Use bit trick for portable and arm popcount

3 files changed, 44 insertions, 0 deletions

diff --git a/test/016_popcount_u32/00_all.in b/test/016_popcount_u32/00_all.in
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/test/016_popcount_u32/00_all.in
diff --git a/test/016_popcount_u32/00_all.out b/test/016_popcount_u32/00_all.out
new file mode 100644
index 0000000..7326d96
--- /dev/null
+++ b/test/016_popcount_u32/00_all.out
@@ -0,0 +1 @@
+Ok
diff --git a/test/016_popcount_u32/popcount_u32_tests.c b/test/016_popcount_u32/popcount_u32_tests.c
new file mode 100644
index 0000000..ff60c68
--- /dev/null
+++ b/test/016_popcount_u32/popcount_u32_tests.c
@@ -0,0 +1,43 @@
+#include "../test.h"
+
+int popcount_u32(uint32_t x);
+
+int
+popcount_u32_simple(uint32_t x)
+{
+        int ret;
+
+        for (ret = 0; x != 0; x >>= 1)
+                ret += x & 1;
+
+        return ret;
+}
+
+bool
+correct(uint32_t x)
+{
+        int expected = popcount_u32_simple(x);
+        int actual = popcount_u32(x);
+        if (actual != expected) {
+                printf("Error at %" PRIu32 ": expected %d bits, found %d\n",
+                    x, expected, actual);
+                return false;
+        }
+        return true;
+}
+
+void run(void) {
+        uint32_t i;
+
+        /* Test all numbers up to 2^16, and other ranges of 2^16 numbers */
+        for (i = 0; i < 0xFFFF; i++) {
+                if (!correct(i) ||
+                    !correct(i + UINT32_C(0xFFFF0000)) ||
+                    !correct(i + UINT32_C(1000000)) ||
+                    !correct(i + UINT32_C(1)) ||
+                    !correct(i + UINT32_C(1234567)))
+                    return;
+        }
+
+        printf("Ok\n");
+}