This is the mail archive of the
newlib@sourceware.org
mailing list for the newlib project.
Re: [PATCH v2] For RTEMS-LIBBSD support, add bitcount routines
- From: Sebastian Huber <sebastian dot huber at embedded-brains dot de>
- To: Kevin Kirspel <kevin-kirspel at idexx dot com>, newlib at sourceware dot org
- Date: Fri, 19 May 2017 07:50:29 +0200
- Subject: Re: [PATCH v2] For RTEMS-LIBBSD support, add bitcount routines
- Authentication-results: sourceware.org; auth=none
- References: <201705171306.v4HD3IpM000428@mx0a-00116901.pphosted.com>
On 17/05/17 15:06, Kevin Kirspel wrote:
---
newlib/libc/sys/rtems/include/machine/types.h | 58 +++++++++++++++++++++++++++
1 file changed, 58 insertions(+)
diff --git a/newlib/libc/sys/rtems/include/machine/types.h b/newlib/libc/sys/rtems/include/machine/types.h
index b28f923..0b0a100 100644
--- a/newlib/libc/sys/rtems/include/machine/types.h
+++ b/newlib/libc/sys/rtems/include/machine/types.h
@@ -83,3 +83,61 @@ typedef __uintmax_t rman_res_t;
#endif
#endif /* __BSD_VISIBLE */
+
+#ifdef __POPCNT__
+#define __bitcount64(x) __builtin_popcountll((__uint64_t)(x))
+#define __bitcount32(x) __builtin_popcount((__uint32_t)(x))
+#define __bitcount16(x) __builtin_popcount((__uint16_t)(x))
+#define __bitcountl(x) __builtin_popcountl((unsigned long)(x))
+#define __bitcount(x) __builtin_popcount((unsigned int)(x))
+#else /* __POPCNT__ */
+/*
+ * Population count algorithm using SWAR approach
+ * - "SIMD Within A Register".
+ */
+static __inline __uint16_t
+__bitcount16(__uint16_t _x)
+{
+ _x = (_x & 0x5555) + ((_x & 0xaaaa) >> 1);
+ _x = (_x & 0x3333) + ((_x & 0xcccc) >> 2);
+ _x = (_x + (_x >> 4)) & 0x0f0f;
+ _x = (_x + (_x >> 8)) & 0x00ff;
+ return (_x);
+}
+
+static __inline __uint32_t
+__bitcount32(__uint32_t _x)
+{
+ _x = (_x & 0x55555555) + ((_x & 0xaaaaaaaa) >> 1);
+ _x = (_x & 0x33333333) + ((_x & 0xcccccccc) >> 2);
+ _x = (_x + (_x >> 4)) & 0x0f0f0f0f;
+ _x = (_x + (_x >> 8));
+ _x = (_x + (_x >> 16)) & 0x000000ff;
+ return (_x);
+}
+
+#if __SIZEOF_INT__ == 8
+static __inline __uint64_t
+__bitcount64(__uint64_t _x)
+{
+ _x = (_x & 0x5555555555555555) + ((_x & 0xaaaaaaaaaaaaaaaa) >> 1);
+ _x = (_x & 0x3333333333333333) + ((_x & 0xcccccccccccccccc) >> 2);
+ _x = (_x + (_x >> 4)) & 0x0f0f0f0f0f0f0f0f;
+ _x = (_x + (_x >> 8));
+ _x = (_x + (_x >> 16));
+ _x = (_x + (_x >> 32)) & 0x000000ff;
+ return (_x);
+}
+
+#define __bitcountl(x) __bitcount64((unsigned long)(x))
+#else /* __SIZEOF_INT__ == 8 */
+static __inline __uint64_t
+__bitcount64(__uint64_t _x)
+{
+ return (__bitcount32(_x >> 32) + __bitcount32(_x));
+}
The __bitcount64() implementation should be based on the word size of
the architecture. Usually this is indicated by sizeof long.
+
+#define __bitcountl(x) __bitcount32((unsigned long)(x))
+#endif /* __SIZEOF_INT__ == 8 */
+#define __bitcount(x) __bitcount32((unsigned int)(x))
+#endif /* __POPCNT__ */
Selection of __bitcountl() should be based on sizeof long. Selection of
__bitcount() should be based on sizeof int. Maybe it makes sense to add
a test for this to the RTEMS testsuite and do a check of the
pre-processor output on the arm-rtems4.12, sparc64-rtems4.12 and
m32c-rtems4.12 targets.
--
Sebastian Huber, embedded brains GmbH
Address : Dornierstr. 4, D-82178 Puchheim, Germany
Phone : +49 89 189 47 41-16
Fax : +49 89 189 47 41-09
E-Mail : sebastian.huber@embedded-brains.de
PGP : Public key available on request.
Diese Nachricht ist keine geschäftliche Mitteilung im Sinne des EHUG.