#include "assembler.h"

#include <stdlib.h>

#define REGULAR_BEGIN   (ADD)
#define REGULAR_END     (CMP)
#define IRREGULAR_BEGIN (INC)
#define IRREGULAR_END   (IDIV)
#define SPECIAL_1_BEGIN (NOP)
#define SPECIAL_1_END   (PUSHF)
#define SPECIAL_2_BEGIN (SYSCALL)
#define SPECIAL_2_END   (FCOS)
#define JUMP_IF_BEGIN   (JO)
#define JUMP_IF_END     (JG)
#define MOVE_IF_BEGIN   (CMOVO)
#define MOVE_IF_END     (CMOVG)
#define FLOAT_BEGIN     (FADD)
#define FLOAT_END       (FDIVR)

static int assemble_clean_up_queued = 0;

static unsigned int   empty_count = 1;
static unsigned int   empty_holes = 1;
static unsigned int * empty_array = NULL;
static unsigned int * empty_imbue = NULL;
static unsigned int * empty_store = NULL;

static void replace (unsigned char * destination, unsigned char * source, unsigned long size) {
	for (--size; size != (unsigned long) -1; --size) {
		destination  [size] = source  [size];
	}
}

static void inset (int when, unsigned int data) {
	text_sector_byte [text_sector_size] = (unsigned char) data;

	text_sector_size += (unsigned int) when;
}

static void inset_immediate (int when, unsigned int size, unsigned int data) {
	inset ((when),                  (data >>  0) & 0xff);
	inset ((when) && (size >= D16), (data >>  8) & 0xff);
	inset ((when) && (size >= D32), (data >> 16) & 0xff);
	inset ((when) && (size >= D32), (data >> 24) & 0xff);
}

static void inset_memory (int when, unsigned int size, unsigned int data, unsigned int base) {
	empty_array [empty_holes] = text_sector_size;
	empty_imbue [empty_holes] = data;

	empty_holes += (unsigned int) when;

	inset_immediate (when, size, base);
}

static unsigned int store_relative (unsigned int * array) {
	unsigned int relative = array [1];

	empty_array [empty_holes] = text_sector_size;
	empty_imbue [empty_holes] = relative;

	++empty_holes;

	return (1);
}

static unsigned int store_memory (unsigned int * array) {
	unsigned int memory = array [1];

	empty_store [memory] = text_sector_size;

	++empty_count;

	return (1);
}

static unsigned int store_immediate (unsigned int * array) {
	unsigned int index  = 0,
	             size   = array [1],
	             amount = array [2];

	for (index = 0; index < amount; ++index) {
		inset_immediate (1, size, array [3 + index]);
	}

	return (amount + 2);
}

static int front (unsigned int data) {
	return ((data >= GR4) && (data <= GR7));
}

static int lower (unsigned int data) {
	return (data <= GR7);
}

static int upper (unsigned int data) {
	return ((data >= GR8) && (data <= GR15));
}

static int far (unsigned int label) {
	return (label && 1);
}

static int near (unsigned int label) {
	return (label && 0);
}

static void short_prefix (unsigned int size) {
	inset (size == D16, 0x66);
}

static void long_prefix (unsigned int size, unsigned int to, unsigned int destination, unsigned int from, unsigned int source) {
	unsigned int to_upper   = (to   == REG) && (upper (destination));
	unsigned int from_upper = (from == REG) && (upper (source));

	inset ((size == D64) || (to_upper) || (from_upper), 0x40 + 0x01 * to_upper + 0x04 * from_upper + 0x08 * (size == D64));
}

static void modify_registers (unsigned int to, unsigned int destination, unsigned int from, unsigned int source) {
	inset ((to == REG) && (from == REG), 0xc0 + 0x01 * (destination & 0x07) + 0x08 * (source & 0x07));
}

static void modify_memory (unsigned int operation, unsigned int to, unsigned int from) {
	inset (((to == MEM) && (from == REG)) || ((to == REG) && (from == MEM)), 0x05 + 0x08 * operation * ((to == MEM) && (from == IMM)));
}

// REFACTORING IN PROGRESS
static unsigned int build_regular (unsigned int * array) {
	unsigned int operation   = array [0],
	             size        = array [1],
	             to          = array [2],
	             destination = array [3],
	             from        = array [4],
	             source      = array [5];

	short_prefix (size);

	long_prefix (size, to, destination, from, source);

	inset ((size == D8) && (to == REG) && ((from == REG) || (from == IMM)) && (( (front (destination) && lower (source)) || (lower (destination) && front (source))) || ((to == REG) && (from == IMM) && front (destination))), 0x40);

	inset ((from == IMM) && (to == REG), 0x81 - 0x01 * (size == D8));

	inset ((from == IMM) && (to == REG) && (destination == 0), 0x05 + 0x08 * (operation & 0x07) - 0x01 * (size == D8));

	inset (! ((from == IMM) && (to == REG) && (destination == 0)), (destination & 0x07) * ((to == REG) && (from == IMM)) + 0x08 * (operation - REGULAR_BEGIN) + 0x01 * ((to == MEM) && (from == IMM) && (size == D8)) - 0x01 * ((to == REG) && (from == IMM) && (size != D8)) + 0x01 * (size != D8) + 0x02 * ((to == REG) && (from == MEM)) + 0x04 * ((to == MEM) && (from == IMM)) + 0xc0 * ((to == REG) && (from == IMM)));

	modify_registers (to, destination, from, source);

	modify_memory (destination, to, from);
	modify_memory (source,      to, from);

	inset_memory    ((to == REG) && (from == MEM), D32,  source, 0x1000 - (text_sector_size + 4));
	inset_immediate ((to == REG) && (from == IMM), size, source);
	inset_memory    ((to == MEM) && (from == REG), D32,  destination, 0x1000 - (text_sector_size + 4));
	inset_memory    ((to == MEM) && (from == IMM), D32,  destination, 0x1000 - (text_sector_size + 4));
	inset_immediate ((to == MEM) && (from == IMM), size, source);
	inset_memory    ((to == REG) && (from == REL), D32,  source, 0x4010b0 - (text_sector_size + 4));

	return (5);
}

static unsigned int build_irregular (unsigned int * array) {
	unsigned int operation   = array [0],
	             size        = array [1],
	             to          = array [2],
	             destination = array [3];

	short_prefix (size);

	long_prefix (size, to, destination, 0, 0);

	inset ((size == D8) && (to == REG) && front (destination), 0x40);

	inset (1, 0xf7 + 0x08 * ((operation == INC) || (operation == DEC)) - 0x01 * (size == D8));

	inset (to == REG, 0xc0 + 0x08 * (operation - IRREGULAR_BEGIN) + 0x01 * (destination & 0x07));
	inset (to == MEM, 0x05 + 0x08 * (operation - IRREGULAR_BEGIN));

	inset_memory (to == MEM, D32, destination, 0x1000 - (text_sector_size + 4));

	return (3);
}

static unsigned int build_special_1 (unsigned int * array) {
	unsigned int operation = array [0];

	const unsigned char data  [] = {
		0x90, 0xc3, 0xcb, 0xc9, 0x9d, 0x9c
	};

	inset (1, data [operation - SPECIAL_1_BEGIN]);

	return (0);
}

static unsigned int build_special_2 (unsigned int * array) {
	unsigned int operation = array [0];

	const unsigned short data  [] = {
		0x050f, 0xa20f, 0xd0d9, 0xe0d9, 0xe1d9, 0xe4d9, 0xe5d9, 0xe8d9,
		0xe9d9, 0xead9, 0xebd9, 0xecd9, 0xedd9, 0xeed9, 0xf0d9, 0xf1d9,
		0xf2d9, 0xf3d9, 0xf4d9, 0xf5d9, 0xf6d9, 0xf7d9, 0xf8d9, 0xf9d9,
		0xfad9, 0xfbd9, 0xfcd9, 0xfdd9, 0xfed9, 0xffd9
	};

	inset_immediate (1, D16, data [operation - SPECIAL_2_BEGIN]);

	return (0);
}

static unsigned int build_jump_if (unsigned int * array) {
	unsigned int operation = array [0],
	             size      = array [1],
	             location  = array [3];

	inset (far (location) && (size == D32), 0x0f);

	inset (far  (location), 0x80 + operation - JUMP_IF_BEGIN);
	inset (near (location), 0x70 + operation - JUMP_IF_BEGIN);

	inset_memory (1, D32, location, -(text_sector_size + 4));

	return (3);
}

static unsigned int build_move_if (unsigned int * array) {
	unsigned int operation   = array [0],
	             size        = array [1],
	             to          = array [2],
	             destination = array [3],
	             from        = array [4],
	             source      = array [5];

	short_prefix (size);

	long_prefix (size, to, destination, from, source);

	inset (1, 0x0f);
	inset (1, 0x40 + operation - MOVE_IF_BEGIN);

	modify_registers (to, destination, from, source);
	modify_memory (destination, to, from);

	return (5);
}

static unsigned int build_jump (unsigned int * array) {
	unsigned int size        = array [1],
	             to          = array [2],
	             destination = array [3];

	inset ((to == REG) && upper (destination), 0X41);

	inset (to == REL, 0xe9 + 0x02 * (size == D8));
	inset (to == REG, 0xff);
	inset (to == REG, 0xe0 + 0x01 * (destination & 0x07));
	inset (to == MEM, 0xff);
	inset (to == MEM, 0x25);

	inset_memory (to == REL, D32, destination, -(text_sector_size + 4));
	inset_memory (to == MEM, D32, destination, 0x4010b0);

	return (3);
}

static unsigned int build_move (unsigned int * array) {
	unsigned int size        = array [1],
	             to          = array [2],
	             destination = array [3],
	             from        = array [4],
	             source      = array [5];

	short_prefix (size);

	long_prefix (size, to, destination, from, source);

	inset ((to == REG) && (from == REG), 0x88 + 0x01 * (size != D8));
	inset ((to == REG) && (from == MEM), 0x8a + 0x01 * (size != D8));
	inset ((to == MEM) && (from == REG), 0x88 + 0x01 * (size != D8));

	modify_memory (destination, to, from);
	modify_memory (source,      to, from);

	modify_registers (to, destination, from, source);

	inset ((to == REG) && ((from == IMM) || (from == REL)), 0xb8 + 0x01 * (destination & 0x07));

	inset ((to == MEM) && (from == IMM), 0xc6 + 0x01 * (size != D8));
	inset ((to == MEM) && (from == IMM), 0x05);

	inset_memory    ((to == REG) && (from == MEM), D32,  source, 0x1000 - (text_sector_size + 4));
	inset_immediate ((to == REG) && (from == IMM), size, source);
	inset_memory    ((to == MEM) && (from == REG), D32,  destination, 0x1000 - (text_sector_size + 4));
	inset_memory    ((to == MEM) && (from == IMM), D32,  destination, 0x1000 - (text_sector_size + 4));
	inset_immediate ((to == MEM) && (from == IMM), size, source);
	inset_memory    ((to == REG) && (from == REL), D32,  source, 0x4010b0);

	inset_immediate ((to == REG) && (from == IMM) && (size == D64), D32, 0);

	return (5);
}

static unsigned int build_call (unsigned int * array) {
	unsigned int from   = array [1],
	             source = array [2];

	inset ((from == REG) && (upper (source)), 0x41);

	inset (from == REL, 0xe8);
	inset (from == REG, 0xff);

	inset_memory (from == REL, D32, source, -(text_sector_size + 4));

	inset (from == REG, (0xd0 + 0x01 * (source & 0x07)));

	return (2);
}

static unsigned int build_enter (unsigned int * array) {
	unsigned int dynamic_storage = array [1],
	             nesting_level   = array [2];

	inset (1, 0xc8);

	inset_immediate (1, D16, dynamic_storage);
	inset_immediate (1, D8,  nesting_level & 0x1f);

	return (2);
}

static unsigned int build_float (unsigned int * array) {
	unsigned int operation = array [0],
	             size      = array [1],
	             from      = array [2],
	             source    = array [3];

	inset (from == MEM, 0xd8 + 0x04 * (size == D64));

	modify_memory (operation, 0, from);

	inset_memory (from == MEM, size, source, 0);

	return (3);
}

static unsigned int build_in_out (unsigned int * array) {
	unsigned int move = array [0],
	             size = array [1],
	             type = array [2],
	             port = array [3];

	short_prefix (size);

	inset (1, 0xe4 + 0x01 * (size != D8) + 0x02 * (move != OUT) + 0x08 * (type == REG));

	inset_immediate (type == IMM, D8, port);

	return (3);
}

static unsigned int build_pop (unsigned int * array) {
	unsigned int size        = array [1],
	             to          = array [2],
	             destination = array [3];

	short_prefix (size);

	inset ((to == REG) && (upper (destination)), 0x41);

	inset (to == REG, 0x58 + 0x01 * (destination & 0x07));
	inset (to == MEM, 0x8f);
	inset (to == MEM, 0x05);

	inset_memory (to == MEM, D32, destination, 0);

	return (3);
}

static unsigned int build_push (unsigned int * array) {
	unsigned int size   = array [1],
	             from   = array [2],
	             source = array [3];

	short_prefix (size);

	inset ((from == REG) && (upper (source)), 0x41);

	inset (from == REG, 0x50 + 0x01 * (source & 0x07));
	inset (from == MEM, 0xff);
	inset (from == MEM, 0x35);
	inset (from == IMM, 0x68 + 0x02 * (size == D8));

	inset_memory (from == MEM, D32,  source, 0);
	inset_immediate (from == IMM, size, source);

	return (3);
}

static void assemble_clean_up (void) {
	if (!assemble_clean_up_queued) {
		return;
	}

	free (text_sector_byte);
	free (empty_array);
	free (empty_imbue);
	free (empty_store);
}

unsigned int    nopification     = 1;
unsigned int    text_entry_point = 0;
unsigned int    text_sector_size = 0;
unsigned char * text_sector_byte = NULL;

int was_instruction_array_empty = 0;

void assemble (unsigned int count, unsigned int * array) {
	unsigned int index;

	if ((count == 0) || (array == NULL)) {
		was_instruction_array_empty = 1;
		return;
	}

	text_sector_byte = calloc (4096UL, sizeof (* text_sector_byte));
	empty_array      = calloc (1024UL, sizeof (* empty_array));
	empty_imbue      = calloc (1024UL, sizeof (* empty_imbue));
	empty_store      = calloc (1024UL, sizeof (* empty_store));

	if (!assemble_clean_up_queued) {
		atexit (assemble_clean_up);
		assemble_clean_up_queued = ! assemble_clean_up_queued;
	}

	for (index = 0; index < count; ++index) {
		inset ((nopification) && (array [index] > ASMDIRREP), 0x90);

		if ((array [index] >= REGULAR_BEGIN) && (array [index] <= REGULAR_END)) {
			index += build_regular (& array [index]);
		} else if ((array [index] >= IRREGULAR_BEGIN) && (array [index] <= IRREGULAR_END)) {
			index += build_irregular (& array [index]);
		} else if ((array [index] >= SPECIAL_1_BEGIN) && (array [index] <= SPECIAL_1_END)) {
			index += build_special_1 (& array [index]);
		} else if ((array [index] >= SPECIAL_2_BEGIN) && (array [index] <= SPECIAL_2_END)) {
			index += build_special_2 (& array [index]);
		} else if ((array [index] >= JUMP_IF_BEGIN) && (array [index] <= JUMP_IF_END)) {
			index += build_jump_if (& array [index]);
		} else if ((array [index] >= MOVE_IF_BEGIN) && (array [index] <= MOVE_IF_END)) {
			index += build_move_if (& array [index]);
		} else if ((array [index] >= FLOAT_BEGIN) && (array [index] <= FLOAT_END)) {
			index += build_float (& array [index]);
		} else if ((array [index] == IN) || (array [index] == OUT)) {
			index += build_in_out (& array [index]);
		} else switch (array [index]) {
			case ASMDIRREL: index += store_relative  (& array [index]); break;
			case ASMDIRMEM: index += store_memory    (& array [index]); break;
			case ASMDIRIMM: index += store_immediate (& array [index]); break;
			case JMP:       index += build_jump      (& array [index]); break;
			case MOV:       index += build_move      (& array [index]); break;
			case CALL:      index += build_call      (& array [index]); break;
			case ENTER:     index += build_enter     (& array [index]); break;
			case POP:       index += build_pop       (& array [index]); break;
			case PUSH:      index += build_push      (& array [index]); break;
			// IS IT BAD TO JUST QUIT?
			default:        exit ((int) array [index]);
		}
	}

	text_entry_point = empty_store [0];

	for (index = 1; index < empty_holes; ++index) {
		unsigned int set = 0;
		unsigned int get = empty_array [index];

		replace ((unsigned char *) & set, & text_sector_byte [get], sizeof (set));

		set += empty_store [empty_imbue [index]];

		replace (& text_sector_byte [get], (unsigned char *) & set, sizeof (set));
	}
}