# define ENABLE_SOUND 1
#endif
/* Enable LCD drawing. On by default. May be turned off for testing purposes. */
#ifndef ENABLE_LCD
# define ENABLE_LCD 1
#endif
/* Enable 16 bit colour palette. If disabled, only four colour shades are set in
* pixel data. */
#ifndef PEANUT_GB_12_COLOUR
# define PEANUT_GB_12_COLOUR 1
#endif
/* Adds more code to improve LCD rendering accuracy. */
#ifndef PEANUT_GB_HIGH_LCD_ACCURACY
# define PEANUT_GB_HIGH_LCD_ACCURACY 1
#endif
/* Use intrinsic functions. This may produce smaller and faster code. */
#ifndef PEANUT_GB_USE_INTRINSICS
# define PEANUT_GB_USE_INTRINSICS 1
#endif
/* Only include function prototypes. At least one file must *not* have this
* defined. */
// #define PEANUT_GB_HEADER_ONLY
/** Internal source code. **/
/* Interrupt masks */
#define VBLANK_INTR 0x01
#define LCDC_INTR 0x02
#define TIMER_INTR 0x04
#define SERIAL_INTR 0x08
#define CONTROL_INTR 0x10
#define ANY_INTR 0x1F
/* Memory section sizes for DMG */
#define WRAM_SIZE 0x2000
#define VRAM_SIZE 0x2000
#define HRAM_IO_SIZE 0x0100
#define OAM_SIZE 0x00A0
/* Memory addresses */
#define ROM_0_ADDR 0x0000
#define ROM_N_ADDR 0x4000
#define VRAM_ADDR 0x8000
#define CART_RAM_ADDR 0xA000
#define WRAM_0_ADDR 0xC000
#define WRAM_1_ADDR 0xD000
#define ECHO_ADDR 0xE000
#define OAM_ADDR 0xFE00
#define UNUSED_ADDR 0xFEA0
#define IO_ADDR 0xFF00
#define HRAM_ADDR 0xFF80
#define INTR_EN_ADDR 0xFFFF
/* Cart section sizes */
#define ROM_BANK_SIZE 0x4000
#define WRAM_BANK_SIZE 0x1000
#define CRAM_BANK_SIZE 0x2000
#define VRAM_BANK_SIZE 0x2000
/* DIV Register is incremented at rate of 16384Hz.
* 4194304 / 16384 = 256 clock cycles for one increment. */
#define DIV_CYCLES 256
/* Serial clock locked to 8192Hz on DMG.
* 4194304 / (8192 / 8) = 4096 clock cycles for sending 1 byte. */
#define SERIAL_CYCLES 4096
/* Calculating VSYNC. */
#define DMG_CLOCK_FREQ 4194304.0
#define SCREEN_REFRESH_CYCLES 70224.0
#define VERTICAL_SYNC (DMG_CLOCK_FREQ/SCREEN_REFRESH_CYCLES)
/* Real Time Clock is locked to 1Hz. */
#define RTC_CYCLES ((uint_fast32_t)DMG_CLOCK_FREQ)
/* SERIAL SC register masks. */
#define SERIAL_SC_TX_START 0x80
#define SERIAL_SC_CLOCK_SRC 0x01
/* STAT register masks */
#define STAT_LYC_INTR 0x40
#define STAT_MODE_2_INTR 0x20
#define STAT_MODE_1_INTR 0x10
#define STAT_MODE_0_INTR 0x08
#define STAT_LYC_COINC 0x04
#define STAT_MODE 0x03
#define STAT_USER_BITS 0xF8
/* LCDC control masks */
#define LCDC_ENABLE 0x80
#define LCDC_WINDOW_MAP 0x40
#define LCDC_WINDOW_ENABLE 0x20
#define LCDC_TILE_SELECT 0x10
#define LCDC_BG_MAP 0x08
#define LCDC_OBJ_SIZE 0x04
#define LCDC_OBJ_ENABLE 0x02
#define LCDC_BG_ENABLE 0x01
/** LCD characteristics **/
/* PPU cycles through modes every 456 cycles. */
#define LCD_LINE_CYCLES 456
/* Mode 0 starts on cycle 372. */
#define LCD_MODE_0_CYCLES 372
/* Mode 2 starts on cycle 204. */
#define LCD_MODE_2_CYCLES 204
/* Mode 3 starts on cycle 284. */
#define LCD_MODE_3_CYCLES 284
/* There are 154 scanlines. LY < 154. */
#define LCD_VERT_LINES 154
#define LCD_WIDTH 160
#define LCD_HEIGHT 144
/* VRAM Locations */
#define VRAM_TILES_1 (0x8000 - VRAM_ADDR)
#define VRAM_TILES_2 (0x8800 - VRAM_ADDR)
#define VRAM_BMAP_1 (0x9800 - VRAM_ADDR)
#define VRAM_BMAP_2 (0x9C00 - VRAM_ADDR)
#define VRAM_TILES_3 (0x8000 - VRAM_ADDR + VRAM_BANK_SIZE)
#define VRAM_TILES_4 (0x8800 - VRAM_ADDR + VRAM_BANK_SIZE)
/* Interrupt jump addresses */
#define VBLANK_INTR_ADDR 0x0040
#define LCDC_INTR_ADDR 0x0048
#define TIMER_INTR_ADDR 0x0050
#define SERIAL_INTR_ADDR 0x0058
#define CONTROL_INTR_ADDR 0x0060
/* SPRITE controls */
#define NUM_SPRITES 0x28
#define MAX_SPRITES_LINE 0x0A
#define OBJ_PRIORITY 0x80
#define OBJ_FLIP_Y 0x40
#define OBJ_FLIP_X 0x20
#define OBJ_PALETTE 0x10
/* Joypad buttons */
#define JOYPAD_A 0x01
#define JOYPAD_B 0x02
#define JOYPAD_SELECT 0x04
#define JOYPAD_START 0x08
#define JOYPAD_RIGHT 0x10
#define JOYPAD_LEFT 0x20
#define JOYPAD_UP 0x40
#define JOYPAD_DOWN 0x80
#define ROM_HEADER_CHECKSUM_LOC 0x014D
/* Local macros. */
#ifndef MIN
# define MIN(a, b) ((a) < (b) ? (a) : (b))
#endif
#define PEANUT_GB_ARRAYSIZE(array) (sizeof(array)/sizeof(array[0]))
#if !defined(__has_builtin)
/* Stub __has_builtin if it isn't available. */
# define __has_builtin(x) 0
#endif
/* The PGB_UNREACHABLE() macro tells the compiler that the code path will never
* be reached, allowing for further optimisation. */
#if !defined(PGB_UNREACHABLE)
# if __has_builtin(__builtin_unreachable)
# define PGB_UNREACHABLE() __builtin_unreachable()
# elif defined(_MSC_VER) && _MSC_VER >= 1200
# /* __assume is not available before VC6. */
# define PGB_UNREACHABLE() __assume(0)
# else
# define PGB_UNREACHABLE() abort()
# endif
#endif /* !defined(PGB_UNREACHABLE) */
#if !defined(PGB_UNLIKELY)
# if __has_builtin(__builtin_expect)
# define PGB_UNLIKELY(expr) __builtin_expect(!!(expr), 0)
# else
# define PGB_UNLIKELY(expr) (expr)
# endif
#endif /* !defined(PGB_UNLIKELY) */
#if !defined(PGB_LIKELY)
# if __has_builtin(__builtin_expect)
# define PGB_LIKELY(expr) __builtin_expect(!!(expr), 1)
# else
# define PGB_LIKELY(expr) (expr)
# endif
#endif /* !defined(PGB_LIKELY) */
#if PEANUT_GB_USE_INTRINSICS
/* If using MSVC, only enable intrinsics for x86 platforms*/
# if defined(_MSC_VER) && __has_include("intrin.h") && \
(defined(_M_IX86_FP) || defined(_M_AMD64) || defined(_M_X64))
/* Define intrinsic functions for MSVC. */
# include <intrin.h>
# define PGB_INTRIN_SBC(x,y,cin,res) _subborrow_u8(cin,x,y,&res)
# define PGB_INTRIN_ADC(x,y,cin,res) _addcarry_u8(cin,x,y,&res)
# endif /* MSVC */
/* Check for intrinsic functions in GCC and Clang. */
# if __has_builtin(__builtin_sub_overflow)
# define PGB_INTRIN_SBC(x,y,cin,res) __builtin_sub_overflow(x,y+cin,&res)
# define PGB_INTRIN_ADC(x,y,cin,res) __builtin_add_overflow(x,y+cin,&res)
# endif
#endif /* PEANUT_GB_USE_INTRINSICS */
#if defined(PGB_INTRIN_SBC)
# define PGB_INSTR_SBC_R8(r,cin) \
{ \
uint8_t temp; \
gb->cpu_reg.f.f_bits.c = PGB_INTRIN_SBC(gb->cpu_reg.a,r,cin,temp);\
gb->cpu_reg.f.f_bits.h = ((gb->cpu_reg.a ^ r ^ temp) & 0x10) > 0;\
gb->cpu_reg.f.f_bits.n = 1; \
gb->cpu_reg.f.f_bits.z = (temp == 0x00); \
gb->cpu_reg.a = temp; \
}
# define PGB_INSTR_CP_R8(r) \
{ \
uint8_t temp; \
gb->cpu_reg.f.f_bits.c = PGB_INTRIN_SBC(gb->cpu_reg.a,r,0,temp);\
gb->cpu_reg.f.f_bits.h = ((gb->cpu_reg.a ^ r ^ temp) & 0x10) > 0;\
gb->cpu_reg.f.f_bits.n = 1; \
gb->cpu_reg.f.f_bits.z = (temp == 0x00); \
}
#else
# define PGB_INSTR_SBC_R8(r,cin) \
{ \
uint16_t temp = gb->cpu_reg.a - (r + cin); \
gb->cpu_reg.f.f_bits.c = (temp & 0xFF00) ? 1 : 0; \
gb->cpu_reg.f.f_bits.h = ((gb->cpu_reg.a ^ r ^ temp) & 0x10) > 0; \
gb->cpu_reg.f.f_bits.n = 1; \
gb->cpu_reg.f.f_bits.z = ((temp & 0xFF) == 0x00); \
gb->cpu_reg.a = (temp & 0xFF); \
}
# define PGB_INSTR_CP_R8(r) \
{ \
uint16_t temp = gb->cpu_reg.a - r; \
gb->cpu_reg.f.f_bits.c = (temp & 0xFF00) ? 1 : 0; \
gb->cpu_reg.f.f_bits.h = ((gb->cpu_reg.a ^ r ^ temp) & 0x10) > 0; \
gb->cpu_reg.f.f_bits.n = 1; \
gb->cpu_reg.f.f_bits.z = ((temp & 0xFF) == 0x00); \
}
#endif /* PGB_INTRIN_SBC */
#if defined(PGB_INTRIN_ADC)
# define PGB_INSTR_ADC_R8(r,cin) \
{ \
uint8_t temp; \
gb->cpu_reg.f.f_bits.c = PGB_INTRIN_ADC(gb->cpu_reg.a,r,cin,temp);\
gb->cpu_reg.f.f_bits.h = ((gb->cpu_reg.a ^ r ^ temp) & 0x10) > 0; \
gb->cpu_reg.f.f_bits.n = 0; \
gb->cpu_reg.f.f_bits.z = (temp == 0x00); \
gb->cpu_reg.a = temp; \
}
#else
# define PGB_INSTR_ADC_R8(r,cin) \
{ \
uint16_t temp = gb->cpu_reg.a + r + cin; \
gb->cpu_reg.f.f_bits.c = (temp & 0xFF00) ? 1 : 0; \
gb->cpu_reg.f.f_bits.h = ((gb->cpu_reg.a ^ r ^ temp) & 0x10) > 0; \
gb->cpu_reg.f.f_bits.n = 0; \
gb->cpu_reg.f.f_bits.z = ((temp & 0xFF) == 0x00); \
gb->cpu_reg.a = (temp & 0xFF); \
}
#endif /* PGB_INTRIN_ADC */
#define PGB_INSTR_INC_R8(r) \
r++; \
gb->cpu_reg.f.f_bits.h = ((r & 0x0F) == 0x00); \
gb->cpu_reg.f.f_bits.n = 0; \
gb->cpu_reg.f.f_bits.z = (r == 0x00)
#define PGB_INSTR_DEC_R8(r) \
r--; \
gb->cpu_reg.f.f_bits.h = ((r & 0x0F) == 0x0F); \
gb->cpu_reg.f.f_bits.n = 1; \
gb->cpu_reg.f.f_bits.z = (r == 0x00)
#define PGB_INSTR_XOR_R8(r) \
gb->cpu_reg.a ^= r; \
gb->cpu_reg.f.reg = 0; \
gb->cpu_reg.f.f_bits.z = (gb->cpu_reg.a == 0x00)
#define PGB_INSTR_OR_R8(r) \
gb->cpu_reg.a |= r; \
gb->cpu_reg.f.reg = 0; \
gb->cpu_reg.f.f_bits.z = (gb->cpu_reg.a == 0x00)
#define PGB_INSTR_AND_R8(r) \
gb->cpu_reg.a &= r; \
gb->cpu_reg.f.reg = 0; \
gb->cpu_reg.f.f_bits.z = (gb->cpu_reg.a == 0x00); \
gb->cpu_reg.f.f_bits.h = 1
#if PEANUT_GB_IS_LITTLE_ENDIAN
# define PEANUT_GB_GET_LSB16(x) (x & 0xFF)
# define PEANUT_GB_GET_MSB16(x) (x >> 8)
# define PEANUT_GB_GET_MSN16(x) (x >> 12)
# define PEANUT_GB_U8_TO_U16(h,l) ((l) | ((h) << 8))
#else
# define PEANUT_GB_GET_LSB16(x) (x >> 8)
# define PEANUT_GB_GET_MSB16(x) (x & 0xFF)
# define PEANUT_GB_GET_MSN16(x) ((x & 0xF0) >> 4)
# define PEANUT_GB_U8_TO_U16(h,l) ((h) | ((l) << 8))
#endif
struct cpu_registers_s
{
/* Change register order if big endian.
* Macro receives registers in little endian order. */
#if PEANUT_GB_IS_LITTLE_ENDIAN
# define PEANUT_GB_LE_REG(x,y) x,y
#else
# define PEANUT_GB_LE_REG(x,y) y,x
#endif
/* Define specific bits of Flag register. */
union {
struct {
uint8_t c: 1; /* Carry flag. */
uint8_t h: 1; /* Half carry flag. */
uint8_t n: 1; /* Add/sub flag. */
uint8_t z: 1; /* Zero flag. */
} f_bits;
uint8_t reg;
} f;
uint8_t a;
union
{
struct
{
uint8_t PEANUT_GB_LE_REG(c,b);
} bytes;
uint16_t reg;
} bc;
union
{
struct
{
uint8_t PEANUT_GB_LE_REG(e,d);
} bytes;
uint16_t reg;
} de;
union
{
struct
{
uint8_t PEANUT_GB_LE_REG(l,h);
} bytes;
uint16_t reg;
} hl;
/* Stack pointer */
union
{
struct
{
uint8_t PEANUT_GB_LE_REG(p, s);
} bytes;
uint16_t reg;
} sp;
/* Program counter */
union
{
struct
{
uint8_t PEANUT_GB_LE_REG(c, p);
} bytes;
uint16_t reg;
} pc;
#undef PEANUT_GB_LE_REG
};
struct count_s
{
uint_fast16_t lcd_count; /* LCD Timing */
uint_fast16_t div_count; /* Divider Register Counter */
uint_fast16_t tima_count; /* Timer Counter */
uint_fast16_t serial_count; /* Serial Counter */
uint_fast32_t rtc_count; /* RTC Counter */
};
#if ENABLE_LCD
/* Bit mask for the shade of pixel to display */
#define LCD_COLOUR 0x03
# if PEANUT_GB_12_COLOUR
/**
* Bit mask for whether a pixel is OBJ0, OBJ1, or BG. Each may have a different
* palette when playing a DMG game on CGB.
*/
#define LCD_PALETTE_OBJ 0x10
#define LCD_PALETTE_BG 0x20
/**
* Bit mask for the two bits listed above.
* LCD_PALETTE_ALL == 0b00 --> OBJ0
* LCD_PALETTE_ALL == 0b01 --> OBJ1
* LCD_PALETTE_ALL == 0b10 --> BG
* LCD_PALETTE_ALL == 0b11 --> NOT POSSIBLE
*/
#define LCD_PALETTE_ALL 0x30
# endif
#endif
/**
* Errors that may occur during emulation.
*/
enum gb_error_e
{
GB_UNKNOWN_ERROR = 0,
GB_INVALID_OPCODE,
GB_INVALID_READ,
GB_INVALID_WRITE,
GB_HALT_FOREVER,
GB_INVALID_SIZE,
GB_INVALID_MAX
};
/**
* Errors that may occur during library initialisation.
*/
enum gb_init_error_e
{
GB_INIT_NO_ERROR = 0,
GB_INIT_CARTRIDGE_UNSUPPORTED,
GB_INIT_INVALID_CHECKSUM,
GB_INIT_INVALID_MAX
};
/**
* Return codes for serial receive function, mainly for clarity.
*/
enum gb_serial_rx_ret_e
{
GB_SERIAL_RX_SUCCESS = 0,
GB_SERIAL_RX_NO_CONNECTION = 1
};
union cart_rtc
{
struct
{
uint8_t sec;
uint8_t min;
uint8_t hour;
uint8_t yday;
uint8_t high;
} reg;
uint8_t bytes[5];
};
/**
* Emulator context.
*
* Only values within the `direct` struct may be modified directly by the
* front-end implementation. Other variables must not be modified.
*/
struct gb_s
{
/**
* Return byte from ROM at given address.
*
* \param gb_s emulator context
* \param addr address
* \return byte at address in ROM
*/
uint8_t (*gb_rom_read)(struct gb_s*, const uint_fast32_t addr);
/**
* Return byte from cart RAM at given address.
*
* \param gb_s emulator context
* \param addr address
* \return byte at address in RAM
*/
uint8_t (*gb_cart_ram_read)(struct gb_s*, const uint_fast32_t addr);
/**
* Write byte to cart RAM at given address.
*
* \param gb_s emulator context
* \param addr address
* \param val value to write to address in RAM
*/
void (*gb_cart_ram_write)(struct gb_s*, const uint_fast32_t addr,
const uint8_t val);
/**
* Notify front-end of error.
*
* \param gb_s emulator context
* \param gb_error_e error code
* \param addr address of where error occurred
*/
void (*gb_error)(struct gb_s*, const enum gb_error_e, const uint16_t addr);
/* Transmit one byte and return the received byte. */
void (*gb_serial_tx)(struct gb_s*, const uint8_t tx);
enum gb_serial_rx_ret_e (*gb_serial_rx)(struct gb_s*, uint8_t* rx);
/* Read byte from boot ROM at given address. */
uint8_t (*gb_boot_rom_read)(struct gb_s*, const uint_fast16_t addr);
struct
{
bool gb_halt : 1;
bool gb_ime : 1;
bool gb_frame : 1; /* New frame drawn. */
bool lcd_blank : 1;
};
/* Cartridge information:
* Memory Bank Controller (MBC) type. */
int8_t mbc;
/* Whether the MBC has internal RAM. */
uint8_t cart_ram;
/* Number of ROM banks in cartridge. */
uint16_t num_rom_banks_mask;
/* Number of RAM banks in cartridge. Ignore for MBC2. */
uint8_t num_ram_banks;
uint16_t selected_rom_bank;
/* WRAM and VRAM bank selection not available. */
uint8_t cart_ram_bank;
uint8_t enable_cart_ram;
/* Cartridge ROM/RAM mode select. */
uint8_t cart_mode_select;
union cart_rtc rtc_latched, rtc_real;
struct cpu_registers_s cpu_reg;
//struct gb_registers_s gb_reg;
struct count_s counter;
/* TODO: Allow implementation to allocate WRAM, VRAM and Frame Buffer. */
uint8_t wram[WRAM_SIZE];
uint8_t vram[VRAM_SIZE];
uint8_t oam[OAM_SIZE];
uint8_t hram_io[HRAM_IO_SIZE];
struct
{
/**
* Draw line on screen.
*
* \param gb_s emulator context
* \param pixels The 160 pixels to draw.
* Bits 1-0 are the colour to draw.
* Bits 5-4 are the palette, where:
* OBJ0 = 0b00,
* OBJ1 = 0b01,
* BG = 0b10
* Other bits are undefined.
* Bits 5-4 are only required by front-ends
* which want to use a different colour for
* different object palettes. This is what
* the Game Boy Color (CGB) does to DMG
* games.
* \param line Line to draw pixels on. This is
* guaranteed to be between 0-144 inclusive.
*/
void (*lcd_draw_line)(struct gb_s *gb,
const uint8_t *pixels,
const uint_fast8_t line);
/* Palettes */
uint8_t bg_palette[4];
uint8_t sp_palette[8];
uint8_t window_clear;
uint8_t WY;
/* Only support 30fps frame skip. */
bool frame_skip_count : 1;
bool interlace_count : 1;
} display;
/**
* Variables that may be modified directly by the front-end.
* This method seems to be easier and possibly less overhead than
* calling a function to modify these variables each time.
*
* None of this is thread-safe.
*/
struct
{
/* Set to enable interlacing. Interlacing will start immediately
* (at the next line drawing).
*/
bool interlace : 1;
bool frame_skip : 1;
union
{
struct
{
/* Using this bitfield is deprecated due to
* portability concerns. It is recommended to
* use the JOYPAD_* defines instead.
*/
bool a : 1;
bool b : 1;
bool select : 1;
bool start : 1;
bool right : 1;
bool left : 1;
bool up : 1;
bool down : 1;
} joypad_bits;
uint8_t joypad;
};
/* Implementation defined data. Set to NULL if not required. */
void *priv;
} direct;
};
#ifndef PEANUT_GB_HEADER_ONLY
#define IO_JOYP 0x00
#define IO_SB 0x01
#define IO_SC 0x02
#define IO_DIV 0x04
#define IO_TIMA 0x05
#define IO_TMA 0x06
#define IO_TAC 0x07
#define IO_IF 0x0F
#define IO_LCDC 0x40
#define IO_STAT 0x41
#define IO_SCY 0x42
#define IO_SCX 0x43
#define IO_LY 0x44
#define IO_LYC 0x45
#define IO_DMA 0x46
#define IO_BGP 0x47
#define IO_OBP0 0x48
#define IO_OBP1 0x49
#define IO_WY 0x4A
#define IO_WX 0x4B
#define IO_BOOT 0x50
#define IO_IE 0xFF
#define IO_TAC_RATE_MASK 0x3
#define IO_TAC_ENABLE_MASK 0x4
/* LCD Mode defines. */
#define IO_STAT_MODE_HBLANK 0
#define IO_STAT_MODE_VBLANK 1
#define IO_STAT_MODE_SEARCH_OAM 2
#define IO_STAT_MODE_SEARCH_TRANSFER 3
#define IO_STAT_MODE_VBLANK_OR_TRANSFER_MASK 0x1
/**
* Internal function used to read bytes.
* addr is host platform endian.
*/
uint8_t __gb_read(struct gb_s *gb, uint16_t addr)
{
switch(PEANUT_GB_GET_MSN16(addr))
{
case 0x0:
/* IO_BOOT is only set to 1 if gb->gb_boot_rom_read was not NULL
* on reset. */
if(gb->hram_io[IO_BOOT] == 0 && addr < 0x0100)
{
return gb->gb_boot_rom_read(gb, addr);
}
/* Fallthrough */
case 0x1:
case 0x2:
case 0x3:
return gb->gb_rom_read(gb, addr);
case 0x4:
case 0x5:
case 0x6:
case 0x7:
if(gb->mbc == 1 && gb->cart_mode_select)
return gb->gb_rom_read(gb,
addr + ((gb->selected_rom_bank & 0x1F) - 1) * ROM_BANK_SIZE);
else
return gb->gb_rom_read(gb, addr + (gb->selected_rom_bank - 1) * ROM_BANK_SIZE);
case 0x8:
case 0x9:
return gb->vram[addr - VRAM_ADDR];
case 0xA:
case 0xB:
if(gb->mbc == 3 && gb->cart_ram_bank >= 0x08)
{
return gb->rtc_latched.bytes[gb->cart_ram_bank - 0x08];
}
else if(gb->cart_ram && gb->enable_cart_ram)
{
if(gb->mbc == 2)
{
/* Only 9 bits are available in address. */
addr &= 0x1FF;
return gb->gb_cart_ram_read(gb, addr);
}
else if((gb->cart_mode_select || gb->mbc != 1) &&
gb->cart_ram_bank < gb->num_ram_banks)
{
return gb->gb_cart_ram_read(gb, addr - CART_RAM_ADDR +
(gb->cart_ram_bank * CRAM_BANK_SIZE));
}
else
return gb->gb_cart_ram_read(gb, addr - CART_RAM_ADDR);
}
return 0xFF;
case 0xC:
case 0xD:
return gb->wram[addr - WRAM_0_ADDR];
case 0xE:
return gb->wram[addr - ECHO_ADDR];
case 0xF:
if(addr < OAM_ADDR)
return gb->wram[addr - ECHO_ADDR];
if(addr < UNUSED_ADDR)
return gb->oam[addr - OAM_ADDR];
/* Unusable memory area. Reading from this area returns 0xFF.*/
if(addr < IO_ADDR)
return 0xFF;
/* APU registers. */
if((addr >= 0xFF10) && (addr <= 0xFF3F))
{
#if ENABLE_SOUND
return audio_read(addr);
#else
static const uint8_t ortab[] = {
0x80, 0x3f, 0x00, 0xff, 0xbf,
0xff, 0x3f, 0x00, 0xff, 0xbf,
0x7f, 0xff, 0x9f, 0xff, 0xbf,
0xff, 0xff, 0x00, 0x00, 0xbf,
0x00, 0x00, 0x70,
0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
};
return gb->hram_io[addr - IO_ADDR] | ortab[addr - IO_ADDR];
#endif
}
/* HRAM */
if(addr >= IO_ADDR)
return gb->hram_io[addr - IO_ADDR];
}
/* Return address that caused read error. */
(gb->gb_error)(gb, GB_INVALID_READ, addr);
PGB_UNREACHABLE();
}
/**
* Internal function used to write bytes.
*/
void __gb_write(struct gb_s *gb, uint_fast16_t addr, uint8_t val)
{
switch(PEANUT_GB_GET_MSN16(addr))
{
case 0x0:
case 0x1:
/* Set RAM enable bit. MBC2 is handled in fall-through. */
if(gb->mbc > 0 && gb->mbc != 2 && gb->cart_ram)
{
gb->enable_cart_ram = ((val & 0x0F) == 0x0A);
return;
}
/* Intentional fall through. */
case 0x2:
if(gb->mbc == 5)
{
gb->selected_rom_bank = (gb->selected_rom_bank & 0x100) | val;
gb->selected_rom_bank =
gb->selected_rom_bank & gb->num_rom_banks_mask;
return;
}
/* Intentional fall through. */
case 0x3:
if(gb->mbc == 1)
{
//selected_rom_bank = val & 0x7;
gb->selected_rom_bank = (val & 0x1F) | (gb->selected_rom_bank & 0x60);
if((gb->selected_rom_bank & 0x1F) == 0x00)
gb->selected_rom_bank++;
}
else if(gb->mbc == 2)
{
/* If bit 8 is 1, then set ROM bank number. */
if(addr & 0x100)
{
gb->selected_rom_bank = val & 0x0F;
/* Setting ROM bank to 0, sets it to 1. */
if(!gb->selected_rom_bank)
gb->selected_rom_bank++;
}
/* Otherwise set whether RAM is enabled or not. */
else
{
gb->enable_cart_ram = ((val & 0x0F) == 0x0A);
return;
}
}
else if(gb->mbc == 3)
{
gb->selected_rom_bank = val & 0x7F;
if(!gb->selected_rom_bank)
gb->selected_rom_bank++;
}
else if(gb->mbc == 5)
gb->selected_rom_bank = (val & 0x01) << 8 | (gb->selected_rom_bank & 0xFF);
gb->selected_rom_bank = gb->selected_rom_bank & gb->num_rom_banks_mask;
return;
case 0x4:
case 0x5:
if(gb->mbc == 1)
{
gb->cart_ram_bank = (val & 3);
gb->selected_rom_bank = ((val & 3) << 5) | (gb->selected_rom_bank & 0x1F);
gb->selected_rom_bank = gb->selected_rom_bank & gb->num_rom_banks_mask;
}
else if(gb->mbc == 3)
gb->cart_ram_bank = val;
else if(gb->mbc == 5)
gb->cart_ram_bank = (val & 0x0F);
return;
case 0x6:
case 0x7:
val &= 1;
if(gb->mbc == 3 && val && gb->cart_mode_select == 0)
memcpy(&gb->rtc_latched.bytes, &gb->rtc_real.bytes, sizeof(gb->rtc_latched.bytes));
gb->cart_mode_select = val;
return;
case 0x8:
case 0x9:
gb->vram[addr - VRAM_ADDR] = val;
return;
case 0xA:
case 0xB:
if(gb->mbc == 3 && gb->cart_ram_bank >= 0x08)
{
const uint8_t rtc_reg_mask[5] = {
0x3F, 0x3F, 0x1F, 0xFF, 0xC1
};
uint8_t reg = gb->cart_ram_bank - 0x08;
//if(reg == 0) gb->counter.rtc_count = 0;
gb->rtc_real.bytes[reg] = val & rtc_reg_mask[reg];
}
/* Do not write to RAM if unavailable or disabled. */
else if(gb->cart_ram && gb->enable_cart_ram)
{
if(gb->mbc == 2)
{
/* Only 9 bits are available in address. */
addr &= 0x1FF;
/* Data is only 4 bits wide in MBC2 RAM. */
val &= 0x0F;
gb->gb_cart_ram_write(gb, addr, val);
}
else if(gb->cart_mode_select &&
gb->cart_ram_bank < gb->num_ram_banks)
{
gb->gb_cart_ram_write(gb,
addr - CART_RAM_ADDR + (gb->cart_ram_bank * CRAM_BANK_SIZE), val);
}
else if(gb->num_ram_banks)
gb->gb_cart_ram_write(gb, addr - CART_RAM_ADDR, val);
}
return;
case 0xC:
gb->wram[addr - WRAM_0_ADDR] = val;
return;
case 0xD:
gb->wram[addr - WRAM_1_ADDR + WRAM_BANK_SIZE] = val;
return;
case 0xE:
gb->wram[addr - ECHO_ADDR] = val;
return;
case 0xF:
if(addr < OAM_ADDR)
{