comp1521/smips/helper.c


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#include "helper.h"

// Returns the n'th bit of a uint32_t value.
uint32_t get_nth_bit(const uint32_t value, const int n) {
    return (value & (1u << n)) >> n;
}

// Prints the bits of a uint32_t value.
void print_bits(const uint32_t value) {
    for (int i = (int)sizeof(uint32_t)*8-1; i >= 0; --i) {
        printf("%d", get_nth_bit(value, i));
    }
    printf("\n");
}

// Skips past the next newline. 
// If EOF, stays on EOF so that subsequent fgetc() calls return EOF.
void skip_past_newline(FILE *const fptr) {
    int c = 0;
    c = fgetc(fptr);
    while (true) {
        if (c == EOF) {
            fseek(fptr, -1L, SEEK_CUR);
            return;
        }
        else if (c == '\n') {
            printf("newline\n");
            return;
        } else {
            fseek(fptr, -1L, SEEK_CUR);
            return;
        }
        printf("skipping char\n");
        c = fgetc(fptr);
    }
}

// Converts decimal values to hex obviously.
uint32_t hex_to_decimal(const uint32_t decimal) {
    uint32_t ret = 0;
    for (size_t i = 0; i < sizeof(uint32_t); ++i) { // Iterate through 4 bytes.
        uint32_t tmp = (decimal & (0xFFu << 8*i)) >> 8*i;
        if (isalpha(tmp)) {
            tmp -= 'a';
            tmp += 10;
        }
        else if (isdigit(tmp)) {
            tmp -= '0';
        } 
        // There should be no other cases if the input is hex.
        ret |= (tmp << 4*i);
    }
    return ret;
}