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authorbfredl <bjorn.linse@gmail.com>2023-12-16 11:39:30 +0100
committerGitHub <noreply@github.com>2023-12-16 11:39:30 +0100
commit7e7da962de404e3a0952bcc0adc6fbe53eda3cfb (patch)
tree53bb22a303e70b589e6495b42ebae90c128ffe56 /src/nvim/math.c
parent7cae94e91e495c6ffbd32c8e9ba7d3c572610409 (diff)
parent3c2c022e5e299ecac4663c3813e2db5e2b099ffa (diff)
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Merge pull request #26512 from famiu/refactor/options/type_flags
refactor(options): remove option type macros
Diffstat (limited to 'src/nvim/math.c')
-rw-r--r--src/nvim/math.c26
1 files changed, 26 insertions, 0 deletions
diff --git a/src/nvim/math.c b/src/nvim/math.c
index 79e0be691b..9a0825823c 100644
--- a/src/nvim/math.c
+++ b/src/nvim/math.c
@@ -40,3 +40,29 @@ int xisnan(double d)
{
return FP_NAN == xfpclassify(d);
}
+
+/// Count trailing zeroes at the end of bit field.
+int xctz(uint64_t x)
+{
+ // If x == 0, that means all bits are zeroes.
+ if (x == 0) {
+ return 8 * sizeof(x);
+ }
+
+ // Use compiler builtin if possible.
+#if defined(__clang__) || (defined(__GNUC__) && (__GNUC__ >= 4))
+ return __builtin_ctzll(x);
+#else
+ int count = 0;
+ // Set x's trailing zeroes to ones and zero the rest.
+ x = (x ^ (x - 1)) >> 1;
+
+ // Increment count until there are just zero bits remaining.
+ while (x) {
+ count++;
+ x >>= 1;
+ }
+
+ return count;
+#endif
+}