Add faster decimal digit counting function

5 files changed, 112 insertions, 1 deletions

diff --git a/src/decimal.c b/src/decimal.c
new file mode 100644
index 00000000..7f78c8a7
--- /dev/null
+++ b/src/decimal.c
@@ -0,0 +1,25 @@
+/*
+  Copyright 2019 David Robillard <http://drobilla.net>
+
+  Permission to use, copy, modify, and/or distribute this software for any
+  purpose with or without fee is hereby granted, provided that the above
+  copyright notice and this permission notice appear in all copies.
+
+  THIS SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+
+#include "decimal.h"
+
+#include "int_math.h"
+
+int
+serd_count_digits(const uint64_t i)
+{
+	return i == 0 ? 1 : (int)serd_ilog10(i) + 1;
+}
diff --git a/src/decimal.h b/src/decimal.h
new file mode 100644
index 00000000..11e6a9bf
--- /dev/null
+++ b/src/decimal.h
@@ -0,0 +1,26 @@
+/*
+  Copyright 2019 David Robillard <http://drobilla.net>
+
+  Permission to use, copy, modify, and/or distribute this software for any
+  purpose with or without fee is hereby granted, provided that the above
+  copyright notice and this permission notice appear in all copies.
+
+  THIS SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+
+#ifndef SERD_DECIMAL_H
+#define SERD_DECIMAL_H
+
+#include <stdint.h>
+
+/// Return the number of decimal digits required to represent `n`
+int
+serd_count_digits(uint64_t i);
+
+#endif // SERD_DECIMAL_H
diff --git a/src/node.c b/src/node.c
index 633f4567..b362aaa8 100644
--- a/src/node.c
+++ b/src/node.c
@@ -16,6 +16,7 @@
 
 #include "node.h"
 
+#include "decimal.h"
 #include "namespaces.h"
 #include "static_nodes.h"
 #include "string_utils.h"
@@ -640,7 +641,7 @@ serd_new_integer(int64_t i, const SerdNode* datatype)
 {
 	const SerdNode* type      = datatype ? datatype : &serd_xsd_integer.node;
     uint64_t        abs_i     = (uint64_t)((i < 0) ? -i : i);
-    const unsigned  digits    = serd_digits((double)abs_i);
+	const unsigned  digits    = (unsigned)serd_count_digits(abs_i);
 	const size_t    type_len  = serd_node_total_size(type);
 	const size_t    total_len = digits + 2 + type_len;
 
diff --git a/tests/decimal_test.c b/tests/decimal_test.c
new file mode 100644
index 00000000..b0361e2c
--- /dev/null
+++ b/tests/decimal_test.c
@@ -0,0 +1,55 @@
+/*
+  Copyright 2011-2019 David Robillard <http://drobilla.net>
+
+  Permission to use, copy, modify, and/or distribute this software for any
+  purpose with or without fee is hereby granted, provided that the above
+  copyright notice and this permission notice appear in all copies.
+
+  THIS SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+  WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+  MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+  ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+  WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+  ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+  OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+
+#undef NDEBUG
+
+#include "../src/decimal.h"
+
+#include <assert.h>
+
+static void
+test_count_digits(void)
+{
+	assert(1 == serd_count_digits(0));
+	assert(1 == serd_count_digits(1));
+	assert(1 == serd_count_digits(9));
+	assert(2 == serd_count_digits(10));
+	assert(2 == serd_count_digits(99ull));
+	assert(3 == serd_count_digits(999ull));
+	assert(4 == serd_count_digits(9999ull));
+	assert(5 == serd_count_digits(99999ull));
+	assert(6 == serd_count_digits(999999ull));
+	assert(7 == serd_count_digits(9999999ull));
+	assert(8 == serd_count_digits(99999999ull));
+	assert(9 == serd_count_digits(999999999ull));
+	assert(10 == serd_count_digits(9999999999ull));
+	assert(11 == serd_count_digits(99999999999ull));
+	assert(12 == serd_count_digits(999999999999ull));
+	assert(13 == serd_count_digits(9999999999999ull));
+	assert(14 == serd_count_digits(99999999999999ull));
+	assert(15 == serd_count_digits(999999999999999ull));
+	assert(16 == serd_count_digits(9999999999999999ull));
+	assert(17 == serd_count_digits(99999999999999999ull));
+	assert(18 == serd_count_digits(999999999999999999ull));
+	assert(19 == serd_count_digits(9999999999999999999ull));
+	assert(20 == serd_count_digits(18446744073709551615ull));
+}
+
+int
+main(void)
+{
+	test_count_digits();
+}
diff --git a/wscript b/wscript
index 585789d6..b43626d0 100644
--- a/wscript
+++ b/wscript
@@ -73,6 +73,7 @@ def configure(conf):
             'msvc': [
                 '/wd4061',  # enumerator in switch is not explicitly handled
                 '/wd4200',  # nonstandard: zero-sized array in struct/union
+                '/wd4464',  # relative include path contains '..'
                 '/wd4514',  # unreferenced inline function has been removed
                 '/wd4710',  # function not inlined
                 '/wd4711',  # function selected for automatic inline expansion
@@ -168,6 +169,7 @@ lib_source = ['src/base64.c',
               'src/byte_sink.c',
               'src/byte_source.c',
               'src/cursor.c',
+              'src/decimal.c',
               'src/env.c',
               'src/inserter.c',
               'src/int_math.c',
@@ -255,6 +257,7 @@ def build(bld):
         for prog in [('serdi_static', 'src/serdi.c'),
                      ('base64_test', 'tests/base64_test.c'),
                      ('cursor_test', 'tests/cursor_test.c'),
+                     ('decimal_test', 'tests/decimal_test.c'),
                      ('env_test', 'tests/env_test.c'),
                      ('free_null_test', 'tests/free_null_test.c'),
                      ('int_math_test', 'tests/int_math_test.c'),
@@ -686,6 +689,7 @@ def test(tst):
     with tst.group('Unit') as check:
         check(['./base64_test'])
         check(['./cursor_test'])
+        check(['./decimal_test'])
         check(['./env_test'])
         check(['./free_null_test'])
         check(['./int_math_test'])