#include <cstdio>

 #include <cstring>

 

 #include "gbGlobals.h"

 

 typedef struct

 {

 	u8    mask;

 	u8    value;

 	char *mnen;

 } GBOPCODE;

 

 static char *registers[] =

 { "B", "C", "D", "E", "H", "L", "(HL)", "A" };

 

 static char *registers16[] =

 { "BC", "DE", "HL", "SP", // for some operations

   "BC", "DE", "HL", "AF" };   // for push/pop

 

 static char *cond[] =

 { "NZ", "Z", "NC", "C" };

 

 static char hexDigits[16] = {

 	'0', '1', '2', '3', '4', '5', '6', '7',

 	'8', '9', 'A', 'B', 'C', 'D', 'E', 'F'

 };

 

 static GBOPCODE opcodes[] = {

 	{ 0xff, 0x00, "NOP"            },

 	{ 0xcf, 0x01, "LD %R4,%W"      },

 	{ 0xff, 0x02, "LD (BC),A"      },

 	{ 0xcf, 0x03, "INC %R4"        },

 	{ 0xc7, 0x04, "INC %r3"        },

 	{ 0xc7, 0x05, "DEC %r3"        },

 	{ 0xc7, 0x06, "LD %r3,%B"      },

 	{ 0xff, 0x07, "RLCA"           },

 	{ 0xff, 0x08, "LD (%W),SP"     },

 	{ 0xcf, 0x09, "ADD HL,%R4"     },

 	{ 0xff, 0x0a, "LD A,(BC)"      },

 	{ 0xcf, 0x0b, "DEC %R4"        },

 	{ 0xff, 0x0f, "RRCA"           },

 	{ 0xff, 0x10, "STOP"           },

 	{ 0xff, 0x12, "LD (DE),A"      },

 	{ 0xff, 0x17, "RLA"            },

 	{ 0xff, 0x18, "JR %d"          },

 	{ 0xff, 0x1a, "LD A,(DE)"      },

 	{ 0xff, 0x1f, "RRA"            },

 	{ 0xe7, 0x20, "JR %c3,%d"      },

 	{ 0xff, 0x22, "LDI (HL),A"     },

 	{ 0xff, 0x27, "DAA"            },

 	{ 0xff, 0x2a, "LDI A,(HL)"     },

 	{ 0xff, 0x2f, "CPL"            },

 	{ 0xff, 0x32, "LDD (HL),A"     },

 	{ 0xff, 0x37, "SCF"            },

 	{ 0xff, 0x3a, "LDD A,(HL)"     },

 	{ 0xff, 0x3f, "CCF"            },

 	{ 0xff, 0x76, "HALT"           },

 	{ 0xc0, 0x40, "LD %r3,%r0"     },

 	{ 0xf8, 0x80, "ADD A,%r0"      },

 	{ 0xf8, 0x88, "ADC A,%r0"      },

 	{ 0xf8, 0x90, "SUB %r0"        },

 	{ 0xf8, 0x98, "SBC A,%r0"      },

 	{ 0xf8, 0xa0, "AND %r0"        },

 	{ 0xf8, 0xa8, "XOR %r0"        },

 	{ 0xf8, 0xb0, "OR %r0"         },

 	{ 0xf8, 0xb8, "CP %r0"         },

 	{ 0xe7, 0xc0, "RET %c3"        },

 	{ 0xcf, 0xc1, "POP %t4"        },

 	{ 0xe7, 0xc2, "JP %c3,%W"      },

 	{ 0xff, 0xc3, "JP %W"          },

 	{ 0xe7, 0xc4, "CALL %c3,%W"    },

 	{ 0xcf, 0xc5, "PUSH %t4"       },

 	{ 0xff, 0xc6, "ADD A,%B"       },

 	{ 0xc7, 0xc7, "RST %P"         },

 	{ 0xff, 0xc9, "RET"            },

 	{ 0xff, 0xcd, "CALL %W"        },

 	{ 0xff, 0xce, "ADC %B"         },

 	{ 0xff, 0xd6, "SUB %B"         },

 	{ 0xff, 0xd9, "RETI"           },

 	{ 0xff, 0xde, "SBC %B"         },

 	{ 0xff, 0xe0, "LD (FF%B),A"    },

 	{ 0xff, 0xe2, "LD (FF00h+C),A" },

 	{ 0xff, 0xe6, "AND %B"         },

 	{ 0xff, 0xe8, "ADD SP,%D"      },

 	{ 0xff, 0xe9, "LD PC,HL"       },

 	{ 0xff, 0xea, "LD (%W),A"      },

 	{ 0xff, 0xee, "XOR %B"         },

 	{ 0xff, 0xf0, "LD A,(FF%B)"    },

 	{ 0xff, 0xf2, "LD A,(FF00h+C)" },

 	{ 0xff, 0xf3, "DI"             },

 	{ 0xff, 0xf6, "OR %B"          },

 	{ 0xff, 0xf8, "LD HL,SP%D"     },

 	{ 0xff, 0xf9, "LD SP,HL"       },

 	{ 0xff, 0xfa, "LD A,(%W)"      },

 	{ 0xff, 0xfb, "EI"             },

 	{ 0xff, 0xfe, "CP %B"          },

 	{ 0x00, 0x00, "DB %B"          }

 };

 

 static GBOPCODE cbOpcodes[] = {

 	{ 0xf8, 0x00, "RLC %r0"    },

 	{ 0xf8, 0x08, "RRC %r0"    },

 	{ 0xf8, 0x10, "RL %r0"     },

 	{ 0xf8, 0x18, "RR %r0"     },

 	{ 0xf8, 0x20, "SLA %r0"    },

 	{ 0xf8, 0x28, "SRA %r0"    },

 	{ 0xf8, 0x30, "SWAP %r0"   },

 	{ 0xf8, 0x38, "SRL %r0"    },

 	{ 0xc0, 0x40, "BIT %b,%r0" },

 	{ 0xc0, 0x80, "RES %b,%r0" },

 	{ 0xc0, 0xc0, "SET %b,%r0" },

 	{ 0x00, 0x00, "DB CBh,%B"  }

 };

 

 static char *addHex(char *p, u8 value)

 {

 	*p++ = hexDigits[value >> 4];

 	*p++ = hexDigits[value & 15];

 	return p;

 }

 

 static char *addHex16(char *p, u16 value)

 {

 	p = addHex(p, value>>8);

 	return addHex(p, value & 255);

 }

 

 static char *addStr(char *p, char *s)

 {

 	while (*s)

 	{

 		*p++ = *s++;

 	}

 	return p;

 }

 

 int gbDis(char *buffer, u16 address)

 {

 	char *p     = buffer;

 	int   instr = 1;

 	u16   addr  = address;

 	sprintf(p, "%04x        ", address);

 	p += 12;

 

 	u8 opcode = gbReadMemoryQuick(address);

 	address++;

 	char *    mnen;

 	GBOPCODE *op;

 	if (opcode == 0xcb)

 	{

 		opcode = gbReadMemoryQuick(address);

 		address++;

 		instr++;

 		op = cbOpcodes;

 	}

 	else

 	{

 		op = opcodes;

 	}

 	while (op->value != (opcode & op->mask))

 		op++;

 	mnen = op->mnen;

 

 	u8  b0, b1;

 	s8  disp;

 	int shift;

 

 	while (*mnen)

 	{

 		if (*mnen == '%')

 		{

 			mnen++;

 			switch (*mnen++)

 			{

 			case 'W':

 				b0 = gbReadMemoryQuick(address);

 				address++;

 				b1 = gbReadMemoryQuick(address);

 				address++;

 				p      = addHex16(p, b0|b1<<8);

 				instr += 2;

 				*p++   = 'h';

 				break;

 			case 'B':

 				p    = addHex(p, gbReadMemoryQuick(address));

 				*p++ = 'h';

 				address++;

 				instr++;

 				break;

 			case 'D':

 				disp = gbReadMemoryQuick(address);

 				if (disp >= 0)

 					*p++ = '+';

 				p += sprintf(p, "%d", disp);

 				instr++;

 				break;

 			case 'd':

 				disp = gbReadMemoryQuick(address);

 				address++;

 				p    = addHex16(p, address+disp);

 				*p++ = 'h';

 				instr++;

 				break;

 			case 'b':

 				// kind of a hack, but it works :-)

 				*p++ = hexDigits[(opcode >> 3) & 7];

 				break;

 			case 'r':

 				shift = *mnen++ - '0';

 				p     = addStr(p, registers[(opcode >> shift) & 7]);

 				break;

 			case 'R':

 				shift = *mnen++ - '0';

 				p     = addStr(p, registers16[(opcode >> shift) & 3]);

 				break;

 			case 't':

 				shift = *mnen++ - '0';

 				p     = addStr(p, registers16[4+((opcode >> shift) & 3)]);

 				break;

 			case 'P':

 				p = addHex(p, ((opcode >> 3) & 7) * 8);

 				break;

 			case 'c':

 				shift = *mnen++ - '0';

 				p     = addStr(p, cond[(opcode >> shift) & 3]);

 				break;

 			}

 		}

 		else

 			*p++ = *mnen++;

 	}

 	for (int i = 0; i < instr; i++)

 	{

 		u16 a = addr + i;

 		addHex(buffer+5+i*2, gbReadMemoryQuick(a));

 	}

 	*p = 0;

 	return instr;

 }