#include "forth.h"
#include <stdarg.h>

static inline long syscall3(long n, long a1, long a2, long a3) {
    long ret;
    __asm__ volatile ("syscall"
        : "=a"(ret)
        : "a"(n), "D"(a1), "S"(a2), "d"(a3)
        : "rcx", "r11", "memory");
    return ret;
}

static inline long syscall1(long n, long a1) {
    long ret;
    __asm__ volatile ("syscall"
        : "=a"(ret)
        : "a"(n), "D"(a1)
        : "rcx", "r11", "memory");
    return ret;
}

void forth_putchar(char c) {
    char ch = c;
    syscall3(1, 1, (long)&ch, 1);
}

void forth_fflush(void) {
}

int forth_getchar(void) {
    unsigned char c;
    long n = syscall3(0, 0, (long)&c, 1);
    if (n <= 0) return FORTH_EOF;
    return (int)c;
}

void forth_panic(void) {
    syscall1(60, 1);
    __builtin_unreachable();
}

int64_t forth_strtoll(const char* str, char** endptr, int base) {
    const char* s = str;
    int neg = 0;
    int64_t val = 0;
    while (forth_isspace(*s)) s++;
    if (*s == '-') { neg = 1; s++; }
    else if (*s == '+') { s++; }
    while (*s >= '0' && *s <= '9') {
        val = val * base + (*s - '0');
        s++;
    }
    if (endptr) *endptr = (char*)s;
    return neg ? -val : val;
}

static void print_str(const char* s) {
    while (*s) forth_putchar(*s++);
}

static void print_int(long long v) {
    char buf[32];
    int i = 30;
    int neg = 0;
    if (v < 0) { neg = 1; v = -v; }
    buf[31] = '\0';
    if (v == 0) {
        buf[i--] = '0';
    } else {
        while (v > 0 && i >= 0) {
            buf[i--] = '0' + (v % 10);
            v /= 10;
        }
    }
    if (neg) buf[i--] = '-';
    print_str(&buf[i + 1]);
}

void forth_printf(const char* fmt, ...) {
    va_list ap;
    va_start(ap, fmt);
    while (*fmt) {
        if (*fmt == '%' && *(fmt + 1)) {
            fmt++;
            if (*fmt == 's') {
                print_str(va_arg(ap, const char*));
            } else if (*fmt == 'c') {
                forth_putchar((char)va_arg(ap, int));
            } else if (*fmt == '%') {
                forth_putchar('%');
            } else if (*fmt == 'l') {
                if (*(fmt + 1) == 'l' && (*(fmt + 2) == 'd' || *(fmt + 2) == 'i' || *(fmt + 2) == 'u')) {
                    fmt += 2;
                    print_int(va_arg(ap, long long));
                }
            } else if (*fmt == 'd' || *fmt == 'i' || *fmt == 'u') {
                print_int(va_arg(ap, int));
            } else {
                forth_putchar('%');
                forth_putchar(*fmt);
            }
        } else {
            forth_putchar(*fmt);
        }
        fmt++;
    }
    va_end(ap);
}

void _start(void) {
    forth_run();
    syscall1(60, 0);
    __builtin_unreachable();
}