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#include "prism/util/pm_integer.h"
/**
* Create a new node for an integer in the linked list.
*/
static pm_integer_word_t *
pm_integer_node_create(pm_integer_t *integer, uint32_t value) {
integer->length++;
pm_integer_word_t *node = malloc(sizeof(pm_integer_word_t));
if (node == NULL) return NULL;
*node = (pm_integer_word_t) { .next = NULL, .value = value };
return node;
}
/**
* Add a 32-bit integer to an integer.
*/
static void
pm_integer_add(pm_integer_t *integer, uint32_t addend) {
uint32_t carry = addend;
pm_integer_word_t *current = &integer->head;
while (carry > 0) {
uint64_t result = (uint64_t) current->value + carry;
carry = (uint32_t) (result >> 32);
current->value = (uint32_t) result;
if (carry > 0) {
if (current->next == NULL) {
current->next = pm_integer_node_create(integer, carry);
break;
}
current = current->next;
}
}
}
/**
* Multiple an integer by a 32-bit integer. In practice, the multiplier is the
* base of the integer, so this is 2, 8, 10, or 16.
*/
static void
pm_integer_multiply(pm_integer_t *integer, uint32_t multiplier) {
uint32_t carry = 0;
for (pm_integer_word_t *current = &integer->head; current != NULL; current = current->next) {
uint64_t result = (uint64_t) current->value * multiplier + carry;
carry = (uint32_t) (result >> 32);
current->value = (uint32_t) result;
if (carry > 0 && current->next == NULL) {
current->next = pm_integer_node_create(integer, carry);
break;
}
}
}
/**
* Return the value of a digit in a uint32_t.
*/
static uint32_t
pm_integer_parse_digit(const uint8_t character) {
switch (character) {
case '0': return 0;
case '1': return 1;
case '2': return 2;
case '3': return 3;
case '4': return 4;
case '5': return 5;
case '6': return 6;
case '7': return 7;
case '8': return 8;
case '9': return 9;
case 'a': case 'A': return 10;
case 'b': case 'B': return 11;
case 'c': case 'C': return 12;
case 'd': case 'D': return 13;
case 'e': case 'E': return 14;
case 'f': case 'F': return 15;
default: assert(false && "unreachable"); return 0;
}
}
/**
* 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.
*/
PRISM_EXPORTED_FUNCTION void
pm_integer_parse(pm_integer_t *integer, pm_integer_base_t base, const uint8_t *start, const uint8_t *end) {
// Ignore unary +. Unary + is parsed differently and will not end up here.
// Instead, it will modify the parsed integer later.
if (*start == '+') start++;
// Determine the multiplier from the base, and skip past any prefixes.
uint32_t multiplier = 10;
switch (base) {
case PM_INTEGER_BASE_BINARY:
start += 2; // 0b
multiplier = 2;
break;
case PM_INTEGER_BASE_OCTAL:
start++; // 0
if (*start == '_' || *start == 'o' || *start == 'O') start++; // o
multiplier = 8;
break;
case PM_INTEGER_BASE_DECIMAL:
if (*start == '0' && (end - start) > 1) start += 2; // 0d
break;
case PM_INTEGER_BASE_HEXADECIMAL:
start += 2; // 0x
multiplier = 16;
break;
case PM_INTEGER_BASE_UNKNOWN:
if (*start == '0' && (end - start) > 1) {
switch (start[1]) {
case '_': start += 2; multiplier = 8; break;
case '0': case '1': case '2': case '3': case '4': case '5': case '6': case '7': start++; multiplier = 8; break;
case 'b': case 'B': start += 2; multiplier = 2; break;
case 'o': case 'O': start += 2; multiplier = 8; break;
case 'd': case 'D': start += 2; break;
case 'x': case 'X': start += 2; multiplier = 16; break;
default: assert(false && "unreachable"); break;
}
}
break;
}
// It's possible that we've consumed everything at this point if there is an
// invalid integer. If this is the case, we'll just return 0.
if (start >= end) return;
// Add the first digit to the integer.
pm_integer_add(integer, pm_integer_parse_digit(*start++));
// Add the subsequent digits to the integer.
for (; start < end; start++) {
if (*start == '_') continue;
pm_integer_multiply(integer, multiplier);
pm_integer_add(integer, pm_integer_parse_digit(*start));
}
}
/**
* Return the memory size of the integer.
*/
size_t
pm_integer_memsize(const pm_integer_t *integer) {
return sizeof(pm_integer_t) + integer->length * sizeof(pm_integer_word_t);
}
/**
* 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) {
if (left->length < right->length) return -1;
if (left->length > right->length) return 1;
for (
const pm_integer_word_t *left_word = &left->head, *right_word = &right->head;
left_word != NULL && right_word != NULL;
left_word = left_word->next, right_word = right_word->next
) {
if (left_word->value < right_word->value) return -1;
if (left_word->value > right_word->value) return 1;
}
return 0;
}
/**
* Recursively destroy the linked list of an integer.
*/
static void
pm_integer_word_destroy(pm_integer_word_t *integer) {
if (integer->next != NULL) {
pm_integer_word_destroy(integer->next);
}
free(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.
*/
PRISM_EXPORTED_FUNCTION void
pm_integer_free(pm_integer_t *integer) {
if (integer->head.next) {
pm_integer_word_destroy(integer->head.next);
}
}
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