#include "boot-lib.h"

// lexer

int is_digit(int ch) {
    return '0' <= ch && ch <= '9';
}

int is_id_start(int ch) {
    return 'a' <= ch && ch <= 'z' || 'A' <= ch && ch <= 'Z' || ch == '_';
}

int is_id_cont(int ch) {
    return is_id_start(ch) || is_digit(ch);
}

int token_state;
int token_type;
int token_data;

const int TOKEN_EOF = 0;
const int TOKEN_SEMICOLON = 1;
const int TOKEN_ADD = 2;
const int TOKEN_MINUS = 3;
const int TOKEN_STAR = 4;
const int TOKEN_DIV = 5;
const int TOKEN_REM = 6;
const int TOKEN_ASSIGN = 7;
const int TOKEN_COMMA = 8;
const int TOKEN_DOT = 9;
const int TOKEN_LSHIFT = 10;
const int TOKEN_RSHIFT = 11;
const int TOKEN_AND = 12;
const int TOKEN_OR = 13;
const int TOKEN_XOR = 14;
const int TOKEN_COMPL = 15;
const int TOKEN_NOT = 16;
const int TOKEN_LAND = 17;
const int TOKEN_LOR = 18;
const int TOKEN_ELLIPSIS = 19;
const int TOKEN_INC = 20;
const int TOKEN_DEC = 21;

const int TOKEN_EQ = 40;
const int TOKEN_NE = 41;
const int TOKEN_LT = 42;
const int TOKEN_GT = 43;
const int TOKEN_LE = 44;
const int TOKEN_GE = 45;

const int TOKEN_PAREN_LEFT = 50;
const int TOKEN_PAREN_RIGHT = 51;
const int TOKEN_BRACKET_LEFT = 52;
const int TOKEN_BRACKET_RIGHT = 53;
const int TOKEN_BRACE_LEFT = 54;
const int TOKEN_BRACE_RIGHT = 55;

const int TOKEN_STRING = 99;
const int TOKEN_NUMBER = 100;
const int TOKEN_ID = 101;
const int TOKEN_IF = 102;
const int TOKEN_ELSE = 103;
const int TOKEN_WHILE = 104;
const int TOKEN_FOR = 105;
const int TOKEN_DO = 106;
const int TOKEN_BREAK = 107;
const int TOKEN_CONTINUE = 108;
const int TOKEN_RETURN = 109;

const int TOKEN_CONST = 127;
const int TOKEN_VOID = 128;
const int TOKEN_INT = 129;
const int TOKEN_CHAR = 130;

const int TYPE_VOID = 0;
const int TYPE_INT = 1;
const int TYPE_CHAR = 2;
const int TYPE_VOID_PTR = 16;
const int TYPE_INT_PTR = 17;
const int TYPE_CHAR_PTR = 18;

const int TYPE_PTR_MASK = 16;
const int TYPE_TOKEN_MASK = 128;

int parse_int(int ch) {
    int num = ch - '0';
    while (is_digit(ch = getchar())) {
        num = num * 10;
        num = num + ch - '0';
    }
    ungetchar(ch);
    return num;
}

int get_escaped_char() {
    int ch = getchar();
    if (ch == 'n') {
        ch = '\n';
    } else if (ch == 't') {
        ch = '\t';
    } else if (ch == 'r') {
        ch = '\r';
    } else if (ch == '0') {
        ch = '\0';
    } else if (ch == '\\') {
        ch = '\\';
    } else if (ch == '\'') {
        ch = '\'';
    } else if (ch == '\"') {
        ch = '\"';
    } else {
        eprintf("unexpected escaped character: %c\n", ch);
        exit(1);
    }
    return ch;
}

int streq(const char* s1, const char* s2) {
    while (*s1 && *s2 && *s1 == *s2) {
        s1++;
        s2++;
    }
    return *s1 == *s2;
}

char string_table[65536];
int string_offset;
int string_lut[4096];
int string_lut_size;
int parse_string() {
    int offset = string_offset;
    int ch;
    while ((ch = getchar()) != '"') {
        if (ch == -1 || ch == '\n') {
            eprintf("expecting '\"'\n");
            exit(1);
        }
        if (ch == '\\') {
            ch = get_escaped_char();
        }
        string_table[string_offset++] = ch;
    }
    string_table[string_offset++] = 0;
    string_lut[string_lut_size] = offset;
    return string_lut_size++;
}

char id_table[65536];
int id_offset;
int id_lut[4096];
int id_lut_size;
int parse_id(int ch) {
    int offset = id_offset;
    id_table[id_offset++] = ch;
    while (is_id_cont(ch = getchar())) {
        id_table[id_offset++] = ch;
    }
    ungetchar(ch);
    id_table[id_offset++] = 0;
    id_lut[id_lut_size] = offset;
    return id_lut_size++;
}

void rewind_id(int new_data) {
    id_offset = id_lut[token_data];
    token_data = new_data;
    --id_lut_size;
}

void dedup_id() {
    int last_id = id_lut_size - 1;
    char* latest = id_table + id_lut[last_id];
    for (int i = 0; i < last_id; i++) {
        char* candidate = id_table + id_lut[i];
        if (streq(candidate, latest)) {
            rewind_id(i);
            return;
        }
    }
}

void parse_id_like(int ch) {
    token_type = TOKEN_ID;
    token_data = parse_id(ch);
    char* id = id_table + id_lut[token_data];
    if (streq(id, "int")) {
        token_type = TOKEN_INT;
    } else if (streq(id, "if")) {
        token_type = TOKEN_IF;
    } else if (streq(id, "else")) {
        token_type = TOKEN_ELSE;
    } else if (streq(id, "while")) {
        token_type = TOKEN_WHILE;
    } else if (streq(id, "break")) {
        token_type = TOKEN_BREAK;
    } else if (streq(id, "continue")) {
        token_type = TOKEN_CONTINUE;
    } else if (streq(id, "return")) {
        token_type = TOKEN_RETURN;
    } else if (streq(id, "void")) {
        token_type = TOKEN_VOID;
    } else if (streq(id, "const")) {
        token_type = TOKEN_CONST;
    } else if (streq(id, "char")) {
        token_type = TOKEN_CHAR;
    } else if (streq(id, "for")) {
        token_type = TOKEN_FOR;
    } else if (streq(id, "do")) {
        token_type = TOKEN_DO;
    }
    if (token_type != TOKEN_ID) {
        rewind_id(0);
    } else {
        dedup_id();
    }
}

void unget_token() {
    token_state = 1;
}

void next_token() {
    if (token_state) {
        token_state = 0;
        return;
    }
    int ch = getchar();
    while (ch == ' ' || ch == '\t' || ch == '\r' || ch == '\n') {
        ch = getchar();
    }
    if (ch == -1) {
        token_type = TOKEN_EOF;
    } else if (ch == '(') {
        token_type = TOKEN_PAREN_LEFT;
    } else if (ch == ')') {
        token_type = TOKEN_PAREN_RIGHT;
    } else if (ch == '[') {
        token_type = TOKEN_BRACKET_LEFT;
    } else if (ch == ']') {
        token_type = TOKEN_BRACKET_RIGHT;
    } else if (ch == '{') {
        token_type = TOKEN_BRACE_LEFT;
    } else if (ch == '}') {
        token_type = TOKEN_BRACE_RIGHT;
    } else if (ch == '+') {
        int ch2 = getchar();
        if (ch2 == '+') {
            token_type = TOKEN_INC;
        } else {
            ungetchar(ch2);
            token_type = TOKEN_ADD;
        }
    } else if (ch == '-') {
        int ch2 = getchar();
        if (ch2 == '-') {
            token_type = TOKEN_DEC;
        } else {
            ungetchar(ch2);
            token_type = TOKEN_MINUS;
        }
    } else if (ch == '*') {
        token_type = TOKEN_STAR;
    } else if (ch == '/') {
        int ch2 = getchar();
        if (ch2 == '/') {
            do ch = getchar(); while (ch != -1 && ch != '\n');
            next_token();
            return;
        } else if (ch2 == '*') {
            while (1) {
                ch = getchar();
                if (ch == -1) {
                    eprintf("expecting '*/'\n");
                    exit(1);
                }
                if (ch == '*') {
                    ch = getchar();
                    if (ch == '/') {
                        break;
                    }
                }
            }
            next_token();
            return;
        } else {
            ungetchar(ch2);
            token_type = TOKEN_DIV;
        }
    } else if (ch == '%') {
        token_type = TOKEN_REM;
    } else if (ch == ';') {
        token_type = TOKEN_SEMICOLON;
    } else if (ch == ',') {
        token_type = TOKEN_COMMA;
    } else if (ch == '<') {
        int ch2 = getchar();
        if (ch2 == '=') {
            token_type = TOKEN_LE;
        } else if (ch2 == '<') {
            token_type = TOKEN_LSHIFT;
        } else {
            ungetchar(ch2);
            token_type = TOKEN_LT;
        }
    } else if (ch == '>') {
        int ch2 = getchar();
        if (ch2 == '=') {
            token_type = TOKEN_GE;
        } else if (ch2 == '>') {
            token_type = TOKEN_RSHIFT;
        } else {
            ungetchar(ch2);
            token_type = TOKEN_GT;
        }
    } else if (ch == '=') {
        int ch2 = getchar();
        if (ch2 == '=') {
            token_type = TOKEN_EQ;
        } else {
            ungetchar(ch2);
            token_type = TOKEN_ASSIGN;
        }
    } else if (ch == '!') {
        int ch2 = getchar();
        if (ch2 == '=') {
            token_type = TOKEN_NE;
        } else {
            ungetchar(ch2);
            token_type = TOKEN_NOT;
        }
    } else if (ch == '&') {
        int ch2 = getchar();
        if (ch2 == '&') {
            token_type = TOKEN_LAND;
        } else {
            ungetchar(ch2);
            token_type = TOKEN_AND;
        }
    } else if (ch == '|') {
        int ch2 = getchar();
        if (ch2 == '|') {
            token_type = TOKEN_LOR;
        } else {
            ungetchar(ch2);
            token_type = TOKEN_OR;
        }
    } else if (ch == '^') {
        token_type = TOKEN_XOR;
    } else if (ch == '~') {
        token_type = TOKEN_COMPL;
    } else if (ch == '\'') {
        token_type = TOKEN_NUMBER;
        token_data = getchar();
        if (token_data == '\\') {
            token_data = get_escaped_char();
        }
        if (getchar() != '\'') {
            eprintf("expecting '\n");
            exit(1);
        }
    } else if (ch == '"') {
        token_type = TOKEN_STRING;
        token_data = parse_string();
    } else if (ch == '.') {
        int ch2 = getchar();
        if (ch2 == '.') {
            int ch3 = getchar();
            if (ch3 == '.') {
                token_type = TOKEN_ELLIPSIS;
            } else {
                eprintf("unexpected character: %c\n", ch3);
                exit(1);
            }
        } else {
            eprintf("unexpected character: %c\n", ch2);
            exit(1);
        }
    } else if (is_digit(ch)) {
        token_type = TOKEN_NUMBER;
        token_data = parse_int(ch);
    } else if (is_id_start(ch)) {
        parse_id_like(ch);
    } else {
        eprintf("unexpected character: %c(%d)\n", ch, ch);
        exit(1);
    }
    eprintf("token: %d\n", token_type);
    if (token_type == TOKEN_ID) {
        const char* name = id_table + id_lut[token_data];
        eprintf("  id: %s\n", name);
    } else if (token_type == TOKEN_NUMBER) {
        eprintf("  number: %d\n", token_data);
    }
}

void expect_token(int expected_type) {
    next_token();
    if (token_type != expected_type) {
        eprintf("unexpected token: %d, should be %d\n", token_type, expected_type);
        exit(1);
    }
}

void ignore_const() {
    if (token_type == TOKEN_CONST) {
        next_token();
    }
}

int parse_type() {
    ignore_const();
    if (token_type == TOKEN_INT || token_type == TOKEN_CHAR || token_type == TOKEN_VOID) {
        int type = token_type & ~TYPE_TOKEN_MASK;
        next_token();
        ignore_const();
        if (token_type == TOKEN_STAR) {
            ignore_const();
            return type | TYPE_PTR_MASK;
        }
        unget_token();
        return type;
    } else {
        return -1;
    }
}

// asm

int epilog_label;

int local_table[4096]; // id -> local id
int next_local_id = 12;
int max_local_id = 12;

const int MARKER_TEMP = 0;
const int MARKER_SCALAR = 1;
const int MARKER_ARRAY = 2;
const int MARKER_FUNCTION = 3;

int local_marker[4096];
int global_marker[4096];
int local_type[4096];
int global_type[4096];

int reg_type[4096];
int next_reg_id = 18;
int max_reg_id = 18;
int indirection[4096];
int overflow[4096];

const int REG_ZERO = 0;
const int REG_RA = 1;
const int REG_SP = 2;
const int REG_GP = 3;
const int REG_TP = 4;
const int REG_T0 = 5;
const int REG_T1 = 6;
const int REG_T2 = 7;
const int REG_FP = 8;
const int REG_S1 = 9;
const int REG_A0 = 10;
const int REG_A1 = 11;
const int REG_A2 = 12;
const int REG_A3 = 13;
const int REG_A4 = 14;
const int REG_A5 = 15;
const int REG_A6 = 16;
const int REG_A7 = 17;
const int REG_S2 = 18;
const int REG_S3 = 19;
const int REG_S4 = 20;
const int REG_S5 = 21;
const int REG_S6 = 22;
const int REG_S7 = 23;
const int REG_S8 = 24;
const int REG_S9 = 25;
const int REG_S10 = 26;
const int REG_S11 = 27;
const int REG_T3 = 28;
const int REG_T4 = 29;
const int REG_T5 = 30;
const int REG_T6 = 31;

void reset_reg() {
    next_reg_id = REG_S2;
    for (int i = 0; i < 4096; ++i) {
        reg_type[i] = TYPE_VOID;
        indirection[i] = 0;
        overflow[i] = 0;
    }
}

const char* reg_name(int reg) {
    if (reg == 0) return "zero";
    if (reg == 1) return "ra";
    if (reg == 2) return "sp";
    if (reg == 3) return "gp";
    if (reg == 4) return "tp";
    if (reg == 5) return "t0";
    if (reg == 6) return "t1";
    if (reg == 7) return "t2";
    if (reg == 8) return "fp";
    // reserved begin
    if (reg == 9) return "s1";
    if (reg == 10) return "a0";
    if (reg == 11) return "a1";
    if (reg == 12) return "a2";
    if (reg == 13) return "a3";
    if (reg == 14) return "a4";
    if (reg == 15) return "a5";
    if (reg == 16) return "a6";
    if (reg == 17) return "a7";
    // allocation begin
    if (reg == 18) return "s2";
    if (reg == 19) return "s3";
    if (reg == 20) return "s4";
    if (reg == 21) return "s5";
    if (reg == 22) return "s6";
    if (reg == 23) return "s7";
    if (reg == 24) return "s8";
    if (reg == 25) return "s9";
    if (reg == 26) return "s10";
    if (reg == 27) return "s11";
    // overflow begin
    if (reg == 28) return "t3";
    if (reg == 29) return "t4";
    if (reg == 30) return "t5";
    if (reg == 31) return "t6";
    return 0;
}

int is_overflow(int reg) {
    return reg > REG_S11;
}

void reset_local() {
    next_local_id = 12;
    max_local_id = 12;
    for (int i = 0; i < 4096; ++i) {
        local_table[i] = 0;
        local_marker[i] = MARKER_TEMP;
        local_type[i] = TYPE_VOID;
    }
    reset_reg();
}

void reset_temp() {
    while (next_local_id > 12 && local_marker[next_local_id - 1] == MARKER_TEMP) {
        --next_local_id;
    }
    reset_reg();
}

int next_local_slot(int type) {
    int slot = next_local_id++;
    local_type[slot] = type;
    if (next_local_id > max_local_id) {
        max_local_id = next_local_id;
    }
    return slot;
}

int declare_local(int id, int type) {
    if (local_table[id] != 0) return local_table[id];
    int slot = next_local_slot(type);
    local_marker[slot] = MARKER_SCALAR;
    return local_table[id] = slot;
}

int declare_local_array(int id, int type, int size) {
    if (local_table[id] != 0) return local_table[id];
    int slot;
    for (int i = 0; i < size; ++i) local_marker[slot = next_local_slot(type)] = MARKER_ARRAY;
    return local_table[id] = slot;
}

void declare_global(int id, int marker, int type) {
    global_marker[id] = marker;
    global_type[id] = type;
}

int next_reg(int type) {
    int reg = next_reg_id++;
    if (is_overflow(reg)) {
        int slot = next_local_slot(type);
        local_marker[slot] = MARKER_TEMP;
        overflow[reg] = slot;
    }
    reg_type[reg] = type;
    if (next_reg_id > max_reg_id) {
        max_reg_id = next_reg_id;
    }
    return reg;
}


// prolog & epilog helpers

int check_itype_immediate(int value) {
    return value >= -2048 && value <= 2047;
}

void asm_ld(const char* rd, int imm, const char* rs) {
    if (check_itype_immediate(imm)) {
        printf("  ld %s, %d(%s)\n", rd, imm, rs);
    } else {
        printf("  li t0, %d\n", imm);
        printf("  add t0, %s, t0\n", rs);
        printf("  ld %s, 0(t0)\n", rd);
    }
}

void asm_sd(const char* rs1, int imm, const char* rs2) {
    if (check_itype_immediate(imm)) {
        printf("  sd %s, %d(%s)\n", rs1, imm, rs2);
    } else {
        printf("  li t0, %d\n", imm);
        printf("  add t0, %s, t0\n", rs2);
        printf("  sd %s, 0(t0)\n", rs1);
    }
}

void asm_addi(const char* rd, const char* rs, int imm) {
    if (check_itype_immediate(imm)) {
        printf("  addi %s, %s, %d\n", rd, rs, imm);
    } else {
        printf("  li t0, %d\n", imm);
        printf("  add %s, %s, t0\n", rd, rs);
    }
}

// assembly helpers

// address loaders
// rd must be one of 0, 1, 2
void load_local_address(int rd, int slot_id) {
    // TODO use sp instead
    int offset = -slot_id * 8 - 8;
    const char* rd_name = reg_name(rd);
    if (check_itype_immediate(offset)) {
        printf("  addi %s, fp, %d\n", rd_name, offset);
    } else {
        printf("  li %s, %d\n", rd_name, offset);
        printf("  add %s, fp, %s\n", rd_name, rd_name);
    }   
}

const char* load_op(int reg) {
    int type = reg_type[reg];
    if (type & TYPE_PTR_MASK) {
        return "ld";
    } else if (type == TYPE_CHAR) {
        return "lb";
    } else  { // int
        return "lw";
    }
}

const char* store_op_of_type(int type) {
    if (type & TYPE_PTR_MASK) {
        return "sd";
    } else if (type == TYPE_CHAR) {
        return "sb";
    } else  { // int
        return "sw";
    }
}

const char* store_op(int reg) {
    return store_op_of_type(reg_type[reg]);
}

// load a non-trivial register into t0, t1 or t2
// rd must be one of t0, t1, t2
void load(int rd, int reg) {
    const char* op = load_op(reg);
    const char* rd_name = reg_name(rd);
    if (is_overflow(reg)) {
        load_local_address(rd, overflow[reg]);
        if (indirection[reg]) {
            printf("  ld %s, 0(%s)\n", rd_name, rd_name);
        }
        reg = rd;
    }
    printf("  %s %s, 0(%s) # load non-trivial register\n", op, rd_name, reg_name(reg));
}

// store t0 into a non-trivial register
void store_t0(int reg) {
    const char* op = store_op(reg);
    if (is_overflow(reg)) {
        load_local_address(REG_T2, overflow[reg]);
        if (indirection[reg]) {
            printf("  ld t2, 0(t2)\n");
        }
        reg = REG_T2;
    }
    printf("  %s t0, 0(%s) # store non-trivial register\n", op, reg_name(reg));
}

int is_nontrivial(int reg) {
    return is_overflow(reg) || indirection[reg];
}

void _asm_r(const char* op, int rd, int rs1) {
    const char* rd_name = reg_name(rd);
    const char* rs1_name = reg_name(rs1);
    if (is_nontrivial(rd)) rd_name = "t0";
    if (is_nontrivial(rs1)) {
        rs1_name = "t0";
        load(REG_T0, rs1);
    }
    printf("  %s %s, %s\n", op, rd_name, rs1_name);
    if (is_nontrivial(rd)) {
        store_t0(rd);
    }
}

void _asm_rr(const char* op, int rd, int rs1, int rs2) {
    const char* rd_name = reg_name(rd);
    const char* rs1_name = reg_name(rs1);
    const char* rs2_name = reg_name(rs2);
    if (is_nontrivial(rd)) rd_name = "t0";
    if (is_nontrivial(rs1)) {
        rs1_name = "t0";
        load(REG_T0, rs1);
    }
    if (is_nontrivial(rs2)) {
        rs2_name = "t1";
        load(REG_T1, rs2);
    }
    printf("  %s %s, %s, %s\n", op, rd_name, rs1_name, rs2_name);
    if (is_nontrivial(rd)) {
        store_t0(rd);
    }
}

void _asm_ri(const char* op, int rd, int rs1, int imm) {
    const char* rd_name = reg_name(rd);
    const char* rs1_name = reg_name(rs1);
    if (is_nontrivial(rd)) rd_name = "t0";
    if (is_nontrivial(rs1)) {
        rs1_name = "t0";
        load(REG_T0, rs1);
    }
    printf("  %s %s, %s, %d\n", op, rd_name, rs1_name, imm);
    if (is_nontrivial(rd)) {
        store_t0(rd);
    }
}

void _asm_branch(const char* op, int rs1, int label) {
    const char* rs1_name = reg_name(rs1);
    if (is_nontrivial(rs1)) {
        rs1_name = "t0";
        load(REG_T0, rs1);
    }
    printf("  %s %s, L%d\n", op, rs1_name, label);
}

int asm_r(int type, const char* op, int rs1) {
    int rd = next_reg(type);
    _asm_r(op, rd, rs1);
    return rd;
}

int asm_rr(int type, const char* op, int rs1, int rs2) {
    int rd = next_reg(type);
    _asm_rr(op, rd, rs1, rs2);
    return rd;
}

void asm_mv(int rd, int rs1) {
    _asm_r("mv", rd, rs1);
}

int materialize_t0(int type) {
    int rd = next_reg(type);
    asm_mv(rd, REG_T0);
    return rd;
}

int materialize_address(int type, int marker) {
    if (marker == MARKER_ARRAY) {
        type = type | TYPE_PTR_MASK;
    }
    int rd = materialize_t0(TYPE_VOID_PTR);
    reg_type[rd] = type;
    indirection[rd] = marker == MARKER_SCALAR;
    return rd;
}

int lookup_from_slot(int slot) {
    load_local_address(REG_T0, slot);
    return materialize_address(local_type[slot], local_marker[slot]);
}

int lookup(int id) {
    int slot = local_table[id];
    if (slot) {
        return lookup_from_slot(slot);
    }
    const char* name = id_table + id_lut[id];
    if (global_marker[id]) {
        if (global_marker[id] == MARKER_FUNCTION) {
            eprintf("function name must not appear outside function call: %s\n", name);
            exit(1);
        }
        printf("  la t0, %s # id: %d\n", name, id);
        return materialize_address(global_type[id], global_marker[id]);
    }
    eprintf("unresolved identifier: %s\n", name);
    exit(1);
}


int next_label_id = 0;
int next_label() {
    return next_label_id++;
}

int asm_label(int label) {
    printf("L%d:\n", label);
    return label;
}

int asm_r_arith(const char* op, int rs1) {
    if (reg_type[rs1] & TYPE_PTR_MASK) {
        eprintf("pointer cannot be arithmetically operated by %s\n", op);
        exit(1);
    }
    return asm_r(TYPE_INT, op, rs1);
}

int asm_rr_arith(const char* op, int rs1, int rs2) {
    if (reg_type[rs1] & TYPE_PTR_MASK || reg_type[rs2] & TYPE_PTR_MASK) {
        eprintf("pointer cannot be arithmetically operated by %s\n", op);
        exit(1);
    }
    return asm_rr(TYPE_INT, op, rs1, rs2);
}

int asm_rr_cmp(const char* op, int rs1, int rs2) {
    // since NULL is virtually 0, it is considered a valid example of a pointer comparing with an integer
    return asm_rr(TYPE_INT, op, rs1, rs2);
}

void asm_beqz(int rs1, int label) {
    _asm_branch("beqz", rs1, label);
}

void asm_bnez(int rs1, int label) {
    _asm_branch("bnez", rs1, label);
}

void asm_j(int label) {
    printf("  j L%d\n", label);
}

int break_label_stack[4096];
int cont_label_stack[4096];
int break_label_stack_size;
int cont_label_stack_size;

int asm_get_break_label() {
    return break_label_stack[break_label_stack_size - 1];
}

int asm_get_cont_label() {
    return cont_label_stack[cont_label_stack_size - 1];
}

void asm_push_label(int break_label, int cont_label) {
    break_label_stack[break_label_stack_size++] = break_label;
    cont_label_stack[cont_label_stack_size++] = cont_label;
}

void asm_pop_label() {
    --break_label_stack_size;
    --cont_label_stack_size;
}

int step_of(int type) {
    if (type == TYPE_INT_PTR) {
        return 4;
    }
    return 1;
}

int asm_add(int lhs, int rhs) {
    int type1 = reg_type[lhs] & TYPE_PTR_MASK;
    int type2 = reg_type[rhs] & TYPE_PTR_MASK;
    if (type1 != type2) {
        int ptr;
        int idx;
        if (type1) {
            ptr = lhs;
            idx = rhs;
        } else {
            ptr = rhs;
            idx = lhs;
        }
        int ptr_type = reg_type[ptr];
        if (ptr_type == TYPE_VOID_PTR) {
            eprintf("void pointer cannot be arithmetically operated\n");
            exit(1);
        }
        int offset = next_reg(TYPE_INT);
        int shift = 2 * (ptr_type == TYPE_INT_PTR);
        _asm_ri("slli", offset, idx, shift);
        return asm_rr(ptr_type, "add", ptr, offset);
    }
    if (type1 && type2) {
        eprintf("operands of addition cannot be both pointers\n");
        exit(1);
    }
    return asm_rr(TYPE_INT, "add", lhs, rhs);
}

int asm_sub(int lhs, int rhs) {
    int lhs_type = reg_type[lhs];
    int rhs_type = reg_type[rhs];
    int type1 = lhs_type & TYPE_PTR_MASK;
    int type2 = rhs_type & TYPE_PTR_MASK;
    if (type1 && type2) {
        if (lhs_type != rhs_type) {
            eprintf("pointer type mismatch\n");
            exit(1);
        }
        if (lhs_type == TYPE_VOID_PTR) {
            eprintf("void pointer cannot be arithmetically operated\n");
            exit(1);
        }
        int difference = asm_rr(TYPE_INT, "sub", lhs, rhs);
        int shift = 2 * (lhs_type == TYPE_INT_PTR);
        _asm_ri("slli", REG_T0, difference, shift);
        return materialize_t0(TYPE_INT);
    }
    if (type1) {
        int neg = asm_r_arith("neg", rhs);
        return asm_add(lhs, neg);
    }
    return asm_rr_arith("sub", lhs, rhs);
}

int dereference(int reg) {
    if (indirection[reg]) {
        load(reg, reg);
    } else {
        indirection[reg] = 1;
    }
    reg_type[reg] = reg_type[reg] & ~TYPE_PTR_MASK;
    return reg;
}

int addressof(int reg) {
    if (indirection[reg] && !(reg_type[reg] & TYPE_PTR_MASK)) {
        reg_type[reg] = reg_type[reg] | TYPE_PTR_MASK;
        indirection[reg] = 0;
    } else {
        printf("cannot take address of this expression");
    }
    return reg;
}

// parser
int parse_expr();

int parse_function_call(int id) {
    const char* name = id_table + id_lut[id];
    if (global_marker[id] != MARKER_FUNCTION) {
        eprintf("not a function name: %s\n", name);
        exit(1);
    }
    int arg = 0;
    int args[8];
    while (1) {
        next_token();
        if (token_type == TOKEN_PAREN_RIGHT) {
            break;
        }
        unget_token();
        if (arg >= 8) {
            eprintf("too many arguments\n");
            exit(1);
        }
        args[arg++] = parse_expr();
        next_token();
        if (token_type == TOKEN_COMMA) {
            // continue;
        } else if (token_type == TOKEN_PAREN_RIGHT) {
            break;
        } else {
            eprintf("expecting ',' or ')'\n");
            exit(1);
        }
    }
    for (int i = 0; i < arg; ++i) {
        asm_mv(i + REG_A0, args[i]);
    }
    // TODO saved by caller
    printf("  call %s\n", name);
    // TODO saved by caller
    int type = global_type[id];
    if (type != TYPE_VOID) {
        printf("  mv t0, a0\n");
        return materialize_t0(type);
    }
    return -1;
}

int parse_primary_expr() {
    next_token();
    if (token_type == TOKEN_EOF) {
        exit(1);
    } else if (token_type == TOKEN_NUMBER) {
        printf("  li t0, %d\n", token_data);
        return materialize_t0(TYPE_INT);
    } else if (token_type == TOKEN_ID) {
        next_token();
        if (token_type == TOKEN_PAREN_LEFT) {
            return parse_function_call(token_data);
        }
        unget_token();
        return lookup(token_data);
    } else if (token_type == TOKEN_STRING) {
        printf("  la t0, .LC%d\n", token_data);
        return materialize_t0(TYPE_CHAR_PTR);
    } else if (token_type == TOKEN_PAREN_LEFT) {
        int reg = parse_expr();
        expect_token(TOKEN_PAREN_RIGHT);
        return reg;
    } else {
        eprintf("unexpected token in primary expression: %d\n", token_type);
        exit(1);
    }
}

int parse_postfix_expr() {
    int lhs = parse_primary_expr();
    while (1) {
        next_token();
        if (token_type == TOKEN_INC) {
            int type = reg_type[lhs];
            int reg = next_reg(type);
            asm_mv(reg, lhs);
            _asm_ri("addi", lhs, lhs, step_of(type));
            lhs = reg;
        } else if (token_type == TOKEN_DEC) {
            int type = reg_type[lhs];
            int reg = next_reg(type);
            asm_mv(reg, lhs);
            _asm_ri("addi", lhs, lhs, -step_of(type));
            lhs = reg;
        } else if (token_type == TOKEN_BRACKET_LEFT) {
            int rhs = parse_expr();
            expect_token(TOKEN_BRACKET_RIGHT);
            lhs = dereference(asm_add(lhs, rhs));
        } else {
            unget_token();
            break;
        }
    }
    return lhs;
}

int parse_prefix_expr() {
    next_token();
    if (token_type == TOKEN_AND) {
        int reg = parse_postfix_expr();
        int type = reg_type[reg];
        if (type & TYPE_PTR_MASK) {
            eprintf("cannot take address of a pointer\n");
            exit(1);
        }
        return addressof(reg);
    } else if (token_type == TOKEN_STAR) {
        int reg = parse_postfix_expr();
        int type = reg_type[reg];
        if (!(type & TYPE_PTR_MASK)) {
            eprintf("cannot dereference a non-pointer\n");
            exit(1);
        }
        if (type == TYPE_VOID_PTR) {
            eprintf("cannot dereference void pointer\n");
            exit(1);
        }
        return dereference(reg);
    } else if (token_type == TOKEN_MINUS) {
        int reg = parse_postfix_expr();
        return asm_r_arith("neg", reg);
    } else if (token_type == TOKEN_COMPL) {
        int reg = parse_postfix_expr();
        return asm_r_arith("not", reg);
    } else if (token_type == TOKEN_NOT) {
        int reg = parse_postfix_expr();
        return asm_r(TYPE_INT, "seqz", reg);
    } else if (token_type == TOKEN_INC) {
        int reg = parse_postfix_expr();
        _asm_ri("addi", reg, reg, step_of(reg_type[reg]));
        return reg;
    } else if (token_type == TOKEN_DEC) {
        int reg = parse_postfix_expr();
        _asm_ri("addi", reg, reg, -step_of(reg_type[reg]));
        return reg;
    } else {
        unget_token();
        return parse_postfix_expr();
    }
}

int parse_mul_expr() {
    int lhs = parse_prefix_expr();
    while (1) {
        next_token();
        if (token_type == TOKEN_STAR) {
            int rhs = parse_prefix_expr();
            lhs = asm_rr_arith("mul", lhs, rhs);
        } else if (token_type == TOKEN_DIV) {
            int rhs =  parse_prefix_expr();
            lhs = asm_rr_arith("div", lhs, rhs);
        } else if (token_type == TOKEN_REM) {
            int rhs =  parse_prefix_expr();
            lhs = asm_rr_arith("rem", lhs, rhs);
        } else {
            unget_token();
            break;
        }
    }
    return lhs;
}

int parse_add_expr() {
    int lhs = parse_mul_expr();
    while (1) {
        next_token();
        if (token_type == TOKEN_ADD) {
            int rhs = parse_mul_expr();
            lhs = asm_add(lhs, rhs);
        } else if (token_type == TOKEN_MINUS) {
            int rhs = parse_mul_expr();
            lhs = asm_sub(lhs, rhs);
        } else {
            unget_token();
            break;
        }
    }
    return lhs;
}

int parse_shift_expr() {
    int lhs = parse_add_expr();
    while (1) {
        next_token();
        if (token_type == TOKEN_LSHIFT) {
            int rhs = parse_add_expr();
            lhs = asm_rr_arith("sll", lhs, rhs);
        } else if (token_type == TOKEN_RSHIFT) {
            int rhs = parse_add_expr();
            lhs = asm_rr_arith("sra", lhs, rhs);
        } else {
            unget_token();
            break;
        }
    }
    return lhs;
}

int parse_cmp_expr() {
    int lhs = parse_shift_expr();
    while (1) {
        next_token();
        if (token_type == TOKEN_LT) {
            int rhs = parse_shift_expr();
            lhs = asm_rr_cmp("slt", lhs, rhs);
        } else if (token_type == TOKEN_GT) {
            int rhs = parse_shift_expr();
            lhs = asm_rr_cmp("sgt", lhs, rhs);
        } else if (token_type == TOKEN_LE) {
            int rhs = parse_shift_expr();
            int sgt = asm_rr_cmp("sgt", lhs, rhs);
            lhs = asm_r(TYPE_INT, "seqz", sgt);
        } else if (token_type == TOKEN_GE) {
            int rhs = parse_shift_expr();
            int slt = asm_rr_cmp("slt", lhs, rhs);
            lhs = asm_r(TYPE_INT, "seqz", slt);
        } else {
            unget_token();
            break;
        }
    }
    return lhs;
}

int parse_eq_expr() {
    int lhs = parse_cmp_expr();
    while (1) {
        next_token();
        if (token_type == TOKEN_EQ) {
            int rhs = parse_cmp_expr();
            int xor0 = asm_rr_cmp("xor", lhs, rhs);
            lhs = asm_r(TYPE_INT, "seqz", xor0);
        } else if (token_type == TOKEN_NE) {
            int rhs = parse_cmp_expr();
            int xor0 = asm_rr_cmp("xor", lhs, rhs);
            lhs = asm_r(TYPE_INT, "snez", xor0);
        } else {
            unget_token();
            break;
        }
    }
    return lhs;
}

int parse_bitwise_and_expr() {
    int lhs = parse_eq_expr();
    while (1) {
        next_token();
        if (token_type == TOKEN_AND) {
            int rhs = parse_eq_expr();
            lhs = asm_rr_arith("and", lhs, rhs);
        } else {
            unget_token();
            break;
        }
    }
    return lhs;
}


int parse_bitwise_xor_expr() {
    int lhs = parse_bitwise_and_expr();
    while (1) {
        next_token();
        if (token_type == TOKEN_XOR) {
            int rhs = parse_bitwise_and_expr();
            lhs = asm_rr_arith("xor", lhs, rhs);
        } else {
            unget_token();
            break;
        }
    }
    return lhs;
}

int parse_bitwise_or_expr() {
    int lhs = parse_bitwise_xor_expr();
    while (1) {
        next_token();
        if (token_type == TOKEN_OR) {
            int rhs = parse_bitwise_xor_expr();
            lhs = asm_rr_arith("or", lhs, rhs);
        } else {
            unget_token();
            break;
        }
    }
    return lhs;
}

int parse_logical_and_expr() {
    int lhs = parse_bitwise_or_expr();
    int logical = 0;
    int label;
    int result;
    while (1) {
        next_token();
        if (token_type == TOKEN_LAND) {
            if (!logical) {
                logical = 1;
                label = next_label();
                result = next_reg(TYPE_INT);
                _asm_r("snez", result, lhs);
            }
            asm_beqz(result, label);
            int rhs = parse_bitwise_or_expr();
            _asm_r("snez", result, rhs);
        } else {
            unget_token();
            break;
        }
    }
    if (logical) {
        asm_label(label);
        return result;
    }
    return lhs;
}

int parse_logical_or_expr() {
    int lhs = parse_logical_and_expr();
    int logical = 0;
    int label;
    int result;
    while (1) {
        next_token();
        if (token_type == TOKEN_LOR) {
            if (!logical) {
                logical = 1;
                label = next_label();
                result = next_reg(TYPE_INT);
                _asm_r("snez", result, lhs);
            }
            asm_bnez(result, label);
            int rhs = parse_logical_and_expr();
            _asm_r("snez", result, rhs);
        } else {
            unget_token();
            break;
        }
    }
    if (logical) {
        asm_label(label);
        return result;
    }
    return lhs;
}

int parse_assign_expr() {
    int lhs = parse_logical_or_expr();
    next_token();
    if (token_type == TOKEN_ASSIGN) {
        int rhs = parse_assign_expr();
        asm_mv(lhs, rhs);
        return lhs;
    } else {
        unget_token();
        return lhs;
    }
}

int parse_expr() {
    return parse_assign_expr();
}

void parse_local_variable(int type) {
    if (type == TYPE_VOID) {
        eprintf("local variable of void type is not supported\n");
        exit(1);
    }
    expect_token(TOKEN_ID);
    int id = token_data;
    next_token();
    if (token_type == TOKEN_BRACKET_LEFT) {
        if (type & TYPE_PTR_MASK) {
            eprintf("local variable of array of pointers is not supported\n");
            exit(1);
        }
        expect_token(TOKEN_NUMBER);
        int size = token_data;
        expect_token(TOKEN_BRACKET_RIGHT);
        declare_local_array(id, type, size);
        return;
    } 
    int slot = declare_local(id, type);
    if (token_type == TOKEN_SEMICOLON) {
        unget_token();
        return;
    }
    unget_token();
    expect_token(TOKEN_ASSIGN);
    int reg = parse_expr();
    if (type != reg_type[reg]) {
        eprintf("type mismatch in assignment\n");
        exit(1);
    }
    asm_mv(REG_T0, reg);
    load_local_address(REG_T2, slot);
    printf("  %s t0, 0(t2)\n", store_op_of_type(type));
}

void parse_stmt();

void parse_if() {
    expect_token(TOKEN_PAREN_LEFT);
    int cond = parse_expr();
    int label1 = next_label();
    int label2 = next_label();
    asm_beqz(cond, label1);
    reset_temp();
    expect_token(TOKEN_PAREN_RIGHT);
    parse_stmt();
    asm_j(label2);
    asm_label(label1);
    next_token();
    if (token_type == TOKEN_ELSE) {
        parse_stmt();
    } else {
        unget_token();
    }
    asm_label(label2);
}

void parse_while() {
    expect_token(TOKEN_PAREN_LEFT);
    int break_label = next_label();
    int cont_label = next_label();
    asm_push_label(break_label, cont_label);
    asm_label(cont_label);
    int cond = parse_expr();
    asm_beqz(cond, break_label);
    reset_temp();
    expect_token(TOKEN_PAREN_RIGHT);
    parse_stmt();
    asm_j(cont_label);
    asm_label(break_label);
    asm_pop_label();
}

void parse_for() {
    expect_token(TOKEN_PAREN_LEFT);
    int cont_label = next_label();
    int break_label = next_label();
    int cond_label = next_label();
    int body_label = next_label();
    asm_push_label(break_label, cont_label);
    parse_stmt(); // init
    asm_label(cond_label);
    int cond = parse_expr();
    asm_beqz(cond, break_label);
    asm_j(body_label);
    reset_temp();
    expect_token(TOKEN_SEMICOLON);
    asm_label(cont_label);
    parse_expr(); // update
    reset_temp();
    expect_token(TOKEN_PAREN_RIGHT);
    asm_j(cond_label);
    asm_label(body_label);
    parse_stmt(); // body
    asm_j(cont_label);
    asm_label(break_label);
    asm_pop_label();
}

void parse_do_while() {
    int cont_label = next_label();
    int break_label = next_label();
    asm_push_label(break_label, cont_label);
    asm_label(cont_label);
    parse_stmt(); // body
    expect_token(TOKEN_WHILE);
    expect_token(TOKEN_PAREN_LEFT);
    int cond = parse_expr();
    asm_bnez(cond, cont_label);
    expect_token(TOKEN_PAREN_RIGHT);
    asm_label(break_label);
    asm_pop_label();
}

void parse_stmt() {
    next_token();
    int decl_type;
    if (token_type == TOKEN_IF) {
        parse_if();
        return;
    } else if (token_type == TOKEN_WHILE) {
        parse_while();
        return;
    } else if (token_type == TOKEN_FOR) {
        parse_for();
        return;
    } else if (token_type == TOKEN_DO) {
        parse_do_while();
    } else if (token_type == TOKEN_BRACE_LEFT) {
        while (1) {
            next_token();
            if (token_type == TOKEN_BRACE_RIGHT) {
                break;
            }
            unget_token();
            parse_stmt();
        }
        return;
    } else if (token_type == TOKEN_RETURN) {
        next_token();
        if (token_type == TOKEN_SEMICOLON) {
            asm_j(epilog_label);
            return;
        }
        unget_token();
        int rs1 = parse_expr();
        asm_mv(REG_A0, rs1);
        asm_j(epilog_label);
    } else if (token_type == TOKEN_BREAK) {
        int label = asm_get_break_label();
        asm_j(label);
    } else if (token_type == TOKEN_CONTINUE) {
        int label = asm_get_cont_label();
        asm_j(label);
    } else if (token_type == TOKEN_SEMICOLON) {
        unget_token();
    } else if ((decl_type = parse_type()) >= 0) {
        parse_local_variable(decl_type);
    } else {
        unget_token();
        parse_expr();
    }
    expect_token(TOKEN_SEMICOLON);
    reset_temp();
}

void parse_function(const char* name) {
    reset_local();
    int arg = 0;
    int args[8];
    while (1) {
        next_token();
        if (token_type == TOKEN_PAREN_RIGHT) {
            break;
        }
        if (token_type == TOKEN_ELLIPSIS) {
            expect_token(TOKEN_PAREN_RIGHT);
            break;
        }
        if (token_type == TOKEN_VOID) {
            if (arg != 0) {
                eprintf("void should be the only argument\n");
                exit(1);
            }
            expect_token(TOKEN_PAREN_RIGHT);
            break;
        }
        int arg_type = parse_type();
        if (arg_type < 0 || arg_type == TYPE_VOID) {
            eprintf("unexpected a non-void argument type: %d\n", arg_type);
            exit(1);
        }
        expect_token(TOKEN_ID);
        int arg_name = token_data;
        next_token();
        if (token_type == TOKEN_BRACKET_LEFT) {
            expect_token(TOKEN_BRACKET_RIGHT);
            next_token();
            if (arg_type & TYPE_PTR_MASK) {
                eprintf("local variable of array of pointers is not supported\n");
                exit(1);
            }
            arg_type = arg_type | TYPE_PTR_MASK;
        }
        args[arg++] = declare_local(token_data, arg_type);
        if (token_type == TOKEN_COMMA) {
            // continue;
        } else if (token_type == TOKEN_PAREN_RIGHT) {
            break;
        } else {
            eprintf("expecting ',' or ')'\n");
            exit(1);
        }
    }
    next_token();
    if (token_type == TOKEN_SEMICOLON) {
        return;
    }
    unget_token();
    expect_token(TOKEN_BRACE_LEFT);
    printf(".text\n");
    printf(".global %s\n", name);
    printf("%s:\n", name);
    int label = next_label();
    int prolog_label = next_label();
    epilog_label = next_label();
    asm_j(prolog_label);
    asm_label(label);
    while (1) {
        next_token();
        if (token_type == TOKEN_BRACE_RIGHT) {
            break;
        }
        unget_token();
        parse_stmt();
    }
    asm_j(epilog_label);
    int frame_size = max_local_id * 8;
    if (frame_size % 16 != 0) {
        frame_size = frame_size + 8;
    }
    // prolog
    asm_label(prolog_label);
    asm_addi("sp", "sp", -frame_size);
    asm_sd("ra", frame_size - 8, "sp");
    asm_sd("fp", frame_size - 16, "sp");
    for (int reg = REG_S2; reg <= REG_S11; ++reg) {
        asm_sd(reg_name(reg), frame_size - reg * 8 + 15 * 8, "sp");
    }
    asm_addi("fp", "sp", frame_size);
    for (int i = 0; i < arg; ++i) {
        int slot = args[i];
        load_local_address(REG_T2, slot);
        printf("  %s a%d, 0(t2)\n", store_op_of_type(local_type[slot]), i);
    }
    asm_j(label);
    // epilog
    asm_label(epilog_label);
    asm_ld("ra", frame_size - 8, "sp");
    asm_ld("fp", frame_size - 16, "sp");
    for (int reg = REG_S2; reg <= REG_S11; ++reg) {
        asm_ld(reg_name(reg), frame_size - reg * 8 + 15 * 8, "sp");
    }
    asm_addi("sp", "sp", frame_size);
    printf("  ret\n");
}

void parse_global_variable(int id, const char* name, int type) {
    if (type == TYPE_VOID) {
        eprintf("global variable of void type is not supported\n");
        exit(1);
    }
    if (type & TYPE_PTR_MASK) {
        eprintf("global variable of pointer is not supported\n");
        exit(1);
    }
    printf(".data\n");
    printf(".globl %s\n", name);
    printf(".align 5\n");
    printf("%s:\n", name);
    if (token_type == TOKEN_ASSIGN) {
        expect_token(TOKEN_NUMBER);
        printf("  .word %d\n", token_data);
    } else if (token_type == TOKEN_BRACKET_LEFT) {
        expect_token(TOKEN_NUMBER);
        int size = token_data;
        expect_token(TOKEN_BRACKET_RIGHT);
        int array_size = 4 * size;
        if (type == TYPE_CHAR) {
            array_size = size;
        }
        printf("  .zero %d\n", array_size);
        declare_global(id, MARKER_ARRAY, type);
    } else {
        printf("  .zero %d\n", 4);
        unget_token();
    }
    expect_token(TOKEN_SEMICOLON);
}

void parse_global_declaration() {
    int type = parse_type();
    if (type < 0) {
        eprintf("expecting type for global declaration\n");
        exit(1);
    }
    expect_token(TOKEN_ID);
    int id = token_data;
    char* name = id_table + id_lut[id];
    next_token();
    if (token_type == TOKEN_PAREN_LEFT) {
        declare_global(id, MARKER_FUNCTION, type); 
        parse_function(name);
    } else {
        declare_global(id, MARKER_SCALAR, type); 
        parse_global_variable(id, name, type);
    }
}

void parse_top_level() {
    next_token();
    if (token_type == TOKEN_EOF) 
        return;
    parse_global_declaration();
    parse_top_level();
}

void dump_string_table() {
    printf(".data\n");
    for (int i = 0; i < string_lut_size; ++i) {
        printf(".LC%d: .string \"", i);
        int offset = string_lut[i];
        int ch; 
        while ((ch = string_table[offset++]) != 0) {
            if (ch == '\n') {
                printf("\\n");
            } else if (ch == '\t') {
                printf("\\t");
            } else if (ch == '\r') {
                printf("\\r");
            } else if (ch == '\0') {
                printf("\\0");
            } else if (ch == '\\') {
                printf("\\\\");
            } else if (ch == '\'') {
                printf("\\'");
            } else if (ch == '\"') {
                printf("\\\"");
            } else {
                printf("%c", ch);
            }
        }
        printf("\"\n");
    }
}

int main() {
    eprintf("start compiling...\n");
    parse_top_level();
    dump_string_table();
    return 0;
}