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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Gerrit-Project: libosmocore
Gerrit-Branch: master
Gerrit-Change-Id: If61cd54f43643325c45f64531c57fe4c5802a9cf
Gerrit-Change-Number: 30933
Gerrit-PatchSet: 1
Gerrit-Owner: dexter <[email protected]>
Gerrit-MessageType: newchange
