#include "gen_x86.h"
#include "68kinst.h"
#include <stddef.h>
#include <stdio.h>

#define REX_RM_FIELD 0x1
#define REX_SIB_FIELD 0x2
#define REX_REG_FIELD 0x4
#define REX_QUAD 0x8

#define OP_ADD 0x00
#define OP_OR  0x08
#define PRE_2BYTE 0x0F
#define OP_ADC 0x10
#define OP_SBB 0x18
#define OP_AND 0x20
#define OP_SUB 0x28
#define OP_XOR 0x30
#define OP_CMP 0x38
#define PRE_REX 0x40
#define OP_PUSH 0x50
#define OP_POP 0x58
#define PRE_SIZE 0x66
#define OP_JCC 0x70
#define OP_IMMED_ARITH 0x80
#define OP_MOV 0x88
#define OP_PUSHF 0x9C
#define OP_POPF 0x9D
#define OP_MOV_I8R 0xB0
#define OP_MOV_IR 0xB8
#define OP_RETN 0xC3
#define OP_MOV_IEA 0xC6
#define OP_CALL 0xE8
#define OP_CALL_EA 0xFF

#define OP2_JCC 0x80
#define OP2_SETCC 0x90

#define OP_EX_ADDI 0x0
#define OP_EX_ORI  0x1
#define OP_EX_ADCI 0x2
#define OP_EX_SBBI 0x3
#define OP_EX_ANDI 0x4
#define OP_EX_SUBI 0x5
#define OP_EX_XORI 0x6
#define OP_EX_CMPI 0x7

#define BIT_IMMED_RAX 0x4
#define BIT_DIR 0x2
#define BIT_SIZE 0x1

#define M68K_N_REG RBX
#define M68K_V_REG BH
#define M68K_Z_REG RDX
#define M68K_C_REG DH

#define M68K_SCRATCH RCX

enum {
	X86_RAX = 0,
	X86_RCX,
	X86_RDX,
	X86_RBX,
	X86_RSP,
	X86_RBP,
	X86_RSI,
	X86_RDI,
	X86_AH=4,
	X86_CH,
	X86_DH,
	X86_BH,
	X86_R8=0,
	X86_R9,
	X86_R10,
	X86_R11,
	X86_R12,
	X86_R13,
	X86_R14,
	X86_R15
} x86_regs_enc;

enum {
	MODE_REG_INDIRECT = 0,
	MODE_REG_DISPLACE8 = 0x40,
	MODE_REG_DIPSLACE32 = 0x80,
	MODE_REG_DIRECT = 0xC0
} x86_modes;

uint8_t * x86_rr_sizedir(uint8_t * out, uint8_t opcode, uint8_t src, uint8_t dst, uint8_t size)
{
	//TODO: Deal with the fact that AH, BH, CH and DH can only be in the R/M param when there's a REX prefix
	uint8_t tmp;
	if (size == SZ_W) {
		*(out++) = PRE_SIZE;
	}
	if (size == SZ_B && dst >= RSP && dst <= RDI) {
		opcode |= BIT_DIR;
		tmp = dst;
		dst = src;
		src = dst;
	}
	if (size == SZ_Q || src >= R8 || dst >= R8 || (size == SZ_B && src >= RSP && src <= RDI)) {
		*out = PRE_REX;
		if (size == SZ_Q) {
			*out |= REX_QUAD;
		}
		if (src >= R8) {
			*out |= REX_REG_FIELD;
			src -= (R8 - X86_R8);
		}
		if (dst >= R8) {
			*out |= REX_RM_FIELD;
			dst -= (R8 - X86_R8);
		}
		out++;
	}
	if (size == SZ_B) {
		if (src >= AH && src <= BH) {
			src -= (AH-X86_AH);
		}
		if (dst >= AH && dst <= BH) {
			dst -= (AH-X86_AH);
		}
	} else {
		opcode |= BIT_SIZE;
	}
	*(out++) = opcode;
	*(out++) = MODE_REG_DIRECT | dst | (src << 3);
	return out;
}

uint8_t * x86_rrdisp8_sizedir(uint8_t * out, uint8_t opcode, uint8_t reg, uint8_t base, int8_t disp, uint8_t size, uint8_t dir)
{
	//TODO: Deal with the fact that AH, BH, CH and DH can only be in the R/M param when there's a REX prefix
	uint8_t tmp;
	if (size == SZ_W) {
		*(out++) = PRE_SIZE;
	}
	if (size == SZ_Q || reg >= R8 || base >= R8 || (size == SZ_B && reg >= RSP && reg <= RDI)) {
		*out = PRE_REX;
		if (size == SZ_Q) {
			*out |= REX_QUAD;
		}
		if (reg >= R8) {
			*out |= REX_REG_FIELD;
			reg -= (R8 - X86_R8);
		}
		if (base >= R8) {
			*out |= REX_RM_FIELD;
			base -= (R8 - X86_R8);
		}
		out++;
	}
	if (size == SZ_B) {
		if (reg >= AH && reg <= BH) {
			reg -= (AH-X86_AH);
		}
	} else {
		opcode |= BIT_SIZE;
	}
	*(out++) = opcode | dir;
	*(out++) = MODE_REG_DISPLACE8 | base | (reg << 3);
	*(out++) = disp;
	return out;
}

uint8_t * x86_rrind_sizedir(uint8_t * out, uint8_t opcode, uint8_t reg, uint8_t base, uint8_t size, uint8_t dir)
{
	//TODO: Deal with the fact that AH, BH, CH and DH can only be in the R/M param when there's a REX prefix
	uint8_t tmp;
	if (size == SZ_W) {
		*(out++) = PRE_SIZE;
	}
	if (size == SZ_Q || reg >= R8 || base >= R8 || (size == SZ_B && reg >= RSP && reg <= RDI)) {
		*out = PRE_REX;
		if (size == SZ_Q) {
			*out |= REX_QUAD;
		}
		if (reg >= R8) {
			*out |= REX_REG_FIELD;
			reg -= (R8 - X86_R8);
		}
		if (base >= R8) {
			*out |= REX_RM_FIELD;
			base -= (R8 - X86_R8);
		}
		out++;
	}
	if (size == SZ_B) {
		if (reg >= AH && reg <= BH) {
			reg -= (AH-X86_AH);
		}
	} else {
		opcode |= BIT_SIZE;
	}
	*(out++) = opcode | dir;
	*(out++) = MODE_REG_INDIRECT | base | (reg << 3);
	return out;
}

uint8_t * x86_ir(uint8_t * out, uint8_t opcode, uint8_t op_ex, uint8_t al_opcode, int32_t val, uint8_t dst, uint8_t size)
{
	uint8_t sign_extend = 0;
	if ((size == SZ_D || size == SZ_Q) && val <= 0x7F && val >= -0x80) {
		sign_extend = 1;
		opcode |= BIT_DIR;
	}
	if (size == SZ_W) {
		*(out++) = PRE_SIZE;
	}
	if (dst == RAX && !sign_extend) {
		if (size != SZ_B) {
			al_opcode |= BIT_SIZE;
			if (size == SZ_Q) {
				*out = PRE_REX | REX_QUAD;
			}
		}
		*(out++) = al_opcode | BIT_IMMED_RAX;
	} else {
		if (size == SZ_Q || dst >= R8 || (size == SZ_B && dst >= RSP && dst <= RDI)) {
			*out = PRE_REX;
			if (size == SZ_Q) {
				*out |= REX_QUAD;
			}
			if (dst >= R8) {
				*out |= REX_RM_FIELD;
				dst -= (R8 - X86_R8);
			}
			out++;
		}
		if (dst >= AH && dst <= BH) {
			dst -= (AH-X86_AH);
		}
		if (size != SZ_B) {
			opcode |= BIT_SIZE;
		}
		*(out++) = opcode;
		*(out++) = MODE_REG_DIRECT | dst | (op_ex << 3);
	}
	*(out++) = val;
	if (size != SZ_B && !sign_extend) {
		val >>= 8;
		*(out++) = val;
		if (size != SZ_W) {
			val >>= 8;
			*(out++) = val;
			val >>= 8;
			*(out++) = val;
		}
	}
	return out;
}


uint8_t * add_rr(uint8_t * out, uint8_t src, uint8_t dst, uint8_t size)
{
	return x86_rr_sizedir(out, OP_ADD, src, dst, size);
}

uint8_t * add_ir(uint8_t * out, int32_t val, uint8_t dst, uint8_t size)
{
	return x86_ir(out, OP_IMMED_ARITH, OP_EX_ADDI, OP_ADD, val, dst, size);
}

uint8_t * or_rr(uint8_t * out, uint8_t src, uint8_t dst, uint8_t size)
{
	return x86_rr_sizedir(out, OP_OR, src, dst, size);
}
uint8_t * or_ir(uint8_t * out, int32_t val, uint8_t dst, uint8_t size)
{
	return x86_ir(out, OP_IMMED_ARITH, OP_EX_ORI, OP_OR, val, dst, size);
}

uint8_t * and_rr(uint8_t * out, uint8_t src, uint8_t dst, uint8_t size)
{
	return x86_rr_sizedir(out, OP_AND, src, dst, size);
}

uint8_t * and_ir(uint8_t * out, int32_t val, uint8_t dst, uint8_t size)
{
	return x86_ir(out, OP_IMMED_ARITH, OP_EX_ANDI, OP_AND, val, dst, size);
}

uint8_t * xor_rr(uint8_t * out, uint8_t src, uint8_t dst, uint8_t size)
{
	return x86_rr_sizedir(out, OP_XOR, src, dst, size);
}

uint8_t * xor_ir(uint8_t * out, int32_t val, uint8_t dst, uint8_t size)
{
	return x86_ir(out, OP_IMMED_ARITH, OP_EX_XORI, OP_XOR, val, dst, size);
}

uint8_t * sub_rr(uint8_t * out, uint8_t src, uint8_t dst, uint8_t size)
{
	return x86_rr_sizedir(out, OP_SUB, src, dst, size);
}

uint8_t * sub_ir(uint8_t * out, int32_t val, uint8_t dst, uint8_t size)
{
	return x86_ir(out, OP_IMMED_ARITH, OP_EX_SUBI, OP_SUB, val, dst, size);
}

uint8_t * cmp_rr(uint8_t * out, uint8_t src, uint8_t dst, uint8_t size)
{
	return x86_rr_sizedir(out, OP_CMP, src, dst, size);
}

uint8_t * cmp_ir(uint8_t * out, int32_t val, uint8_t dst, uint8_t size)
{
	return x86_ir(out, OP_IMMED_ARITH, OP_EX_CMPI, OP_CMP, val, dst, size);
}

uint8_t * mov_rr(uint8_t * out, uint8_t src, uint8_t dst, uint8_t size)
{
	return x86_rr_sizedir(out, OP_MOV, src, dst, size);
}

uint8_t * mov_rrdisp8(uint8_t * out, uint8_t src, uint8_t dst_base, int8_t disp, uint8_t size)
{
	return x86_rrdisp8_sizedir(out, OP_MOV, src, dst_base, disp, size, 0);
}

uint8_t * mov_rdisp8r(uint8_t * out, uint8_t src_base, int8_t disp, uint8_t dst, uint8_t size)
{
	return x86_rrdisp8_sizedir(out, OP_MOV, dst, src_base, disp, size, BIT_DIR);
}

uint8_t * mov_rrind(uint8_t * out, uint8_t src, uint8_t dst, uint8_t size)
{
	return x86_rrind_sizedir(out, OP_MOV, src, dst, size, 0);
}

uint8_t * mov_rindr(uint8_t * out, uint8_t src, uint8_t dst, uint8_t size)
{
	return x86_rrind_sizedir(out, OP_MOV, dst, src, size, BIT_DIR);
}

uint8_t * mov_ir(uint8_t * out, int64_t val, uint8_t dst, uint8_t size)
{	
	uint8_t sign_extend = 0;
	if (size == SZ_Q && val <= 0x7FFFFFFF && val >= -2147483648) {
		sign_extend = 1;
	}
	if (size == SZ_W) {
		*(out++) = PRE_SIZE;
	}
	if (size == SZ_Q || dst >= R8 || (size == SZ_B && dst >= RSP && dst <= RDI)) {
		*out = PRE_REX;
		if (size == SZ_Q) {
			*out |= REX_QUAD;
		}
		if (dst >= R8) {
			*out |= REX_RM_FIELD;
			dst -= (R8 - X86_R8);
		}
		out++;
	}
	if (dst >= AH && dst <= BH) {
		dst -= (AH-X86_AH);
	}
	if (size == SZ_B) {
		*(out++) = OP_MOV_I8R;
	} else if (size == SZ_Q && sign_extend) {
		*(out++) = OP_MOV_IEA | BIT_SIZE;
		*(out++) = MODE_REG_DIRECT | dst;
	} else {
		*(out++) = OP_MOV_IR;
	}
	*(out++) = val;
	if (size != SZ_B) {
		val >>= 8;
		*(out++) = val;
		if (size != SZ_W) {
			val >>= 8;
			*(out++) = val;
			val >>= 8;
			*(out++) = val;
			if (size == SZ_Q && !sign_extend) {
				val >>= 8;
				*(out++) = val;
				val >>= 8;
				*(out++) = val;
				val >>= 8;
				*(out++) = val;
				val >>= 8;
				*(out++) = val;
			}
		}
	}
	return out;
}

uint8_t * pushf(uint8_t * out)
{
	*(out++) = OP_PUSHF;
	return out;
}

uint8_t * popf(uint8_t * out)
{
	*(out++) = OP_POPF;
	return out;
}

uint8_t * push_r(uint8_t * out, uint8_t reg)
{
	if (reg >= R8) {
		*(out++) = PRE_REX | REX_RM_FIELD;
		reg -= R8 - X86_R8;
	}
	*(out++) = OP_PUSH | reg;
	return out;
}

uint8_t * pop_r(uint8_t * out, uint8_t reg)
{
	if (reg >= R8) {
		*(out++) = PRE_REX | REX_RM_FIELD;
		reg -= R8 - X86_R8;
	}
	*(out++) = OP_POP | reg;
	return out;
}

uint8_t * setcc_r(uint8_t * out, uint8_t cc, uint8_t dst)
{
	if (dst >= R8) {
		*(out++) = PRE_REX | REX_RM_FIELD;
		dst -= R8 - X86_R8;
	} else if (dst >= RSP && dst <= RDI) {
		*(out++) = PRE_REX;
	} else if (dst >= AH && dst <= BH) {
		dst -= AH - X86_AH;
	}
	*(out++) = PRE_2BYTE;
	*(out++) = OP2_SETCC | cc;
	*(out++) = MODE_REG_DIRECT | dst;
	return out;
}

uint8_t * setcc_rind(uint8_t * out, uint8_t cc, uint8_t dst)
{
	if (dst >= R8) {
		*(out++) = PRE_REX | REX_RM_FIELD;
		dst -= R8 - X86_R8;
	}
	*(out++) = PRE_2BYTE;
	*(out++) = OP2_SETCC | cc;
	*(out++) = MODE_REG_INDIRECT | dst;
	return out;
}

uint8_t * jcc(uint8_t * out, uint8_t cc, int32_t disp)
{
	if (disp <= 0x7F && disp >= -0x80) {
		*(out++) = OP_JCC | cc;
		*(out++) = disp;
	} else {
		*(out++) = PRE_2BYTE;
		*(out++) = OP2_JCC | cc;
		*(out++) = disp;
		disp >>= 8;
		*(out++) = disp;
		disp >>= 8;
		*(out++) = disp;
		disp >>= 8;
		*(out++) = disp;
	}
	return out;
}

uint8_t * call(uint8_t * out, uint8_t * fun)
{
	ptrdiff_t disp = fun-(out+5);
	if (disp <= 0x7FFFFFFF && disp >= -2147483648) {
		*(out++) = OP_CALL;
		*(out++) = disp;
		disp >>= 8;
		*(out++) = disp;
		disp >>= 8;
		*(out++) = disp;
		disp >>= 8;
		*(out++) = disp;
	} else {
		//TODO: Implement far call
		printf("%p - %p = %ld, %d, %d, %d\n", fun, out + 5, disp, disp <= 0x7FFFFFFF, disp >= (-2147483648), -2147483648);
		return NULL;
	}
	return out;
}

uint8_t * retn(uint8_t * out)
{
	*(out++) = OP_RETN;
	return out;
}