#include "prcalc.h"
#include "prc_bits.h"

PRC_ERROR prc_init_context(prc_context *ctx) {
    
    ctx->registers.A = (uint64_t) 0;
    ctx->registers.B = (uint64_t) 0;
    ctx->registers.SP = (uint64_t) 0;
    ctx->registers.FLAGS = (uint64_t) 0;
    return OK;
}

PRC_ERROR prc_push(prc_context *ctx, uint64_t val) {
    if ( (ctx->registers.SP + 1) > STACK_SIZE ) {
        return STACK_OVERFLOW;
    }
    
    
    ctx->stack[ctx->registers.SP] = val;
    ctx->registers.SP +=1 ;
    return OK;
}

PRC_ERROR prc_pop(prc_context *ctx, uint64_t *val) {
    if ( ctx->registers.SP < 0 ) {
        return STACK_EMPTY;
    }
    
    ctx->registers.SP -= 1;
    *val = ctx->stack[ctx->registers.SP];
    return OK;
}

PRC_ERROR prc_set_a(prc_context *ctx, uint64_t val) {
    ctx->registers.A = val;
    return OK;
}

PRC_ERROR prc_set_b(prc_context *ctx, uint64_t val) {
    ctx->registers.B = val;
    return OK;
}

PRC_ERROR prc_swap(prc_context *ctx) {
    uint64_t *aux = malloc(sizeof( uint64_t));
    *aux = ctx->registers.A;
    if ( prc_push(ctx, ctx->registers.B) != OK ) {
        return STACK_OVERFLOW;
    }

    prc_set_b(ctx, *aux);
    if ( prc_pop(ctx, aux) != OK ) {
        return STATE_UNDEFINED;
    }
    prc_set_a(ctx, *aux);

    free(aux);
    return OK;
}

/* Add two values in the stack and save to register A */
PRC_ERROR prc_add_stack (prc_context *ctx) {
    uint64_t *aux1 = malloc(sizeof( uint64_t));
    uint64_t *aux2 = malloc(sizeof( uint64_t));
    


    if ( prc_pop(ctx, aux1) != OK ) 
        return STACK_EMPTY;
    
    if ( prc_pop(ctx, aux2) != OK ) 
        return STACK_EMPTY;


    ctx->registers.FLAGS &= 0b11111001;
    // 00100110
    // 11111001
    // 00000000

    ctx->registers.A = *aux1 + *aux2;

  if ( __test_overflow(*aux1, *aux2, ctx->registers.A, ADD) )
        ctx->registers.FLAGS |= OVERFLOW; 

  //ctx->registers.FLAGS = (__test_negative(ctx->registers.A) &  ~NEGATIVE) ;

    if (__test_negative(ctx->registers.A)) {
        ctx->registers.FLAGS |= NEGATIVE;
    }
  
    free(aux1);
    free(aux2);
    return OK;
}

/* Multiply two values in the stack and save to register A */
PRC_ERROR prc_mul_stack (prc_context *ctx) {
    uint64_t *aux1 = malloc(sizeof( uint64_t));
    uint64_t *aux2 = malloc(sizeof( uint64_t));

    ctx->registers.FLAGS &= 0b11111001;

    if ( prc_pop(ctx, aux1) != OK ) 
        return STACK_EMPTY;
     
    if ( prc_pop(ctx, aux2) != OK ) 
        return STACK_EMPTY;
    
    ctx->registers.A = *aux1 * *aux2;

    /*if ( __test_overflow(*aux1, *aux2, ctx->registers.A, MUL) ) 
        ctx->registers.FLAGS |= OVERFLOW;
 */
    if ( __test_negative(ctx->registers.A) )
        ctx->registers.FLAGS |= NEGATIVE; 
    
    free(aux1);
    free(aux2);
    return OK;
}

/* Subtract two values in the stack and save to register A */
PRC_ERROR SUB_STACK (prc_context *ctx) {
    uint64_t *aux1 = malloc(sizeof( uint64_t));
    uint64_t *aux2 = malloc(sizeof( uint64_t));

    if ( prc_pop(ctx, aux1) != OK ) 
        return STACK_EMPTY;
    
    if ( prc_pop(ctx, aux2) != OK ) 
        return STACK_EMPTY;
    ctx->registers.A = *aux1 - *aux2;

    if ( __test_negative(ctx->registers.A) )
        ctx->registers.FLAGS |= NEGATIVE;
    
    free(aux1);
    free(aux2);
    return OK;
}

/* Divide two values in the stack and save to register A */
PRC_ERROR DIV_STACK (prc_context *ctx) {
    uint64_t *aux = malloc(sizeof( uint64_t));
    if ( prc_pop(ctx, aux) != OK ) 
        return STACK_EMPTY;
    ctx->registers.A = *aux;
    if ( prc_pop(ctx, aux) != OK ) 
        return STACK_EMPTY;
    ctx->registers.A /= *aux;
    
    free(aux);
    return OK;
}

/* Divide two values in the stack and save to register A */
PRC_ERROR POW_STACK (prc_context *ctx) {
    uint64_t *aux = malloc( sizeof( uint64_t ) );
    uint64_t *power = malloc( sizeof( uint64_t ) );
    if ( prc_pop(ctx, power) != OK ) 
        return STACK_EMPTY;
    ctx->registers.A = *aux;
    
    if ( prc_pop(ctx, aux) != OK ) 
        return STACK_EMPTY;
    ctx->registers.A = pow(*aux, *power);
    
    free(aux);
    free(power);
    return OK;
}