test-bits.c revision cbc01fc844fa307e565cc81fd78536d7afca05a9
9fe07780492524a34423686794bc1b4061206246Phil Carmody/* Copyright (c) 2001-2014 Dovecot authors, see the included COPYING file */
9fe07780492524a34423686794bc1b4061206246Phil Carmody
9fe07780492524a34423686794bc1b4061206246Phil Carmody/* Unit tests for bit twiddles library */
9fe07780492524a34423686794bc1b4061206246Phil Carmody
9fe07780492524a34423686794bc1b4061206246Phil Carmody#include "test-lib.h"
9fe07780492524a34423686794bc1b4061206246Phil Carmody
9fe07780492524a34423686794bc1b4061206246Phil Carmody#include <stdio.h>
9fe07780492524a34423686794bc1b4061206246Phil Carmody
9fe07780492524a34423686794bc1b4061206246Phil Carmody/* nearest_power(0) = error bits_requiredXX(0) = 0
9fe07780492524a34423686794bc1b4061206246Phil Carmody nearest_power(1) = 1 = 1<<0 bits_requiredXX(1) = 1
9fe07780492524a34423686794bc1b4061206246Phil Carmody nearest_power(2) = 2 = 1<<1 bits_requiredXX(2) = 2
9fe07780492524a34423686794bc1b4061206246Phil Carmody nearest_power(3) = 4 = 1<<2 bits_requiredXX(3) = 2
9fe07780492524a34423686794bc1b4061206246Phil Carmody nearest_power(4) = 4 = 1<<2 bits_requiredXX(4) = 3
9fe07780492524a34423686794bc1b4061206246Phil Carmody nearest_power(5) = 8 = 1<<3 bits_requiredXX(5) = 3
9fe07780492524a34423686794bc1b4061206246Phil Carmody nearest_power(7) = 8 = 1<<3 bits_requiredXX(7) = 3
9fe07780492524a34423686794bc1b4061206246Phil Carmody nearest_power(8) = 8 = 1<<3 bits_requiredXX(8) = 4
9fe07780492524a34423686794bc1b4061206246Phil Carmody*/
9fe07780492524a34423686794bc1b4061206246Phil Carmody
9fe07780492524a34423686794bc1b4061206246Phil Carmody/* nearest_power(num) == 1ULL << bits_required64(num-1) */
9fe07780492524a34423686794bc1b4061206246Phil Carmodystatic void test_nearest_power(void)
9fe07780492524a34423686794bc1b4061206246Phil Carmody{
9fe07780492524a34423686794bc1b4061206246Phil Carmody unsigned int b;
147dbf5e74344caf9baf4048999ce0e5419f9e51Phil Carmody size_t num;
9fe07780492524a34423686794bc1b4061206246Phil Carmody test_begin("nearest_power()");
9fe07780492524a34423686794bc1b4061206246Phil Carmody test_assert(nearest_power(1)==1);
9fe07780492524a34423686794bc1b4061206246Phil Carmody test_assert(nearest_power(2)==2);
147dbf5e74344caf9baf4048999ce0e5419f9e51Phil Carmody for (b = 2; b < CHAR_BIT*sizeof(size_t) - 1; ++b) {
147dbf5e74344caf9baf4048999ce0e5419f9e51Phil Carmody /* b=2 tests 3,4,5; b=3 tests 7,8,9; ... b=30 tests ~1G */
147dbf5e74344caf9baf4048999ce0e5419f9e51Phil Carmody num = (size_t)1 << b;
9fe07780492524a34423686794bc1b4061206246Phil Carmody test_assert_idx(nearest_power(num-1) == num, b);
9fe07780492524a34423686794bc1b4061206246Phil Carmody test_assert_idx(nearest_power(num ) == num, b);
9fe07780492524a34423686794bc1b4061206246Phil Carmody test_assert_idx(nearest_power(num+1) == num<<1, b);
9fe07780492524a34423686794bc1b4061206246Phil Carmody }
147dbf5e74344caf9baf4048999ce0e5419f9e51Phil Carmody /* With 32-bit size_t, now: b=31 tests 2G-1, 2G, not 2G+1. */
147dbf5e74344caf9baf4048999ce0e5419f9e51Phil Carmody num = (size_t)1 << b;
147dbf5e74344caf9baf4048999ce0e5419f9e51Phil Carmody test_assert_idx(nearest_power(num-1) == num, b);
147dbf5e74344caf9baf4048999ce0e5419f9e51Phil Carmody test_assert_idx(nearest_power(num ) == num, b);
147dbf5e74344caf9baf4048999ce0e5419f9e51Phil Carmody /* i_assert()s: test_assert_idx(nearest_power(num+1) == num<<1, b); */
9fe07780492524a34423686794bc1b4061206246Phil Carmody test_end();
9fe07780492524a34423686794bc1b4061206246Phil Carmody}
9fe07780492524a34423686794bc1b4061206246Phil Carmody
9fe07780492524a34423686794bc1b4061206246Phil Carmodystatic void test_bits_requiredXX(void)
9fe07780492524a34423686794bc1b4061206246Phil Carmody{
9fe07780492524a34423686794bc1b4061206246Phil Carmody /* As ..64 depends on ..32 and tests it twice,
9fe07780492524a34423686794bc1b4061206246Phil Carmody * and ..32 depends on ..16 and tests it twice,
9fe07780492524a34423686794bc1b4061206246Phil Carmody * etc., we only test ..64
9fe07780492524a34423686794bc1b4061206246Phil Carmody */
9fe07780492524a34423686794bc1b4061206246Phil Carmody unsigned int b;
9fe07780492524a34423686794bc1b4061206246Phil Carmody test_begin("bits_requiredXX()");
9fe07780492524a34423686794bc1b4061206246Phil Carmody test_assert(bits_required64(0) == 0);
9fe07780492524a34423686794bc1b4061206246Phil Carmody test_assert(bits_required64(1) == 1);
9fe07780492524a34423686794bc1b4061206246Phil Carmody test_assert(bits_required64(2) == 2);
9fe07780492524a34423686794bc1b4061206246Phil Carmody for (b = 2; b < 64; ++b) {
9fe07780492524a34423686794bc1b4061206246Phil Carmody /* b=2 tests 3,4,5; b=3 tests 7,8,9; ... */
9fe07780492524a34423686794bc1b4061206246Phil Carmody uint64_t num = 1ULL << b;
9fe07780492524a34423686794bc1b4061206246Phil Carmody test_assert_idx(bits_required64(num-1) == b, b);
9fe07780492524a34423686794bc1b4061206246Phil Carmody test_assert_idx(bits_required64(num ) == b+1, b);
9fe07780492524a34423686794bc1b4061206246Phil Carmody test_assert_idx(bits_required64(num+1) == b+1, b);
9fe07780492524a34423686794bc1b4061206246Phil Carmody }
9fe07780492524a34423686794bc1b4061206246Phil Carmody test_end();
9fe07780492524a34423686794bc1b4061206246Phil Carmody}
9fe07780492524a34423686794bc1b4061206246Phil Carmody
cbc01fc844fa307e565cc81fd78536d7afca05a9Timo Sirainenstatic void test_sum_overflows(void)
cbc01fc844fa307e565cc81fd78536d7afca05a9Timo Sirainen{
cbc01fc844fa307e565cc81fd78536d7afca05a9Timo Sirainen#define MAX64 (uint64_t)-1
cbc01fc844fa307e565cc81fd78536d7afca05a9Timo Sirainen static const struct {
cbc01fc844fa307e565cc81fd78536d7afca05a9Timo Sirainen uint64_t a, b;
cbc01fc844fa307e565cc81fd78536d7afca05a9Timo Sirainen bool overflows;
cbc01fc844fa307e565cc81fd78536d7afca05a9Timo Sirainen } tests[] = {
cbc01fc844fa307e565cc81fd78536d7afca05a9Timo Sirainen { MAX64-1, 1, FALSE },
cbc01fc844fa307e565cc81fd78536d7afca05a9Timo Sirainen { MAX64, 1, TRUE },
cbc01fc844fa307e565cc81fd78536d7afca05a9Timo Sirainen { MAX64-1, 1, FALSE },
cbc01fc844fa307e565cc81fd78536d7afca05a9Timo Sirainen { MAX64-1, 2, TRUE },
cbc01fc844fa307e565cc81fd78536d7afca05a9Timo Sirainen { MAX64-1, MAX64-1, TRUE },
cbc01fc844fa307e565cc81fd78536d7afca05a9Timo Sirainen { MAX64-1, MAX64, TRUE },
cbc01fc844fa307e565cc81fd78536d7afca05a9Timo Sirainen { MAX64, MAX64, TRUE }
cbc01fc844fa307e565cc81fd78536d7afca05a9Timo Sirainen };
cbc01fc844fa307e565cc81fd78536d7afca05a9Timo Sirainen unsigned int i;
cbc01fc844fa307e565cc81fd78536d7afca05a9Timo Sirainen
cbc01fc844fa307e565cc81fd78536d7afca05a9Timo Sirainen test_begin("UINT64_SUM_OVERFLOWS");
cbc01fc844fa307e565cc81fd78536d7afca05a9Timo Sirainen for (i = 0; i < N_ELEMENTS(tests); i++)
cbc01fc844fa307e565cc81fd78536d7afca05a9Timo Sirainen test_assert(UINT64_SUM_OVERFLOWS(tests[i].a, tests[i].b) == tests[i].overflows);
cbc01fc844fa307e565cc81fd78536d7afca05a9Timo Sirainen test_end();
cbc01fc844fa307e565cc81fd78536d7afca05a9Timo Sirainen}
cbc01fc844fa307e565cc81fd78536d7afca05a9Timo Sirainen
9fe07780492524a34423686794bc1b4061206246Phil Carmodyvoid test_bits()
9fe07780492524a34423686794bc1b4061206246Phil Carmody{
9fe07780492524a34423686794bc1b4061206246Phil Carmody test_nearest_power();
9fe07780492524a34423686794bc1b4061206246Phil Carmody test_bits_requiredXX();
cbc01fc844fa307e565cc81fd78536d7afca05a9Timo Sirainen test_sum_overflows();
9fe07780492524a34423686794bc1b4061206246Phil Carmody}