integer.h

/*
 * This module provides functions for working with arbitrary-sized integers.
 */
#ifndef PRISM_INTERNAL_INTEGER_H
#define PRISM_INTERNAL_INTEGER_H
 
#include "prism/buffer.h"
#include "prism/integer.h"
 
#include <stdint.h>
 
/*
 * An enum controlling the base of an integer. It is expected that the base is
 * already known before parsing the integer, even though it could be derived
 * from the string itself.
 */
typedef enum {
    /* The default decimal base, with no prefix. Leading 0s will be ignored. */
    PM_INTEGER_BASE_DEFAULT,
 
    /* The binary base, indicated by a 0b or 0B prefix. */
    PM_INTEGER_BASE_BINARY,
 
    /* The octal base, indicated by a 0, 0o, or 0O prefix. */
    PM_INTEGER_BASE_OCTAL,
 
    /* The decimal base, indicated by a 0d, 0D, or empty prefix. */
    PM_INTEGER_BASE_DECIMAL,
 
    /* The hexadecimal base, indicated by a 0x or 0X prefix. */
    PM_INTEGER_BASE_HEXADECIMAL,
 
    /*
     * An unknown base, in which case pm_integer_parse will derive it based on
     * the content of the string. This is less efficient and does more
     * comparisons, so if callers know the base ahead of time, they should use
     * that instead.
     */
    PM_INTEGER_BASE_UNKNOWN
} pm_integer_base_t;
 
/*
 * Parse an integer from a string. This assumes that the format of the integer
 * has already been validated, as internal validation checks are not performed
 * here.
 */
void pm_integer_parse(pm_integer_t *integer, pm_integer_base_t base, const uint8_t *start, const uint8_t *end);
 
/*
 * Compare two integers. This function returns -1 if the left integer is less
 * than the right integer, 0 if they are equal, and 1 if the left integer is
 * greater than the right integer.
 */
int pm_integer_compare(const pm_integer_t *left, const pm_integer_t *right);
 
/*
 * Reduce a ratio of integers to its simplest form.
 *
 * If either the numerator or denominator do not fit into a 32-bit integer, then
 * this function is a no-op. In the future, we may consider reducing even the
 * larger numbers, but for now we're going to keep it simple.
 */
void pm_integers_reduce(pm_integer_t *numerator, pm_integer_t *denominator);
 
/* Convert an integer to a decimal string. */
void pm_integer_string(pm_buffer_t *buffer, const pm_integer_t *integer);
 
#endif