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Diffstat (limited to 'src/devices/cpu/lr35902/lr35902.cpp')
-rw-r--r-- | src/devices/cpu/lr35902/lr35902.cpp | 354 |
1 files changed, 354 insertions, 0 deletions
diff --git a/src/devices/cpu/lr35902/lr35902.cpp b/src/devices/cpu/lr35902/lr35902.cpp new file mode 100644 index 00000000000..02cb785e1ff --- /dev/null +++ b/src/devices/cpu/lr35902/lr35902.cpp @@ -0,0 +1,354 @@ +// license:BSD-3-Clause +// copyright-holders:Wilbert Pol +/*************************************************************/ +/** **/ +/** lr35902.c **/ +/** **/ +/** This file contains implementation for the GameBoy CPU. **/ +/** See lr35902.h for the relevant definitions. Please, note**/ +/** that this code can not be used to emulate a generic Z80 **/ +/** because the GameBoy version of it differs from Z80 in **/ +/** many ways. **/ +/** **/ +/** Orginal cpu code (PlayBoy) Carsten Sorensen 1998 **/ +/** MESS modifications Hans de Goede 1998 **/ +/** Adapted to new cpuintrf Juergen Buchmueller 2000 **/ +/** Adapted to new cpuintrf Anthony Kruize 2002 **/ +/** Changed reset function to **/ +/** reset all registers instead **/ +/** of just AF. Wilbert Pol 2004 **/ +/** **/ +/** 1.1: **/ +/** Removed dependency on the mess gameboy driver **/ +/** **/ +/** 1.2: **/ +/** Fixed cycle count for taking an interrupt **/ +/** Fixed cycle count for BIT X,(HL) instructions **/ +/** Fixed flags in RRCA instruction **/ +/** Fixed DAA instruction **/ +/** Fixed flags in ADD SP,n8 instruction **/ +/** Fixed flags in LD HL,SP+n8 instruction **/ +/** **/ +/** 1.3: **/ +/** Improved triggering of the HALT bug **/ +/** Added 4 cycle penalty when leaving HALT state for **/ +/** newer versions of the cpu core **/ +/** **/ +/** 1.4: **/ +/** Split fetch and execute cycles. **/ +/** **/ +/*************************************************************/ + +#include "emu.h" +#include "debugger.h" +#include "lr35902.h" + +/* Flag bit definitions */ +enum lr35902_flag +{ + FLAG_C = 0x10, + FLAG_H = 0x20, + FLAG_N = 0x40, + FLAG_Z = 0x80 +}; + +#define IME 0x01 +#define HALTED 0x02 + + +//************************************************************************** +// LR35902 DEVICE +//************************************************************************** + +const device_type LR35902 = &device_creator<lr35902_cpu_device>; + + +lr35902_cpu_device::lr35902_cpu_device(const machine_config &mconfig, const char *tag, device_t *owner, UINT32 clock) + : cpu_device(mconfig, LR35902, "LR35902", tag, owner, clock, "lr35902", __FILE__) + , m_program_config("program", ENDIANNESS_LITTLE, 8, 16, 0) + , m_A(0) + , m_F(0) + , m_B(0) + , m_C(0) + , m_D(0) + , m_E(0) + , m_H(0) + , m_L(0) + , m_SP(0) + , m_PC(0) + , m_IE(0) + , m_IF(0) + , m_enable(0) + , m_has_halt_bug(false) + , m_timer_func(*this) + , m_incdec16_func(*this) +{ +} + + +/****************************************************************************/ +/* Memory functions */ +/****************************************************************************/ + +inline void lr35902_cpu_device::cycles_passed(UINT8 cycles) +{ + m_icount -= cycles / m_gb_speed; + m_timer_func( cycles ); +} + + +inline UINT8 lr35902_cpu_device::mem_read_byte( UINT16 addr ) +{ + UINT8 data = m_program->read_byte( addr ); + cycles_passed( 4 ); + return data; +} + + +inline void lr35902_cpu_device::mem_write_byte( UINT16 addr, UINT8 data ) +{ + m_program->write_byte( addr, data ); + cycles_passed( 4 ); +} + + +inline UINT16 lr35902_cpu_device::mem_read_word( UINT16 addr ) +{ + UINT16 data = mem_read_byte( addr ); + data |= ( mem_read_byte( addr + 1 ) << 8 ); + return data; +} + + +inline void lr35902_cpu_device::mem_write_word( UINT16 addr, UINT16 data ) +{ + mem_write_byte( addr, data & 0xFF ); + mem_write_byte( addr + 1, data >> 8 ); +} + + +void lr35902_cpu_device::device_start() +{ + m_device = this; + m_program = &space(AS_PROGRAM); + + // resolve callbacks + m_timer_func.resolve_safe(); + m_incdec16_func.resolve_safe(); + + // register for save states + save_item(NAME(m_A)); + save_item(NAME(m_F)); + save_item(NAME(m_B)); + save_item(NAME(m_C)); + save_item(NAME(m_D)); + save_item(NAME(m_E)); + save_item(NAME(m_H)); + save_item(NAME(m_L)); + save_item(NAME(m_PC)); + save_item(NAME(m_SP)); + save_item(NAME(m_IE)); + save_item(NAME(m_IF)); + save_item(NAME(m_irq_state)); + save_item(NAME(m_handle_ei_delay)); + save_item(NAME(m_execution_state)); + save_item(NAME(m_op)); + save_item(NAME(m_gb_speed)); + save_item(NAME(m_gb_speed_change_pending)); + save_item(NAME(m_enable)); + save_item(NAME(m_handle_halt_bug)); + + // Register state for debugger + state_add( LR35902_PC, "PC", m_PC ).callimport().callexport().formatstr("%04X"); + state_add( LR35902_SP, "SP", m_SP ).callimport().callexport().formatstr("%04X"); + state_add( LR35902_A, "A", m_A ).callimport().callexport().formatstr("%02X"); + state_add( LR35902_F, "F", m_F ).callimport().callexport().formatstr("%02X"); + state_add( LR35902_B, "B", m_B ).callimport().callexport().formatstr("%02X"); + state_add( LR35902_C, "C", m_C ).callimport().callexport().formatstr("%02X"); + state_add( LR35902_D, "D", m_D ).callimport().callexport().formatstr("%02X"); + state_add( LR35902_E, "E", m_E ).callimport().callexport().formatstr("%02X"); + state_add( LR35902_H, "H", m_H ).callimport().callexport().formatstr("%02X"); + state_add( LR35902_L, "L", m_L ).callimport().callexport().formatstr("%02X"); + state_add( LR35902_IRQ_STATE, "IRQ", m_enable ).callimport().callexport().formatstr("%02X"); + state_add( LR35902_IE, "IE", m_IE ).callimport().callexport().formatstr("%02X"); + state_add( LR35902_IF, "IF", m_IF ).callimport().callexport().formatstr("%02X"); + + state_add(STATE_GENPC, "curpc", m_PC).callimport().callexport().formatstr("%8s").noshow(); + state_add(STATE_GENFLAGS, "GENFLAGS", m_F).mask(0xf0).formatstr("%8s").noshow(); + + m_icountptr = &m_icount; +} + + +void lr35902_cpu_device::state_string_export(const device_state_entry &entry, std::string &str) +{ + switch (entry.index()) + { + case LR35902_SPEED: + strprintf(str, "%02X", 0x7E | ((m_gb_speed - 1) << 7) | m_gb_speed_change_pending); + break; + + case STATE_GENFLAGS: + strprintf(str, "%c%c%c%c", + m_F & FLAG_Z ? 'Z' : '.', + m_F & FLAG_N ? 'N' : '.', + m_F & FLAG_H ? 'H' : '.', + m_F & FLAG_C ? 'C' : '.' + ); + break; + } +} + +void lr35902_cpu_device::device_reset() +{ + m_A = 0x00; + m_F = 0x00; + m_B = 0x00; + m_C = 0x00; + m_D = 0x00; + m_E = 0x00; + m_H = 0x00; + m_L = 0x00; + m_SP = 0x0000; + m_PC = 0x0000; + + m_enable = 0; + m_IE = 0; + m_IF = 0; + + m_execution_state = 0; + m_handle_halt_bug = false; + m_handle_ei_delay = false; + m_gb_speed_change_pending = 0; + m_gb_speed = 1; +} + + +offs_t lr35902_cpu_device::disasm_disassemble(char *buffer, offs_t pc, const UINT8 *oprom, const UINT8 *opram, UINT32 options) +{ + extern CPU_DISASSEMBLE( lr35902 ); + return CPU_DISASSEMBLE_NAME(lr35902)(this, buffer, pc, oprom, opram, options); +} + + +void lr35902_cpu_device::check_interrupts() +{ + UINT8 irq = m_IE & m_IF; + + /* Interrupts should be taken after the first instruction after an EI instruction */ + if (m_handle_ei_delay) { + m_handle_ei_delay = false; + return; + } + + /* + logerror("Attempting to process LR35902 Interrupt IRQ $%02X\n", irq); + logerror("Attempting to process LR35902 Interrupt IE $%02X\n", m_IE); + logerror("Attempting to process LR35902 Interrupt IF $%02X\n", m_IF); + */ + if (irq) + { + int irqline = 0; + /* + logerror("LR35902 Interrupt IRQ $%02X\n", irq); + */ + + for( ; irqline < 5; irqline++ ) + { + if( irq & (1<<irqline) ) + { + if (m_enable & HALTED) + { + m_enable &= ~HALTED; + m_PC++; + if ( m_has_halt_bug ) { + if ( ! ( m_enable & IME ) ) { + /* Old cpu core (dmg/mgb/sgb) */ + m_handle_halt_bug = true; + } + } else { + /* New cpu core (cgb/agb/ags) */ + /* Adjust for internal syncing with video core */ + /* This feature needs more investigation */ + if ( irqline < 2 ) { + cycles_passed( 4 ); + } + } + } + if ( m_enable & IME ) { + m_enable &= ~IME; + m_IF &= ~(1 << irqline); + cycles_passed( 12 ); + m_SP -= 2; + mem_write_word( m_SP, m_PC ); + m_PC = 0x40 + irqline * 8; + /*logerror("LR35902 Interrupt PC $%04X\n", m_PC );*/ + return; + } + } + } + } +} + + +/************************************************************/ +/*** Execute lr35902 code for m_icount cycles. ***/ +/************************************************************/ +void lr35902_cpu_device::execute_run() +{ + do + { + if ( m_execution_state ) { + UINT8 x; + /* Execute instruction */ + switch( m_op ) { +#include "opc_main.inc" + default: + // actually this should lock up the cpu! + logerror("LR35902: Illegal opcode $%02X @ %04X\n", m_op, m_PC); + break; + } + } else { + /* Fetch and count cycles */ + check_interrupts(); + debugger_instruction_hook(this, m_PC); + if ( m_enable & HALTED ) { + cycles_passed( 4 ); + m_execution_state = 1; + } else { + m_op = mem_read_byte( m_PC++ ); + if ( m_handle_halt_bug ) { + m_PC--; + m_handle_halt_bug = false; + } + } + } + m_execution_state ^= 1; + } while (m_icount > 0); +} + + +void lr35902_cpu_device::execute_set_input( int inptnum, int state ) +{ + m_irq_state = state; + if( state == ASSERT_LINE ) + { + m_IF |= (0x01 << inptnum); + } + else + { + m_IF &= ~(0x01 << inptnum); + } +} + + +UINT8 lr35902_cpu_device::get_speed() +{ + return 0x7E | ( ( m_gb_speed - 1 ) << 7 ) | m_gb_speed_change_pending; +} + + +void lr35902_cpu_device::set_speed( UINT8 speed_request ) +{ + m_gb_speed_change_pending = speed_request & 0x01; +} |