Add octet-aligned/unaligned shift functions

The actual code is from OsmoBTS' tch.c by Harald Welte. Add unit tests,
doxygen annotation and extra memory safety check. Those functions are
used in several BTS implementations but seems generic enough to be
generally useful.

Change-Id: I2b1901c4161e8035f059585901dca593b661556d

2 files changed, 130 insertions, 0 deletions

diff --git a/tests/bits/bitrev_test.c b/tests/bits/bitrev_test.c
index 987f4d51..08f08278 100644
--- a/tests/bits/bitrev_test.c
+++ b/tests/bits/bitrev_test.c
@@ -205,6 +205,20 @@ check16(uint16_t test, enum END e)
 	printcheck16(e, test, test, (BE == e) ? s : NULL, print);
 }
 
+static void sh_chk(const uint8_t *in, uint8_t len, unsigned int nib, bool r)
+{
+	uint8_t x[len];
+	if (r)
+		osmo_nibble_shift_right(x, in, nib);
+	else
+		osmo_nibble_shift_left_unal(x, in, nib);
+
+	printf("[%u] %s IN: %s, nibble %u:", len, r ? "R" : "L",
+	       osmo_hexdump_nospc(in, len), nib);
+	/* do NOT combine those printfs: osmo_hexdump* use static buffer which
+	   WILL screw things up in that case */
+	printf("\n     OUT: %s\n", osmo_hexdump_nospc(x, nib/2));
+}
 
 int main(int argc, char **argv)
 {
@@ -274,5 +288,16 @@ int main(int argc, char **argv)
 	check16(0, BE);
 	check16(0, LE);
 
+	printf("running nibble tests...\n");
+
+	const uint8_t in1[] = { 0xF0, 0x0D, 0xCA, 0xFE, 0xDE, 0xAD, 0xBE, 0xEF },
+		      in2[] = { 0xB0, 0x0B, 0xBA, 0xBE, 0xFA, 0xCE };
+
+	for (offs = 0; offs < 13; offs++) {
+		sh_chk(in1, ARRAY_SIZE(in1), offs, true);
+		sh_chk(in1, ARRAY_SIZE(in1), offs, false);
+		sh_chk(in2, ARRAY_SIZE(in2), offs, true);
+		sh_chk(in2, ARRAY_SIZE(in2), offs, false);
+	}
 	return 0;
 }
diff --git a/tests/bits/bitrev_test.ok b/tests/bits/bitrev_test.ok
index 90cb295f..9fbb4d9c 100644
--- a/tests/bits/bitrev_test.ok
+++ b/tests/bits/bitrev_test.ok
@@ -53,3 +53,108 @@ running random tests...
 24 LE OK
 16 BE OK, storage OK
 16 LE OK
+running nibble tests...
+[8] R IN: f00dcafedeadbeef, nibble 0:
+     OUT: 
+[8] L IN: f00dcafedeadbeef, nibble 0:
+     OUT: 
+[6] R IN: b00bbabeface, nibble 0:
+     OUT: 
+[6] L IN: b00bbabeface, nibble 0:
+     OUT: 
+[8] R IN: f00dcafedeadbeef, nibble 1:
+     OUT: 
+[8] L IN: f00dcafedeadbeef, nibble 1:
+     OUT: 
+[6] R IN: b00bbabeface, nibble 1:
+     OUT: 
+[6] L IN: b00bbabeface, nibble 1:
+     OUT: 
+[8] R IN: f00dcafedeadbeef, nibble 2:
+     OUT: 0f
+[8] L IN: f00dcafedeadbeef, nibble 2:
+     OUT: 00
+[6] R IN: b00bbabeface, nibble 2:
+     OUT: 0b
+[6] L IN: b00bbabeface, nibble 2:
+     OUT: 00
+[8] R IN: f00dcafedeadbeef, nibble 3:
+     OUT: 0f
+[8] L IN: f00dcafedeadbeef, nibble 3:
+     OUT: 00
+[6] R IN: b00bbabeface, nibble 3:
+     OUT: 0b
+[6] L IN: b00bbabeface, nibble 3:
+     OUT: 00
+[8] R IN: f00dcafedeadbeef, nibble 4:
+     OUT: 0f00
+[8] L IN: f00dcafedeadbeef, nibble 4:
+     OUT: 00dc
+[6] R IN: b00bbabeface, nibble 4:
+     OUT: 0b00
+[6] L IN: b00bbabeface, nibble 4:
+     OUT: 00bb
+[8] R IN: f00dcafedeadbeef, nibble 5:
+     OUT: 0f00
+[8] L IN: f00dcafedeadbeef, nibble 5:
+     OUT: 00dc
+[6] R IN: b00bbabeface, nibble 5:
+     OUT: 0b00
+[6] L IN: b00bbabeface, nibble 5:
+     OUT: 00bb
+[8] R IN: f00dcafedeadbeef, nibble 6:
+     OUT: 0f00dc
+[8] L IN: f00dcafedeadbeef, nibble 6:
+     OUT: 00dcaf
+[6] R IN: b00bbabeface, nibble 6:
+     OUT: 0b00bb
+[6] L IN: b00bbabeface, nibble 6:
+     OUT: 00bbab
+[8] R IN: f00dcafedeadbeef, nibble 7:
+     OUT: 0f00dc
+[8] L IN: f00dcafedeadbeef, nibble 7:
+     OUT: 00dcaf
+[6] R IN: b00bbabeface, nibble 7:
+     OUT: 0b00bb
+[6] L IN: b00bbabeface, nibble 7:
+     OUT: 00bbab
+[8] R IN: f00dcafedeadbeef, nibble 8:
+     OUT: 0f00dcaf
+[8] L IN: f00dcafedeadbeef, nibble 8:
+     OUT: 00dcafed
+[6] R IN: b00bbabeface, nibble 8:
+     OUT: 0b00bbab
+[6] L IN: b00bbabeface, nibble 8:
+     OUT: 00bbabef
+[8] R IN: f00dcafedeadbeef, nibble 9:
+     OUT: 0f00dcaf
+[8] L IN: f00dcafedeadbeef, nibble 9:
+     OUT: 00dcafed
+[6] R IN: b00bbabeface, nibble 9:
+     OUT: 0b00bbab
+[6] L IN: b00bbabeface, nibble 9:
+     OUT: 00bbabef
+[8] R IN: f00dcafedeadbeef, nibble 10:
+     OUT: 0f00dcafed
+[8] L IN: f00dcafedeadbeef, nibble 10:
+     OUT: 00dcafedea
+[6] R IN: b00bbabeface, nibble 10:
+     OUT: 0b00bbabef
+[6] L IN: b00bbabeface, nibble 10:
+     OUT: 00bbabefac
+[8] R IN: f00dcafedeadbeef, nibble 11:
+     OUT: 0f00dcafed
+[8] L IN: f00dcafedeadbeef, nibble 11:
+     OUT: 00dcafedea
+[6] R IN: b00bbabeface, nibble 11:
+     OUT: 0b00bbabef
+[6] L IN: b00bbabeface, nibble 11:
+     OUT: 00bbabefac
+[8] R IN: f00dcafedeadbeef, nibble 12:
+     OUT: 0f00dcafedea
+[8] L IN: f00dcafedeadbeef, nibble 12:
+     OUT: 00dcafedeadb
+[6] R IN: b00bbabeface, nibble 12:
+     OUT: 0b00bbabefac
+[6] L IN: b00bbabeface, nibble 12:
+     OUT: 00bbabeface0