py/misc: Move mp_clz and mp_ctz intrinsics into misc.h.

Signed-off-by: Angus Gratton <angus@redyak.com.au>

1 files changed, 18 insertions, 0 deletions

diff --git a/py/misc.h b/py/misc.h
index eea3e8b0f..9f8a8c1e1 100644
--- a/py/misc.h
+++ b/py/misc.h
@@ -334,4 +334,22 @@ typedef const char *mp_rom_error_text_t;
 // For now, forward directly to MP_COMPRESSED_ROM_TEXT.
 #define MP_ERROR_TEXT(x) (mp_rom_error_text_t)MP_COMPRESSED_ROM_TEXT(x)
 
+// Portable implementations of CLZ and CTZ intrinsics
+#ifdef _MSC_VER
+#include <intrin.h>
+
+static uint32_t mp_clz(uint32_t x) {
+    unsigned long lz = 0;
+    return _BitScanReverse(&lz, x) ? (sizeof(x) * 8 - 1) - lz : 0;
+}
+
+static uint32_t mp_ctz(uint32_t x) {
+    unsigned long tz = 0;
+    return _BitScanForward(&tz, x) ? tz : 0;
+}
+#else
+#define mp_clz(x) __builtin_clz(x)
+#define mp_ctz(x) __builtin_ctz(x)
+#endif
+
 #endif // MICROPY_INCLUDED_PY_MISC_H