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bug#22689: [PATCH] Add logcount
From: |
Mark Oteiza |
Subject: |
bug#22689: [PATCH] Add logcount |
Date: |
Fri, 29 Sep 2017 13:41:34 -0400 |
User-agent: |
NeoMutt/20170912-48-0df7d3-dirty |
Hi,
I made an attempt implementing this:
diff --git a/src/data.c b/src/data.c
index e070be6c20..1332173dcd 100644
--- a/src/data.c
+++ b/src/data.c
@@ -3069,6 +3069,57 @@ usage: (logxor &rest INTS-OR-MARKERS) */)
return arith_driver (Alogxor, nargs, args);
}
+#if defined (__POPCNT__) && defined (__GNUC__) && (__GNUC__> 4 || (__GNUC__==
4 && __GNUC_MINOR__> 1))
+#define HAVE_BUILTIN_POPCOUNTLL
+#endif
+
+static uint32_t
+bitcount32 (uint32_t b)
+{
+ b -= (b >> 1) & 0x55555555;
+ b = (b & 0x33333333) + ((b >> 2) & 0x33333333);
+ b = (b + (b >> 4)) & 0x0f0f0f0f;
+ return (b * 0x01010101) >> 24;
+}
+
+static uint64_t
+bitcount64 (uint64_t b)
+{
+ b -= (b >> 1) & 0x5555555555555555;
+ b = (b & 0x3333333333333333) + ((b >> 2) & 0x3333333333333333);
+ b = (b + (b >> 4)) & 0x0f0f0f0f0f0f0f0f;
+ return (b * 0x0101010101010101) >> 56;
+}
+
+DEFUN ("logcount", Flogcount, Slogcount, 1, 1, 0,
+ doc: /* Return population count of VALUE. */)
+ (register Lisp_Object value)
+{
+ Lisp_Object res;
+
+ CHECK_NUMBER (value);
+
+#ifdef HAVE_BUILTIN_POPCOUNTLL
+ XSETINT (res, __builtin_popcount (XUINT (value)));
+#else /* HAVE_BUILTIN_POPCOUNTLL */
+ if (XINT (value) <= UINT_MAX)
+ XSETINT (res, bitcount32 (XUINT (value)));
+ else if (XINT (value) <= ULONG_MAX)
+ XSETINT (res, bitcount64 (XUINT (value)));
+ else
+ {
+ int count;
+ EMACS_UINT v = XUINT (value);
+ for (count = 0; v; count++)
+ {
+ v &= v - 1;
+ }
+ XSETINT (res, v);
+ }
+#endif /* HAVE_BUILTIN_POPCOUNTLL */
+ return res;
+}
+
static Lisp_Object
ash_lsh_impl (Lisp_Object value, Lisp_Object count, bool lsh)
{
@@ -3856,6 +3907,7 @@ syms_of_data (void)
defsubr (&Slogand);
defsubr (&Slogior);
defsubr (&Slogxor);
+ defsubr (&Slogcount);
defsubr (&Slsh);
defsubr (&Sash);
defsubr (&Sadd1);
- bug#22689: [PATCH] Add logcount,
Mark Oteiza <=
- bug#22689: [PATCH] Add logcount, Eli Zaretskii, 2017/09/30
- bug#22689: [PATCH] Add logcount, Mark Oteiza, 2017/09/30
- bug#22689: [PATCH] Add logcount, Eli Zaretskii, 2017/09/30
- bug#22689: [PATCH] Add logcount, Mark Oteiza, 2017/09/30
- bug#22689: [PATCH] Add logcount, Eli Zaretskii, 2017/09/30
- bug#22689: [PATCH] Add logcount, Mark Oteiza, 2017/09/30
- bug#22689: [PATCH] Add logcount, Eli Zaretskii, 2017/09/30
- bug#22689: [PATCH] Add logcount, Mark Oteiza, 2017/09/30
- bug#22689: [PATCH] Add logcount, Eli Zaretskii, 2017/09/30
- bug#22689: [PATCH] Add logcount, Mark Oteiza, 2017/09/30