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Gb_Cpu.cpp
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Gb_Cpu.cpp
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// Game_Music_Emu https://bitbucket.org/mpyne/game-music-emu/
#include "Gb_Cpu.h"
#include <string.h>
//#include "gb_cpu_log.h"
/* Copyright (C) 2003-2006 Shay Green. This module is free software; you
can redistribute it and/or modify it under the terms of the GNU Lesser
General Public License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version. This
module is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
details. You should have received a copy of the GNU Lesser General Public
License along with this module; if not, write to the Free Software Foundation,
Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */
#include "gb_cpu_io.h"
#include "blargg_source.h"
// Common instructions:
//
// 365880 FA LD A,IND16
// 355863 20 JR NZ
// 313655 21 LD HL,IMM
// 274580 28 JR Z
// 252878 FE CMP IMM
// 230541 7E LD A,(HL)
// 226209 2A LD A,(HL+)
// 217467 CD CALL
// 212034 C9 RET
// 208376 CB CB prefix
//
// 27486 CB 7E BIT 7,(HL)
// 15925 CB 76 BIT 6,(HL)
// 13035 CB 19 RR C
// 11557 CB 7F BIT 7,A
// 10898 CB 37 SWAP A
// 10208 CB 66 BIT 4,(HL)
#if BLARGG_NONPORTABLE
#define PAGE_OFFSET( addr ) (addr)
#else
#define PAGE_OFFSET( addr ) ((addr) & (page_size - 1))
#endif
inline void Gb_Cpu::set_code_page( int i, uint8_t* p )
{
state->code_map [i] = p - PAGE_OFFSET( i * (blargg_long) page_size );
}
void Gb_Cpu::reset( void* unmapped )
{
check( state == &state_ );
state = &state_;
state_.remain = 0;
for ( int i = 0; i < page_count + 1; i++ )
set_code_page( i, (uint8_t*) unmapped );
memset( &r, 0, sizeof r );
//interrupts_enabled = false;
blargg_verify_byte_order();
}
void Gb_Cpu::map_code( gb_addr_t start, unsigned size, void* data )
{
// address range must begin and end on page boundaries
require( start % page_size == 0 );
require( size % page_size == 0 );
unsigned first_page = start / page_size;
for ( unsigned i = size / page_size; i--; )
set_code_page( first_page + i, (uint8_t*) data + i * page_size );
}
#define READ( addr ) CPU_READ( this, (addr), s.remain )
#define WRITE( addr, data ) {CPU_WRITE( this, (addr), (data), s.remain );}
#define READ_FAST( addr, out ) CPU_READ_FAST( this, (addr), s.remain, out )
#define READ_PROG( addr ) (s.code_map [(addr) >> page_shift] [PAGE_OFFSET( addr )])
unsigned const z_flag = 0x80;
unsigned const n_flag = 0x40;
unsigned const h_flag = 0x20;
unsigned const c_flag = 0x10;
bool Gb_Cpu::run( blargg_long cycle_count )
{
state_.remain = blargg_ulong (cycle_count + clocks_per_instr) / clocks_per_instr;
state_t s;
this->state = &s;
memcpy( &s, &this->state_, sizeof s );
#if BLARGG_BIG_ENDIAN
#define R8( n ) (r8_ [n])
#elif BLARGG_LITTLE_ENDIAN
#define R8( n ) (r8_ [(n) ^ 1])
#else
#error "Byte order of CPU must be known"
#endif
union {
core_regs_t rg; // individual registers
struct {
uint16_t bc, de, hl, unused; // pairs
} rp;
uint8_t r8_ [8]; // indexed registers (use R8 macro due to endian dependence)
uint16_t r16 [4]; // indexed pairs
};
BOOST_STATIC_ASSERT( sizeof rg == 8 && sizeof rp == 8 );
rg = r;
unsigned pc = r.pc;
unsigned sp = r.sp;
unsigned flags = r.flags;
loop:
check( (unsigned long) pc < 0x10000 );
check( (unsigned long) sp < 0x10000 );
check( (flags & ~0xF0) == 0 );
uint8_t const* instr = s.code_map [pc >> page_shift];
unsigned op;
// TODO: eliminate this special case
#if BLARGG_NONPORTABLE
op = instr [pc];
pc++;
instr += pc;
#else
instr += PAGE_OFFSET( pc );
op = *instr++;
pc++;
#endif
#define GET_ADDR() GET_LE16( instr )
if ( !--s.remain )
goto stop;
unsigned data;
data = *instr;
#ifdef GB_CPU_LOG_H
gb_cpu_log( "new", pc - 1, op, data, instr [1] );
#endif
switch ( op )
{
// TODO: more efficient way to handle negative branch that wraps PC around
#define BRANCH( cond )\
{\
pc++;\
int offset = (int8_t) data;\
if ( !(cond) ) goto loop;\
pc = uint16_t (pc + offset);\
goto loop;\
}
// Most Common
case 0x20: // JR NZ
BRANCH( !(flags & z_flag) )
case 0x21: // LD HL,IMM (common)
rp.hl = GET_ADDR();
pc += 2;
goto loop;
case 0x28: // JR Z
BRANCH( flags & z_flag )
{
unsigned temp;
case 0xF0: // LD A,(0xFF00+imm)
temp = data | 0xFF00;
pc++;
goto ld_a_ind_comm;
case 0xF2: // LD A,(0xFF00+C)
temp = rg.c | 0xFF00;
goto ld_a_ind_comm;
case 0x0A: // LD A,(BC)
temp = rp.bc;
goto ld_a_ind_comm;
case 0x3A: // LD A,(HL-)
temp = rp.hl;
rp.hl = temp - 1;
goto ld_a_ind_comm;
case 0x1A: // LD A,(DE)
temp = rp.de;
goto ld_a_ind_comm;
case 0x2A: // LD A,(HL+) (common)
temp = rp.hl;
rp.hl = temp + 1;
goto ld_a_ind_comm;
case 0xFA: // LD A,IND16 (common)
temp = GET_ADDR();
pc += 2;
ld_a_ind_comm:
READ_FAST( temp, rg.a );
goto loop;
}
case 0xBE: // CMP (HL)
data = READ( rp.hl );
goto cmp_comm;
case 0xB8: // CMP B
case 0xB9: // CMP C
case 0xBA: // CMP D
case 0xBB: // CMP E
case 0xBC: // CMP H
case 0xBD: // CMP L
data = R8( op & 7 );
goto cmp_comm;
case 0xFE: // CMP IMM
pc++;
cmp_comm:
op = rg.a;
data = op - data;
sub_set_flags:
flags = ((op & 15) - (data & 15)) & h_flag;
flags |= (data >> 4) & c_flag;
flags |= n_flag;
if ( data & 0xFF )
goto loop;
flags |= z_flag;
goto loop;
case 0x46: // LD B,(HL)
case 0x4E: // LD C,(HL)
case 0x56: // LD D,(HL)
case 0x5E: // LD E,(HL)
case 0x66: // LD H,(HL)
case 0x6E: // LD L,(HL)
case 0x7E:{// LD A,(HL)
unsigned addr = rp.hl;
READ_FAST( addr, R8( (op >> 3) & 7 ) );
goto loop;
}
case 0xC4: // CNZ (next-most-common)
pc += 2;
if ( flags & z_flag )
goto loop;
call:
pc -= 2; // FALLTHRU
case 0xCD: // CALL (most-common)
data = pc + 2;
pc = GET_ADDR();
push:
sp = (sp - 1) & 0xFFFF;
WRITE( sp, data >> 8 );
sp = (sp - 1) & 0xFFFF;
WRITE( sp, data & 0xFF );
goto loop;
case 0xC8: // RNZ (next-most-common)
if ( !(flags & z_flag) )
goto loop;
// FALLTHRU
case 0xC9: // RET (most common)
ret:
pc = READ( sp );
pc += 0x100 * READ( sp + 1 );
sp = (sp + 2) & 0xFFFF;
goto loop;
case 0x00: // NOP
case 0x40: // LD B,B
case 0x49: // LD C,C
case 0x52: // LD D,D
case 0x5B: // LD E,E
case 0x64: // LD H,H
case 0x6D: // LD L,L
case 0x7F: // LD A,A
goto loop;
// CB Instructions
case 0xCB:
pc++;
// now data is the opcode
switch ( data ) {
{
int temp;
case 0x46: // BIT b,(HL)
case 0x4E:
case 0x56:
case 0x5E:
case 0x66:
case 0x6E:
case 0x76:
case 0x7E:
{
unsigned addr = rp.hl;
READ_FAST( addr, temp );
goto bit_comm;
}
case 0x40: case 0x41: case 0x42: case 0x43: // BIT b,r
case 0x44: case 0x45: case 0x47: case 0x48:
case 0x49: case 0x4A: case 0x4B: case 0x4C:
case 0x4D: case 0x4F: case 0x50: case 0x51:
case 0x52: case 0x53: case 0x54: case 0x55:
case 0x57: case 0x58: case 0x59: case 0x5A:
case 0x5B: case 0x5C: case 0x5D: case 0x5F:
case 0x60: case 0x61: case 0x62: case 0x63:
case 0x64: case 0x65: case 0x67: case 0x68:
case 0x69: case 0x6A: case 0x6B: case 0x6C:
case 0x6D: case 0x6F: case 0x70: case 0x71:
case 0x72: case 0x73: case 0x74: case 0x75:
case 0x77: case 0x78: case 0x79: case 0x7A:
case 0x7B: case 0x7C: case 0x7D: case 0x7F:
temp = R8( data & 7 );
bit_comm:
int bit = (~data >> 3) & 7;
flags &= ~n_flag;
flags |= h_flag | z_flag;
flags ^= (temp << bit) & z_flag;
goto loop;
}
case 0x86: // RES b,(HL)
case 0x8E:
case 0x96:
case 0x9E:
case 0xA6:
case 0xAE:
case 0xB6:
case 0xBE:
case 0xC6: // SET b,(HL)
case 0xCE:
case 0xD6:
case 0xDE:
case 0xE6:
case 0xEE:
case 0xF6:
case 0xFE: {
int temp = READ( rp.hl );
int bit = 1 << ((data >> 3) & 7);
temp &= ~bit;
if ( !(data & 0x40) )
bit = 0;
WRITE( rp.hl, temp | bit );
goto loop;
}
case 0xC0: case 0xC1: case 0xC2: case 0xC3: // SET b,r
case 0xC4: case 0xC5: case 0xC7: case 0xC8:
case 0xC9: case 0xCA: case 0xCB: case 0xCC:
case 0xCD: case 0xCF: case 0xD0: case 0xD1:
case 0xD2: case 0xD3: case 0xD4: case 0xD5:
case 0xD7: case 0xD8: case 0xD9: case 0xDA:
case 0xDB: case 0xDC: case 0xDD: case 0xDF:
case 0xE0: case 0xE1: case 0xE2: case 0xE3:
case 0xE4: case 0xE5: case 0xE7: case 0xE8:
case 0xE9: case 0xEA: case 0xEB: case 0xEC:
case 0xED: case 0xEF: case 0xF0: case 0xF1:
case 0xF2: case 0xF3: case 0xF4: case 0xF5:
case 0xF7: case 0xF8: case 0xF9: case 0xFA:
case 0xFB: case 0xFC: case 0xFD: case 0xFF:
R8( data & 7 ) |= 1 << ((data >> 3) & 7);
goto loop;
case 0x80: case 0x81: case 0x82: case 0x83: // RES b,r
case 0x84: case 0x85: case 0x87: case 0x88:
case 0x89: case 0x8A: case 0x8B: case 0x8C:
case 0x8D: case 0x8F: case 0x90: case 0x91:
case 0x92: case 0x93: case 0x94: case 0x95:
case 0x97: case 0x98: case 0x99: case 0x9A:
case 0x9B: case 0x9C: case 0x9D: case 0x9F:
case 0xA0: case 0xA1: case 0xA2: case 0xA3:
case 0xA4: case 0xA5: case 0xA7: case 0xA8:
case 0xA9: case 0xAA: case 0xAB: case 0xAC:
case 0xAD: case 0xAF: case 0xB0: case 0xB1:
case 0xB2: case 0xB3: case 0xB4: case 0xB5:
case 0xB7: case 0xB8: case 0xB9: case 0xBA:
case 0xBB: case 0xBC: case 0xBD: case 0xBF:
R8( data & 7 ) &= ~(1 << ((data >> 3) & 7));
goto loop;
{
int temp;
case 0x36: // SWAP (HL)
temp = READ( rp.hl );
goto swap_comm;
case 0x30: // SWAP B
case 0x31: // SWAP C
case 0x32: // SWAP D
case 0x33: // SWAP E
case 0x34: // SWAP H
case 0x35: // SWAP L
case 0x37: // SWAP A
temp = R8( data & 7 );
swap_comm:
op = (temp >> 4) | (temp << 4);
flags = 0;
goto shift_comm;
}
// Shift/Rotate
case 0x06: // RLC (HL)
case 0x16: // RL (HL)
case 0x26: // SLA (HL)
op = READ( rp.hl );
goto rl_comm;
case 0x20: case 0x21: case 0x22: case 0x23: case 0x24: case 0x25: case 0x27: // SLA A
case 0x00: case 0x01: case 0x02: case 0x03: case 0x04: case 0x05: case 0x07: // RLC A
case 0x10: case 0x11: case 0x12: case 0x13: case 0x14: case 0x15: case 0x17: // RL A
op = R8( data & 7 );
goto rl_comm;
case 0x3E: // SRL (HL)
data += 0x10; /* fallthrough */ // bump up to 0x4n to avoid preserving sign bit
case 0x1E: // RR (HL)
case 0x0E: // RRC (HL)
case 0x2E: // SRA (HL)
op = READ( rp.hl );
goto rr_comm;
case 0x38: case 0x39: case 0x3A: case 0x3B: case 0x3C: case 0x3D: case 0x3F: // SRL A
data += 0x10; /* fallthrough */ // bump up to 0x4n
case 0x18: case 0x19: case 0x1A: case 0x1B: case 0x1C: case 0x1D: case 0x1F: // RR A
case 0x08: case 0x09: case 0x0A: case 0x0B: case 0x0C: case 0x0D: case 0x0F: // RRC A
case 0x28: case 0x29: case 0x2A: case 0x2B: case 0x2C: case 0x2D: case 0x2F: // SRA A
op = R8( data & 7 );
goto rr_comm;
} // CB op
assert( false ); // unhandled CB op
// fallthrough
case 0x07: // RLCA
case 0x17: // RLA
data = op;
op = rg.a;
rl_comm:
op <<= 1;
op |= ((data & flags) >> 4) & 1; // RL and carry is set
flags = (op >> 4) & c_flag; // C = bit shifted out
if ( data < 0x10 ) // RLC
op |= op >> 8;
// SLA doesn't fill lower bit
goto shift_comm;
case 0x0F: // RRCA
case 0x1F: // RRA
data = op;
op = rg.a;
rr_comm:
op |= (data & flags) << 4; // RR and carry is set
flags = (op << 4) & c_flag; // C = bit shifted out
if ( data < 0x10 ) // RRC
op |= op << 8;
op >>= 1;
if ( data & 0x20 ) // SRA propagates sign bit
op |= (op << 1) & 0x80;
shift_comm:
data &= 7;
if ( !(op & 0xFF) )
flags |= z_flag;
if ( data == 6 )
goto write_hl_op_ff;
R8( data ) = op;
goto loop;
// Load
case 0x70: // LD (HL),B
case 0x71: // LD (HL),C
case 0x72: // LD (HL),D
case 0x73: // LD (HL),E
case 0x74: // LD (HL),H
case 0x75: // LD (HL),L
case 0x77: // LD (HL),A
op = R8( op & 7 );
write_hl_op_ff:
WRITE( rp.hl, op & 0xFF );
goto loop;
case 0x41: case 0x42: case 0x43: case 0x44: case 0x45: case 0x47: // LD r,r
case 0x48: case 0x4A: case 0x4B: case 0x4C: case 0x4D: case 0x4F:
case 0x50: case 0x51: case 0x53: case 0x54: case 0x55: case 0x57:
case 0x58: case 0x59: case 0x5A: case 0x5C: case 0x5D: case 0x5F:
case 0x60: case 0x61: case 0x62: case 0x63: case 0x65: case 0x67:
case 0x68: case 0x69: case 0x6A: case 0x6B: case 0x6C: case 0x6F:
case 0x78: case 0x79: case 0x7A: case 0x7B: case 0x7C: case 0x7D:
R8( (op >> 3) & 7 ) = R8( op & 7 );
goto loop;
case 0x08: // LD IND16,SP
data = GET_ADDR();
pc += 2;
WRITE( data, sp&0xFF );
data++;
WRITE( data, sp >> 8 );
goto loop;
case 0xF9: // LD SP,HL
sp = rp.hl;
goto loop;
case 0x31: // LD SP,IMM
sp = GET_ADDR();
pc += 2;
goto loop;
case 0x01: // LD BC,IMM
case 0x11: // LD DE,IMM
r16 [op >> 4] = GET_ADDR();
pc += 2;
goto loop;
{
unsigned temp;
case 0xE0: // LD (0xFF00+imm),A
temp = data | 0xFF00;
pc++;
goto write_data_rg_a;
case 0xE2: // LD (0xFF00+C),A
temp = rg.c | 0xFF00;
goto write_data_rg_a;
case 0x32: // LD (HL-),A
temp = rp.hl;
rp.hl = temp - 1;
goto write_data_rg_a;
case 0x02: // LD (BC),A
temp = rp.bc;
goto write_data_rg_a;
case 0x12: // LD (DE),A
temp = rp.de;
goto write_data_rg_a;
case 0x22: // LD (HL+),A
temp = rp.hl;
rp.hl = temp + 1;
goto write_data_rg_a;
case 0xEA: // LD IND16,A (common)
temp = GET_ADDR();
pc += 2;
write_data_rg_a:
WRITE( temp, rg.a );
goto loop;
}
case 0x06: // LD B,IMM
rg.b = data;
pc++;
goto loop;
case 0x0E: // LD C,IMM
rg.c = data;
pc++;
goto loop;
case 0x16: // LD D,IMM
rg.d = data;
pc++;
goto loop;
case 0x1E: // LD E,IMM
rg.e = data;
pc++;
goto loop;
case 0x26: // LD H,IMM
rg.h = data;
pc++;
goto loop;
case 0x2E: // LD L,IMM
rg.l = data;
pc++;
goto loop;
case 0x36: // LD (HL),IMM
WRITE( rp.hl, data );
pc++;
goto loop;
case 0x3E: // LD A,IMM
rg.a = data;
pc++;
goto loop;
// Increment/Decrement
case 0x03: // INC BC
case 0x13: // INC DE
case 0x23: // INC HL
r16 [op >> 4]++;
goto loop;
case 0x33: // INC SP
sp = (sp + 1) & 0xFFFF;
goto loop;
case 0x0B: // DEC BC
case 0x1B: // DEC DE
case 0x2B: // DEC HL
r16 [op >> 4]--;
goto loop;
case 0x3B: // DEC SP
sp = (sp - 1) & 0xFFFF;
goto loop;
case 0x34: // INC (HL)
op = rp.hl;
data = READ( op );
data++;
WRITE( op, data & 0xFF );
goto inc_comm;
case 0x04: // INC B
case 0x0C: // INC C (common)
case 0x14: // INC D
case 0x1C: // INC E
case 0x24: // INC H
case 0x2C: // INC L
case 0x3C: // INC A
op = (op >> 3) & 7;
R8( op ) = data = R8( op ) + 1;
inc_comm:
flags = (flags & c_flag) | (((data & 15) - 1) & h_flag) | ((data >> 1) & z_flag);
goto loop;
case 0x35: // DEC (HL)
op = rp.hl;
data = READ( op );
data--;
WRITE( op, data & 0xFF );
goto dec_comm;
case 0x05: // DEC B
case 0x0D: // DEC C
case 0x15: // DEC D
case 0x1D: // DEC E
case 0x25: // DEC H
case 0x2D: // DEC L
case 0x3D: // DEC A
op = (op >> 3) & 7;
data = R8( op ) - 1;
R8( op ) = data;
dec_comm:
flags = (flags & c_flag) | n_flag | (((data & 15) + 0x31) & h_flag);
if ( data & 0xFF )
goto loop;
flags |= z_flag;
goto loop;
// Add 16-bit
{
blargg_ulong temp; // need more than 16 bits for carry
unsigned prev;
case 0xF8: // LD HL,SP+imm
temp = int8_t (data); // sign-extend to 16 bits
pc++;
flags = 0;
temp += sp;
prev = sp;
goto add_16_hl;
case 0xE8: // ADD SP,IMM
temp = int8_t (data); // sign-extend to 16 bits
pc++;
flags = 0;
temp += sp;
prev = sp;
sp = temp & 0xFFFF;
goto add_16_comm;
case 0x39: // ADD HL,SP
temp = sp;
goto add_hl_comm;
case 0x09: // ADD HL,BC
case 0x19: // ADD HL,DE
case 0x29: // ADD HL,HL
temp = r16 [op >> 4];
add_hl_comm:
prev = rp.hl;
temp += prev;
flags &= z_flag;
add_16_hl:
rp.hl = temp;
add_16_comm:
flags |= (temp >> 12) & c_flag;
flags |= (((temp & 0x0FFF) - (prev & 0x0FFF)) >> 7) & h_flag;
goto loop;
}
case 0x86: // ADD (HL)
data = READ( rp.hl );
goto add_comm;
case 0x80: // ADD B
case 0x81: // ADD C
case 0x82: // ADD D
case 0x83: // ADD E
case 0x84: // ADD H
case 0x85: // ADD L
case 0x87: // ADD A
data = R8( op & 7 );
goto add_comm;
case 0xC6: // ADD IMM
pc++;
add_comm:
flags = rg.a;
data += flags;
flags = ((data & 15) - (flags & 15)) & h_flag;
flags |= (data >> 4) & c_flag;
rg.a = data;
if ( data & 0xFF )
goto loop;
flags |= z_flag;
goto loop;
// Add/Subtract
case 0x8E: // ADC (HL)
data = READ( rp.hl );
goto adc_comm;
case 0x88: // ADC B
case 0x89: // ADC C
case 0x8A: // ADC D
case 0x8B: // ADC E
case 0x8C: // ADC H
case 0x8D: // ADC L
case 0x8F: // ADC A
data = R8( op & 7 );
goto adc_comm;
case 0xCE: // ADC IMM
pc++;
adc_comm:
data += (flags >> 4) & 1;
data &= 0xFF; // to do: does carry get set when sum + carry = 0x100?
goto add_comm;
case 0x96: // SUB (HL)
data = READ( rp.hl );
goto sub_comm;
case 0x90: // SUB B
case 0x91: // SUB C
case 0x92: // SUB D
case 0x93: // SUB E
case 0x94: // SUB H
case 0x95: // SUB L
case 0x97: // SUB A
data = R8( op & 7 );
goto sub_comm;
case 0xD6: // SUB IMM
pc++;
sub_comm:
op = rg.a;
data = op - data;
rg.a = data;
goto sub_set_flags;
case 0x9E: // SBC (HL)
data = READ( rp.hl );
goto sbc_comm;
case 0x98: // SBC B
case 0x99: // SBC C
case 0x9A: // SBC D
case 0x9B: // SBC E
case 0x9C: // SBC H
case 0x9D: // SBC L
case 0x9F: // SBC A
data = R8( op & 7 );
goto sbc_comm;
case 0xDE: // SBC IMM
pc++;
sbc_comm:
data += (flags >> 4) & 1;
data &= 0xFF; // to do: does carry get set when sum + carry = 0x100?
goto sub_comm;
// Logical
case 0xA0: // AND B
case 0xA1: // AND C
case 0xA2: // AND D
case 0xA3: // AND E
case 0xA4: // AND H
case 0xA5: // AND L
data = R8( op & 7 );
goto and_comm;
case 0xA6: // AND (HL)
data = READ( rp.hl );
pc--; // FALLTHRU
case 0xE6: // AND IMM
pc++;
and_comm:
rg.a &= data; // FALLTHRU
case 0xA7: // AND A
flags = h_flag | (((rg.a - 1) >> 1) & z_flag);
goto loop;
case 0xB0: // OR B
case 0xB1: // OR C
case 0xB2: // OR D
case 0xB3: // OR E
case 0xB4: // OR H
case 0xB5: // OR L
data = R8( op & 7 );
goto or_comm;
case 0xB6: // OR (HL)
data = READ( rp.hl );
pc--; // FALLTHRU
case 0xF6: // OR IMM
pc++;
or_comm:
rg.a |= data; // FALLTHRU
case 0xB7: // OR A
flags = ((rg.a - 1) >> 1) & z_flag;
goto loop;
case 0xA8: // XOR B
case 0xA9: // XOR C
case 0xAA: // XOR D
case 0xAB: // XOR E
case 0xAC: // XOR H
case 0xAD: // XOR L
data = R8( op & 7 );
goto xor_comm;
case 0xAE: // XOR (HL)
data = READ( rp.hl );
pc--; // FALLTHRU
case 0xEE: // XOR IMM
pc++;
xor_comm:
data ^= rg.a;
rg.a = data;
data--;
flags = (data >> 1) & z_flag;
goto loop;
case 0xAF: // XOR A
rg.a = 0;
flags = z_flag;
goto loop;
// Stack
case 0xF1: // POP FA
case 0xC1: // POP BC
case 0xD1: // POP DE
case 0xE1: // POP HL (common)
data = READ( sp );
r16 [(op >> 4) & 3] = data + 0x100 * READ( sp + 1 );
sp = (sp + 2) & 0xFFFF;
if ( op != 0xF1 )
goto loop;
flags = rg.flags & 0xF0;
goto loop;
case 0xC5: // PUSH BC
data = rp.bc;
goto push;
case 0xD5: // PUSH DE
data = rp.de;
goto push;
case 0xE5: // PUSH HL
data = rp.hl;
goto push;
case 0xF5: // PUSH FA
data = (flags << 8) | rg.a;
goto push;
// Flow control
case 0xFF:
if ( pc == idle_addr + 1 )
goto stop;
// FALLTHRU
case 0xC7: case 0xCF: case 0xD7: case 0xDF: // RST
case 0xE7: case 0xEF: case 0xF7:
data = pc;
pc = (op & 0x38) + rst_base;
goto push;
case 0xCC: // CZ
pc += 2;
if ( flags & z_flag )
goto call;
goto loop;
case 0xD4: // CNC
pc += 2;
if ( !(flags & c_flag) )
goto call;
goto loop;
case 0xDC: // CC
pc += 2;
if ( flags & c_flag )
goto call;
goto loop;
case 0xD9: // RETI
//interrupts_enabled = 1;
goto ret;
case 0xC0: // RZ
if ( !(flags & z_flag) )
goto ret;
goto loop;
case 0xD0: // RNC
if ( !(flags & c_flag) )
goto ret;
goto loop;
case 0xD8: // RC
if ( flags & c_flag )
goto ret;
goto loop;
case 0x18: // JR
BRANCH( true )
case 0x30: // JR NC
BRANCH( !(flags & c_flag) )
case 0x38: // JR C
BRANCH( flags & c_flag )
case 0xE9: // JP_HL
pc = rp.hl;
goto loop;
case 0xC3: // JP (next-most-common)
pc = GET_ADDR();
goto loop;
case 0xC2: // JP NZ
pc += 2;
if ( !(flags & z_flag) )
goto jp_taken;
goto loop;
case 0xCA: // JP Z (most common)
pc += 2;
if ( !(flags & z_flag) )
goto loop;
jp_taken:
pc -= 2;
pc = GET_ADDR();
goto loop;
case 0xD2: // JP NC
pc += 2;
if ( !(flags & c_flag) )
goto jp_taken;
goto loop;
case 0xDA: // JP C
pc += 2;