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// Tests divlu and divllu, intended for use with AFL.
// This aborts on error.
// To build:
// clang divlu_fuzz_driver.cpp divlu.c
#include <limits.h>
#include <stdint.h>
#include <stdlib.h>
#include <stdio.h>
extern "C" {
uint32_t divlu(uint32_t numhi, uint32_t numlo, uint32_t den, uint32_t *r);
uint64_t divllu(uint64_t numhi, uint64_t numlo, uint64_t den, uint64_t *r);
}
// Read one uint64.
static uint64_t read1() {
unsigned long long res = UINT64_MAX;
// We may read either raw bytes (faster fuzzing)
// or text (slower fuzzing but easier to understand test cases).
bool raw_bytes = true;
if (raw_bytes) {
if (fread(&res, sizeof res, 1, stdin) != 1) {
exit(EXIT_FAILURE);
}
} else {
if (scanf(" %llu ", &res) != 1) {
exit(EXIT_FAILURE);
}
}
return res;
}
static void test64(uint64_t numhi, uint64_t numlo, uint64_t denom) {
typedef unsigned long long ullong;
uint64_t rem;
uint64_t quot = divllu(numhi, numlo, denom, &rem);
uint64_t expected_rem;
uint64_t expected_quot;
if (numhi >= denom) {
expected_rem = UINT64_MAX;
expected_quot = UINT64_MAX;
} else {
__uint128_t num = (__uint128_t(numhi) << 64) | numlo;
expected_quot = num / denom;
expected_rem = num % denom;
}
if (expected_quot != quot) {
fprintf(stderr, "divllu: %llu %llu / %llu -> got %llu, expected %llu\n", ullong(numhi),
ullong(numlo), ullong(denom), ullong(quot), ullong(expected_quot));
abort();
}
if (expected_rem != rem) {
fprintf(stderr, "divllu: %llu %llu %% %llu -> got %llu, expected %llu\n", ullong(numhi),
ullong(numlo), ullong(denom), ullong(rem), ullong(expected_rem));
abort();
}
}
static void test32(uint32_t numhi, uint32_t numlo, uint32_t denom) {
typedef unsigned long long ullong;
uint32_t rem;
uint32_t quot = divlu(numhi, numlo, denom, &rem);
uint32_t expected_rem;
uint32_t expected_quot;
if (numhi >= denom) {
expected_rem = UINT32_MAX;
expected_quot = UINT32_MAX;
} else {
uint64_t num = (uint64_t(numhi) << 32) | numlo;
expected_quot = num / denom;
expected_rem = num % denom;
}
if (expected_quot != quot) {
fprintf(stderr, "divlu: %llu %llu / %llu -> got %llu, expected %llu\n", ullong(numhi),
ullong(numlo), ullong(denom), ullong(quot), ullong(expected_quot));
abort();
}
if (expected_rem != rem) {
fprintf(stderr, "divlu: %llu %llu %% %llu -> got %llu, expected %llu\n", ullong(numhi),
ullong(numlo), ullong(denom), ullong(rem), ullong(expected_rem));
abort();
}
}
int main(void) {
uint64_t denom = read1();
for (;;) {
uint64_t numlo = read1();
uint64_t numhi = read1();
test32((uint32_t)numhi, (uint32_t)numlo, (uint32_t)denom);
test64(numhi, numlo, denom);
}
}
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