#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <stdint.h>
#include <stdbool.h>

#include "uforth_opcodes.h"

#define BFORTH_PGM_SIZE  (1024)
#define BFORTH_STACK_SIZE  (64)
#define BFORTH_RSTACK_SIZE  (32)

const uint8_t * bf_prog = NULL;
uint16_t bf_prog_len = 0;

const uint8_t * bfdict[26];
uint8_t bfvars[26];
uint8_t bf_stack[BFORTH_STACK_SIZE];
uint8_t * bf_stacktop;
const uint8_t * bf_linkstack[BFORTH_RSTACK_SIZE];
const uint8_t ** bf_linkstacktop;
const uint8_t * bf_pc;


#define DSTKPUSH(x)  (*(bf_stacktop++) = x)
#define DSTKPOP    (*(--bf_stacktop))
#define DSTKTOP    (*(bf_stacktop - 1))
#define DSTKIDX(i)   (*(bf_stacktop - 1 - i))
void BF_Step(void)
{
    if(*bf_pc == '\0')
        return;
    
    uint8_t tmp = *bf_pc++;
    printf("op: 0x%02X\n", tmp);
    switch(tmp) {
        case OPCODE_ADD: tmp = DSTKPOP; DSTKTOP += tmp; break;
        case OPCODE_SUB: tmp = DSTKPOP; DSTKTOP -= tmp; break;
        case OPCODE_MUL: tmp = DSTKPOP; DSTKTOP *= tmp; break;
        case OPCODE_DIV: tmp = DSTKPOP; DSTKTOP /= tmp; break;
        case OPCODE_BITXOR: tmp = DSTKPOP; DSTKTOP ^= tmp; break;
        case OPCODE_BITAND: tmp = DSTKPOP; DSTKTOP &= tmp; break;
        case OPCODE_BITOR: tmp = DSTKPOP; DSTKTOP |= tmp; break;
        
        case OPCODE_LT: tmp = DSTKPOP; DSTKTOP = DSTKTOP < tmp; break;
        case OPCODE_GT: tmp = DSTKPOP; DSTKTOP = DSTKTOP > tmp; break;
        case OPCODE_EQ: tmp = DSTKPOP; DSTKTOP = DSTKTOP == tmp; break;
        
        case OPCODE_PUSH: DSTKPUSH(*bf_pc++); break;
        case OPCODE_POP: DSTKPOP; break;
        // case OPCODE_DUP: tmp = DSTKTOP; DSTKPUSH(tmp); break;
        // case OPCODE_SWAP: tmp = DSTKIDX(0); DSTKIDX(0) = DSTKIDX(1); DSTKIDX(1) = tmp; break;
        
        case OPCODE_DEF:
            tmp = bf_pc[0];
            bfdict[tmp] = bf_pc + 2;
            bf_pc += bf_pc[1];
        break;
        
        case OPCODE_CALL:
            *bf_linkstacktop++ = bf_pc;
            bf_pc = bfdict[bf_pc[0]];
        break;
        
        case OPCODE_RET:// End definition/return
            bf_pc = *(--bf_linkstacktop);
        break;
        
        case OPCODE_CJMP_F:
            if(!DSTKPOP)
                bf_pc += bf_pc[0];
        break;
        
        case OPCODE_JMP:
            bf_pc += bf_pc[0];
        break;
        
        case OPCODE_PRINT: printf("0x%02X\n", DSTKPOP); break;
        // case '.': printf("%d\n", DSTKPOP); break;
        // case '.': printf("%c", DSTKPOP); break;
        
        case OPCODE_RESET_STACKS:
            bf_stacktop = bf_stack;
            bf_linkstacktop = bf_linkstack;
        break;
    }
}


void BF_Run(const uint8_t * src, uint16_t len)
{
    bf_prog = src;
    bf_prog_len = len;
    bf_stacktop = bf_stack;
    bf_linkstacktop = bf_linkstack;
    bf_pc = src;
    while(*bf_pc)
    {
        BF_Step();
        printf("pc: %d ", (int)(bf_pc - bf_prog));
        printf("stk: %d ", (int)(bf_stacktop - bf_stack));
        printf("lstk: %d\n", (int)(bf_linkstacktop - bf_linkstack));
    }
}


int main(int argc, const char * argv[])
{
    FILE * fin = fopen( "microforthtest.bin" , "r" );
    fseek(fin, 0, SEEK_END);
    size_t len = ftell(fin);
    fseek(fin, 0, SEEK_SET);
    uint8_t * prog = (uint8_t *)malloc(len);
    fread(prog, 1, len, fin);
    fclose(fin);
    
    printf("Program size: %d B\n", (int)len);
    
    BF_Run(prog, len);
}