dexter has uploaded this change for review. ( https://gerrit.osmocom.org/c/libosmocore/+/30933 )
Change subject: uitils: add floored and euclidian modulo functions ......................................................................
uitils: add floored and euclidian modulo functions
C/C++ only implements a so called "truncated modulo" function. Lets also add a floored and an euclidian modulo function to be more complete.
Change-Id: If61cd54f43643325c45f64531c57fe4c5802a9cf --- M include/osmocom/core/utils.h M tests/utils/utils_test.c M tests/utils/utils_test.ok 3 files changed, 102 insertions(+), 0 deletions(-)
git pull ssh://gerrit.osmocom.org:29418/libosmocore refs/changes/33/30933/1
diff --git a/include/osmocom/core/utils.h b/include/osmocom/core/utils.h index d0e2e9b..5623552 100644 --- a/include/osmocom/core/utils.h +++ b/include/osmocom/core/utils.h @@ -182,6 +182,18 @@
uint32_t osmo_isqrt32(uint32_t x);
+/*! Floored Modulo (See also: Daan Leijen, Division and Modulus for Computer Scientists). + * \param[in] x dividend. + * \param[in] y divisor. + * \returns remainder of x divided by y. */ +#define OSMO_MOD_FLR(x, y) (x > 0 && y < 0 || x < 0 && y > 0 ? x % y + y : x % y) + +/*! Euclidean Modulo (See also: Daan Leijen, Division and Modulus for Computer Scientists). + * \param[in] x dividend. + * \param[in] y divisor. + * \returns remainder of x divided by y. */ +#define OSMO_MOD_EUC(x, y) (x % y < 0 ? y > 0 ? x % y + y : x % y - y : x % y) + char osmo_luhn(const char* in, int in_len);
/*! State for OSMO_STRBUF_APPEND() and OSMO_STRBUF_PRINTF(). See there for examples. */ diff --git a/tests/utils/utils_test.c b/tests/utils/utils_test.c index 9ddae65..79030f9 100644 --- a/tests/utils/utils_test.c +++ b/tests/utils/utils_test.c @@ -766,6 +766,65 @@ } }
+static void mod_test_mod(int x, int y, int expected_result) +{ + int result; + result = x % y; + printf(" %i mod %i = %i = %i\n", x, y, result, expected_result); + OSMO_ASSERT(result == expected_result); +} + +static void mod_test_mod_flr(int x, int y, int expected_result) +{ + int result; + result = OSMO_MOD_FLR(x, y); + printf(" %i mod_flr %i = %i = %i\n", x, y, result, expected_result); + OSMO_ASSERT(result == expected_result); +} + +static void mod_test_mod_euc(int x, int y, int expected_result) +{ + int result; + result = OSMO_MOD_EUC(x, y); + printf(" %i mod_euc %i = %i = %i\n", x, y, result, expected_result); + OSMO_ASSERT(result == expected_result); +} + +static void mod_test(void) +{ + /* See also: Daan Leijen, Division and Modulus for Computer + * Scientists, section 1.3 */ + + printf("\nTesting built in truncated modulo for comparison:\n"); + mod_test_mod(8, 3, 2); + mod_test_mod(8, -3, 2); + mod_test_mod(-8, 3, -2); + mod_test_mod(-8, -3, -2); + mod_test_mod(1, 2, 1); + mod_test_mod(1, -2, 1); + mod_test_mod(-1, 2, -1); + mod_test_mod(-1, -2, -1); + + printf("\nTesting OSMO_MOD_FLR():\n"); + mod_test_mod_flr(8, 3, 2); + mod_test_mod_flr(8, -3, -1); + mod_test_mod_flr(-8, 3, 1); + mod_test_mod_flr(-8, -3, -2); + mod_test_mod_flr(1, 2, 1); + mod_test_mod_flr(1, -2, -1); + mod_test_mod_flr(-1, 2, 1); + mod_test_mod_flr(-1, -2, -1); + + printf("\nTesting OSMO_MOD_EUC():\n"); + mod_test_mod_euc(8, 3, 2); + mod_test_mod_euc(8, -3, 2); + mod_test_mod_euc(-8, 3, 1); + mod_test_mod_euc(-8, -3, 1); + mod_test_mod_euc(1, 2, 1); + mod_test_mod_euc(1, -2, 1); + mod_test_mod_euc(-1, 2, 1); + mod_test_mod_euc(-1, -2, 1); +}
struct osmo_sockaddr_to_str_and_uint_test_case { uint16_t port; @@ -2088,6 +2147,7 @@ str_escape3_test(); str_quote3_test(); isqrt_test(); + mod_test(); osmo_sockaddr_to_str_and_uint_test(); osmo_str_tolowupper_test(); strbuf_test(); diff --git a/tests/utils/utils_test.ok b/tests/utils/utils_test.ok index 1409d81..3f453e9 100644 --- a/tests/utils/utils_test.ok +++ b/tests/utils/utils_test.ok @@ -354,6 +354,36 @@
Testing integer square-root
+Testing built in truncated modulo for comparison: + 8 mod 3 = 2 = 2 + 8 mod -3 = 2 = 2 + -8 mod 3 = -2 = -2 + -8 mod -3 = -2 = -2 + 1 mod 2 = 1 = 1 + 1 mod -2 = 1 = 1 + -1 mod 2 = -1 = -1 + -1 mod -2 = -1 = -1 + +Testing OSMO_MOD_FLR(): + 8 mod_flr 3 = 2 = 2 + 8 mod_flr -3 = -1 = -1 + -8 mod_flr 3 = 1 = 1 + -8 mod_flr -3 = -2 = -2 + 1 mod_flr 2 = 1 = 1 + 1 mod_flr -2 = -1 = -1 + -1 mod_flr 2 = 1 = 1 + -1 mod_flr -2 = -1 = -1 + +Testing OSMO_MOD_EUC(): + 8 mod_euc 3 = 2 = 2 + 8 mod_euc -3 = 2 = 2 + -8 mod_euc 3 = 1 = 1 + -8 mod_euc -3 = 1 = 1 + 1 mod_euc 2 = 1 = 1 + 1 mod_euc -2 = 1 = 1 + -1 mod_euc 2 = 1 = 1 + -1 mod_euc -2 = 1 = 1 + osmo_sockaddr_to_str_and_uint_test [0] [0.0.0.0]:0 addr_len=20 --> [0.0.0.0]:0 rc=7 [1] [255.255.255.255]:65535 addr_len=20 --> [255.255.255.255]:65535 rc=15
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dexter