1 files changed, 126 insertions, 0 deletions
diff --git a/prism/util/pm_integer.h b/prism/util/pm_integer.h
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+++ b/prism/util/pm_integer.h
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+/**
+ * @file pm_integer.h
+ *
+ * This module provides functions for working with arbitrary-sized integers.
+ */
+#ifndef PRISM_NUMBER_H
+#define PRISM_NUMBER_H
+
+#include "prism/defines.h"
+#include "prism/util/pm_buffer.h"
+
+#include <assert.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+/**
+ * A structure represents an arbitrary-sized integer.
+ */
+typedef struct {
+    /**
+     * The number of allocated values. length is set to 0 if the integer fits
+     * into uint32_t.
+     */
+    size_t length;
+
+    /**
+     * List of 32-bit integers. Set to NULL if the integer fits into uint32_t.
+     */
+    uint32_t *values;
+
+    /**
+     * Embedded value for small integer. This value is set to 0 if the value
+     * does not fit into uint32_t.
+     */
+    uint32_t value;
+
+    /**
+     * Whether or not the integer is negative. It is stored this way so that a
+     * zeroed pm_integer_t is always positive zero.
+     */
+    bool negative;
+} pm_integer_t;
+
+/**
+ * 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.
+ *
+ * @param integer The integer to parse into.
+ * @param base The base of the integer.
+ * @param start The start of the string.
+ * @param end The end of the string.
+ */
+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.
+ *
+ * @param left The left integer to compare.
+ * @param right The right integer to compare.
+ * @return The result of the comparison.
+ */
+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.
+ *
+ * @param numerator The numerator of the ratio.
+ * @param denominator The denominator of the ratio.
+ */
+void pm_integers_reduce(pm_integer_t *numerator, pm_integer_t *denominator);
+
+/**
+ * Convert an integer to a decimal string.
+ *
+ * @param buffer The buffer to append the string to.
+ * @param integer The integer to convert to a string.
+ */
+PRISM_EXPORTED_FUNCTION void pm_integer_string(pm_buffer_t *buffer, const pm_integer_t *integer);
+
+/**
+ * Free the internal memory of an integer. This memory will only be allocated if
+ * the integer exceeds the size of a single node in the linked list.
+ *
+ * @param integer The integer to free.
+ */
+PRISM_EXPORTED_FUNCTION void pm_integer_free(pm_integer_t *integer);
+
+#endif