printf("ccan/alignof\n");
printf("ccan/build_assert\n");
printf("ccan/compiler\n");
+ printf("ccan/ilog\n");
printf("ccan/likely\n");
printf("ccan/short_types\n");
return 0;
#include "bitops.h"
#include "config.h"
+#include <ccan/build_assert/build_assert.h>
#include <ccan/short_types/short_types.h>
+#include <ccan/ilog/ilog.h>
#include <limits.h>
unsigned int fls(unsigned long val)
{
-#if HAVE_BUILTIN_CLZL
- /* This is significantly faster! */
- return val ? sizeof(long) * CHAR_BIT - __builtin_clzl(val) : 0;
-#else
- unsigned int r = 32;
-
- if (!val)
- return 0;
- if (!(val & 0xffff0000u)) {
- val <<= 16;
- r -= 16;
- }
- if (!(val & 0xff000000u)) {
- val <<= 8;
- r -= 8;
- }
- if (!(val & 0xf0000000u)) {
- val <<= 4;
- r -= 4;
- }
- if (!(val & 0xc0000000u)) {
- val <<= 2;
- r -= 2;
- }
- if (!(val & 0x80000000u)) {
- val <<= 1;
- r -= 1;
- }
- return r;
-#endif
+ BUILD_ASSERT(sizeof(val) == sizeof(u32) || sizeof(val) == sizeof(u64));
+ if (sizeof(val) == sizeof(u32))
+ return ilog32(val);
+ else
+ return ilog64(val);
}
/* FIXME: Move to bitops. */
/**
* ilog - Integer logarithm.
*
- * ILOG_32() and ILOG_64() compute the minimum number of bits required to store
+ * ilog_32() and ilog_64() compute the minimum number of bits required to store
* an unsigned 32-bit or 64-bit value without any leading zero bits.
* This can also be thought of as the location of the highest set bit, with
* counting starting from one (so that 0 returns 0, 1 returns 1, and 2**31
* returns 32).
- * When the value is known to be non-zero ILOGNZ_32() and ILOGNZ_64() can
+ * When the value is known to be non-zero ilog32_nz() and ilog64_nz() can
* compile into as few as two instructions, one of which may get optimized out
* later.
* STATIC_ILOG_32 and STATIC_ILOG_64 allow computation on compile-time
*
* int main(void){
* int i;
- * printf("ILOG_32(0x%08X)=%i\n",0,ILOG_32(0));
+ * printf("ilog32(0x%08X)=%i\n",0,ilog32(0));
* for(i=1;i<=STATIC_ILOG_32(USHRT_MAX);i++){
* uint32_t v;
* v=(uint32_t)1U<<(i-1);
- * //Here we know v is non-zero, so we can use ILOGNZ_32().
- * printf("ILOG_32(0x%08X)=%i\n",v,ILOGNZ_32(v));
+ * //Here we know v is non-zero, so we can use ilog32_nz().
+ * printf("ilog32(0x%08X)=%i\n",v,ilog32_nz(v));
* }
* return 0;
* }
* License: LGPL (v2 or later)
*/
#include <string.h>
+#include <stdio.h>
#include "config.h"
int main(int _argc,const char *_argv[]){
/*Expect exactly one argument.*/
if(_argc!=2)return 1;
if(strcmp(_argv[1],"depends")==0){
- /*PRINTF-CCAN-PACKAGES-YOU-NEED-ONE-PER-LINE-IF-ANY*/
+ printf("ccan/compiler\n");
return 0;
}
return 1;
year=1998,
note="\url{http://supertech.csail.mit.edu/papers/debruijn.pdf}"
}*/
-#if !defined(ILOG_NODEBRUIJN)&& \
- !defined(CLZ32)||!defined(CLZ64)&&LONG_MAX<9223372036854775807LL
-static const unsigned char DEBRUIJN_IDX32[32]={
+static UNNEEDED_ATTRIBUTE const unsigned char DEBRUIJN_IDX32[32]={
0, 1,28, 2,29,14,24, 3,30,22,20,15,25,17, 4, 8,
31,27,13,23,21,19,16, 7,26,12,18, 6,11, 5,10, 9
};
-#endif
+
+/* We always compile these in, in case someone takes address of function. */
+#undef ilog32_nz
+#undef ilog32
+#undef ilog64_nz
+#undef ilog64
int ilog32(uint32_t _v){
-#if defined(CLZ32)
- return (CLZ32_OFFS-CLZ32(_v))&-!!_v;
-#else
/*On a Pentium M, this branchless version tested as the fastest version without
multiplications on 1,000,000,000 random 32-bit integers, edging out a
similar version with branches, and a 256-entry LUT version.*/
ret+=DEBRUIJN_IDX32[_v*0x77CB531U>>27&0x1F];
return ret;
# endif
-#endif
+}
+
+int ilog32_nz(uint32_t _v)
+{
+ return ilog32(_v);
}
int ilog64(uint64_t _v){
-#if defined(CLZ64)
- return (CLZ64_OFFS-CLZ64(_v))&-!!_v;
-#else
# if defined(ILOG_NODEBRUIJN)
uint32_t v;
int ret;
return ret;
# endif
# endif
-#endif
}
+
+int ilog64_nz(uint64_t _v)
+{
+ return ilog64(_v);
+}
+
# define _ilog_H (1)
# include "config.h"
# include <stdint.h>
-# include <ccan/compiler/compiler.h>
# include <limits.h>
-/*Note the casts to (int) below: this prevents CLZ{32|64}_OFFS from "upgrading"
- the type of an entire expression to an (unsigned) size_t.*/
-# if HAVE_BUILTIN_CLZ && INT_MAX>=2147483647
-# define CLZ32_OFFS ((int)sizeof(unsigned)*CHAR_BIT)
-# define CLZ32(_x) (__builtin_clz(_x))
-# elif HAVE_BUILTIN_CLZL && LONG_MAX>=2147483647L
-# define CLZ32_OFFS ((int)sizeof(unsigned long)*CHAR_BIT)
-# define CLZ32(_x) (__builtin_clzl(_x))
-# endif
-
-# if HAVE_BUILTIN_CLZ && INT_MAX>=9223372036854775807LL
-# define CLZ64_OFFS ((int)sizeof(unsigned)*CHAR_BIT)
-# define CLZ64(_x) (__builtin_clz(_x))
-# elif HAVE_BUILTIN_CLZL && LONG_MAX>=9223372036854775807LL
-# define CLZ64_OFFS ((int)sizeof(unsigned long)*CHAR_BIT)
-# define CLZ64(_x) (__builtin_clzl(_x))
-# elif HAVE_BUILTIN_CLZLL /* long long must be >= 64 bits according to ISO C */
-# define CLZ64_OFFS ((int)sizeof(unsigned long long)*CHAR_BIT)
-# define CLZ64(_x) (__builtin_clzll(_x))
-# endif
-
-
+# include <ccan/compiler/compiler.h>
/**
* ilog32 - Integer binary logarithm of a 32-bit value.
* Returns floor(log2(_v))+1, or 0 if _v==0.
* This is the number of bits that would be required to represent _v in two's
* complement notation with all of the leading zeros stripped.
- * The ILOG_32() or ILOGNZ_32() macros may be able to use a builtin function
- * instead, which should be faster.
+ * Note that many uses will resolve to the fast macro version instead.
+ *
+ * See Also:
+ * ilog32_nz(), ilog64()
+ *
+ * Example:
+ * // Rounds up to next power of 2 (if not a power of 2).
+ * static uint32_t round_up32(uint32_t i)
+ * {
+ * assert(i != 0);
+ * return 1U << ilog32(i-1);
+ * }
*/
int ilog32(uint32_t _v) IDEMPOTENT_ATTRIBUTE;
+
+/**
+ * ilog32_nz - Integer binary logarithm of a non-zero 32-bit value.
+ * @_v: A 32-bit value.
+ * Returns floor(log2(_v))+1, or undefined if _v==0.
+ * This is the number of bits that would be required to represent _v in two's
+ * complement notation with all of the leading zeros stripped.
+ * Note that many uses will resolve to the fast macro version instead.
+ * See Also:
+ * ilog32(), ilog64_nz()
+ * Example:
+ * // Find Last Set (ie. highest bit set, 0 to 31).
+ * static uint32_t fls32(uint32_t i)
+ * {
+ * assert(i != 0);
+ * return ilog32_nz(i) - 1;
+ * }
+ */
+int ilog32_nz(uint32_t _v) IDEMPOTENT_ATTRIBUTE;
+
/**
* ilog64 - Integer binary logarithm of a 64-bit value.
* @_v: A 64-bit value.
* Returns floor(log2(_v))+1, or 0 if _v==0.
* This is the number of bits that would be required to represent _v in two's
* complement notation with all of the leading zeros stripped.
- * The ILOG_64() or ILOGNZ_64() macros may be able to use a builtin function
- * instead, which should be faster.
+ * Note that many uses will resolve to the fast macro version instead.
+ * See Also:
+ * ilog64_nz(), ilog32()
*/
int ilog64(uint64_t _v) IDEMPOTENT_ATTRIBUTE;
-
-# if defined(CLZ32)
/**
- * ILOGNZ_32 - Integer binary logarithm of a non-zero 32-bit value.
- * @_v: A non-zero 32-bit value.
- * Returns floor(log2(_v))+1.
+ * ilog64_nz - Integer binary logarithm of a non-zero 64-bit value.
+ * @_v: A 64-bit value.
+ * Returns floor(log2(_v))+1, or undefined if _v==0.
* This is the number of bits that would be required to represent _v in two's
* complement notation with all of the leading zeros stripped.
- * If _v is zero, the return value is undefined; use ILOG_32() instead.
+ * Note that many uses will resolve to the fast macro version instead.
+ * See Also:
+ * ilog64(), ilog32_nz()
*/
-# define ILOGNZ_32(_v) (CLZ32_OFFS-CLZ32(_v))
+int ilog64_nz(uint64_t _v) IDEMPOTENT_ATTRIBUTE;
+
/**
- * ILOG_32 - Integer binary logarithm of a 32-bit value.
- * @_v: A 32-bit value.
+ * STATIC_ILOG_32 - The integer logarithm of an (unsigned, 32-bit) constant.
+ * @_v: A non-negative 32-bit constant.
* Returns floor(log2(_v))+1, or 0 if _v==0.
* This is the number of bits that would be required to represent _v in two's
* complement notation with all of the leading zeros stripped.
+ * This macro should only be used when you need a compile-time constant,
+ * otherwise ilog32 or ilog32_nz are just as fast and more flexible.
+ *
+ * Example:
+ * #define MY_PAGE_SIZE 4096
+ * #define MY_PAGE_BITS (STATIC_ILOG_32(PAGE_SIZE) - 1)
*/
-# define ILOG_32(_v) (ILOGNZ_32(_v)&-!!(_v))
-# else
-# define ILOGNZ_32(_v) (ilog32(_v))
-# define ILOG_32(_v) (ilog32(_v))
-# endif
+#define STATIC_ILOG_32(_v) (STATIC_ILOG5((uint32_t)(_v)))
-# if defined(CLZ64)
/**
- * ILOGNZ_64 - Integer binary logarithm of a non-zero 64-bit value.
- * @_v: A non-zero 64-bit value.
- * Returns floor(log2(_v))+1.
- * This is the number of bits that would be required to represent _v in two's
- * complement notation with all of the leading zeros stripped.
- * If _v is zero, the return value is undefined; use ILOG_64() instead.
- */
-# define ILOGNZ_64(_v) (CLZ64_OFFS-CLZ64(_v))
-/**
- * ILOG_64 - Integer binary logarithm of a 64-bit value.
- * @_v: A 64-bit value.
+ * STATIC_ILOG_64 - The integer logarithm of an (unsigned, 64-bit) constant.
+ * @_v: A non-negative 64-bit constant.
* Returns floor(log2(_v))+1, or 0 if _v==0.
* This is the number of bits that would be required to represent _v in two's
* complement notation with all of the leading zeros stripped.
+ * This macro should only be used when you need a compile-time constant,
+ * otherwise ilog64 or ilog64_nz are just as fast and more flexible.
*/
-# define ILOG_64(_v) (ILOGNZ_64(_v)&-!!(_v))
-# else
-# define ILOGNZ_64(_v) (ilog64(_v))
-# define ILOG_64(_v) (ilog64(_v))
-# endif
+#define STATIC_ILOG_64(_v) (STATIC_ILOG6((uint64_t)(_v)))
+
+/* Private implementation details */
+
+/*Note the casts to (int) below: this prevents "upgrading"
+ the type of an entire expression to an (unsigned) size_t.*/
+#if INT_MAX>=2147483647 && HAVE_BUILTIN_CLZ
+#define builtin_ilog32_nz(v) \
+ (((int)sizeof(unsigned)*CHAR_BIT) - __builtin_clz(v))
+#elif LONG_MAX>=2147483647L && HAVE_BUILTIN_CLZL
+#define builtin_ilog32_nz(v) \
+ (((int)sizeof(unsigned)*CHAR_BIT) - __builtin_clzl(v))
+#endif
+
+#if INT_MAX>=9223372036854775807LL && HAVE_BUILTIN_CLZ
+#define builtin_ilog64_nz(v) \
+ (((int)sizeof(unsigned)*CHAR_BIT) - __builtin_clz(v))
+#elif LONG_MAX>=9223372036854775807LL && HAVE_BUILTIN_CLZL
+#define builtin_ilog64_nz(v) \
+ (((int)sizeof(unsigned long)*CHAR_BIT) - __builtin_clzl(v))
+#elif HAVE_BUILTIN_CLZLL
+#define builtin_ilog64_nz(v) \
+ (((int)sizeof(unsigned long long)*CHAR_BIT) - __builtin_clzll(v))
+#endif
+
+#ifdef builtin_ilog32_nz
+#define ilog32(_v) (builtin_ilog32_nz(_v)&-!!(_v))
+#define ilog32_nz(_v) builtin_ilog32_nz(_v)
+#else
+#define ilog32_nz(_v) ilog32(_v)
+#define ilog32(_v) (IS_COMPILE_CONSTANT(_v) ? STATIC_ILOG_32(_v) : ilog32(_v))
+#endif /* builtin_ilog32_nz */
+
+#ifdef builtin_ilog64_nz
+#define ilog64(_v) (builtin_ilog64_nz(_v)&-!!(_v))
+#define ilog64_nz(_v) builtin_ilog64_nz(_v)
+#else
+#define ilog64_nz(_v) ilog64(_v)
+#define ilog64(_v) (IS_COMPILE_CONSTANT(_v) ? STATIC_ILOG_64(_v) : ilog64(_v))
+#endif /* builtin_ilog64_nz */
+/* Macros for evaluating compile-time constant ilog. */
# define STATIC_ILOG0(_v) (!!(_v))
# define STATIC_ILOG1(_v) (((_v)&0x2)?2:STATIC_ILOG0(_v))
# define STATIC_ILOG2(_v) (((_v)&0xC)?2+STATIC_ILOG1((_v)>>2):STATIC_ILOG1(_v))
(((_v)&0xFFFF0000)?16+STATIC_ILOG4((_v)>>16):STATIC_ILOG4(_v))
# define STATIC_ILOG6(_v) \
(((_v)&0xFFFFFFFF00000000ULL)?32+STATIC_ILOG5((_v)>>32):STATIC_ILOG5(_v))
-/**
- * STATIC_ILOG_32 - The integer logarithm of an (unsigned, 32-bit) constant.
- * @_v: A non-negative 32-bit constant.
- * Returns floor(log2(_v))+1, or 0 if _v==0.
- * This is the number of bits that would be required to represent _v in two's
- * complement notation with all of the leading zeros stripped.
- * This macro is suitable for evaluation at compile time, but it should not be
- * used on values that can change at runtime, as it operates via exhaustive
- * search.
- */
-# define STATIC_ILOG_32(_v) (STATIC_ILOG5((uint32_t)(_v)))
-/**
- * STATIC_ILOG_64 - The integer logarithm of an (unsigned, 64-bit) constant.
- * @_v: A non-negative 64-bit constant.
- * Returns floor(log2(_v))+1, or 0 if _v==0.
- * This is the number of bits that would be required to represent _v in two's
- * complement notation with all of the leading zeros stripped.
- * This macro is suitable for evaluation at compile time, but it should not be
- * used on values that can change at runtime, as it operates via exhaustive
- * search.
- */
-# define STATIC_ILOG_64(_v) (STATIC_ILOG6((uint64_t)(_v)))
-#endif
+#endif /* _ilog_H */
--- /dev/null
+#include <ccan/ilog/ilog.h>
+#include <ccan/ilog/ilog.c>
+#include <stdio.h>
+#include <ccan/tap/tap.h>
+
+/*Dead simple (but slow) versions to compare against.*/
+
+static int test_ilog32(uint32_t _v){
+ int ret;
+ for(ret=0;_v;ret++)_v>>=1;
+ return ret;
+}
+
+static int test_ilog64(uint64_t _v){
+ int ret;
+ for(ret=0;_v;ret++)_v>>=1;
+ return ret;
+}
+
+#define NTRIALS (64)
+
+int main(int _argc,const char *_argv[]){
+ int i;
+ int j;
+ int (*il32)(uint32_t) = ilog32;
+ int (*il64)(uint64_t) = ilog64;
+ int (*il32_nz)(uint32_t) = ilog32_nz;
+ int (*il64_nz)(uint64_t) = ilog64_nz;
+
+ /*This is how many tests you plan to run.*/
+ plan_tests(33 * NTRIALS * 3 + 65 * NTRIALS * 3);
+ for(i=0;i<=32;i++){
+ uint32_t v;
+ /*Test each bit in turn (and 0).*/
+ v=i?(uint32_t)1U<<(i-1):0;
+ for(j=0;j<NTRIALS;j++){
+ int l;
+ l=test_ilog32(v);
+ ok1(STATIC_ILOG_32(v)==l);
+ ok1(il32(v)==l);
+ ok1(il32_nz(v) == l || v == 0);
+ /*Also try a few more pseudo-random values with at most the same number
+ of bits.*/
+ v=(1103515245U*v+12345U)&0xFFFFFFFFU>>((33-i)>>1)>>((32-i)>>1);
+ }
+ }
+
+ for(i=0;i<=64;i++){
+ uint64_t v;
+ /*Test each bit in turn (and 0).*/
+ v=i?(uint64_t)1U<<(i-1):0;
+ for(j=0;j<NTRIALS;j++){
+ int l;
+ l=test_ilog64(v);
+ ok1(STATIC_ILOG_64(v)==l);
+ ok1(il64(v)==l);
+ ok1(il64_nz(v) == l || v == 0);
+ /*Also try a few more pseudo-random values with at most the same number
+ of bits.*/
+ v=(uint64_t)((2862933555777941757ULL*v+3037000493ULL)
+ &0xFFFFFFFFFFFFFFFFULL>>((65-i)>>1)>>((64-i)>>1));
+ }
+ }
+ return exit_status();
+}
#define NTRIALS (64)
int main(int _argc,const char *_argv[]){
- int nmatches;
int i;
int j;
/*This is how many tests you plan to run.*/
- plan_tests(2);
- nmatches=0;
+ plan_tests(33 * NTRIALS * 3 + 65 * NTRIALS * 3);
for(i=0;i<=32;i++){
uint32_t v;
/*Test each bit in turn (and 0).*/
for(j=0;j<NTRIALS;j++){
int l;
l=test_ilog32(v);
- if(ILOG_32(v)!=l){
- fprintf(stderr,"ILOG_32(0x%08lX): %i != %i\n",(long)v,ILOG_32(v),l);
- }
- else nmatches++;
- if(ilog32(v)!=l){
- fprintf(stderr,"ilog32(0x%08lX): %i != %i\n",(long)v,ilog32(v),l);
- }
- else nmatches++;
- if(STATIC_ILOG_32(v)!=l){
- fprintf(stderr,"STATIC_ILOG_32(0x%08lX): %i != %i\n",
- (long)v,STATIC_ILOG_32(v),l);
- }
- else nmatches++;
+ ok1(STATIC_ILOG_32(v)==l);
+ ok1(ilog32(v)==l);
+ ok1(ilog32_nz(v) == l || v == 0);
/*Also try a few more pseudo-random values with at most the same number
of bits.*/
v=(1103515245U*v+12345U)&0xFFFFFFFFU>>((33-i)>>1)>>((32-i)>>1);
}
}
- ok1(nmatches==3*(32+1)*NTRIALS);
- nmatches=0;
+
for(i=0;i<=64;i++){
uint64_t v;
/*Test each bit in turn (and 0).*/
for(j=0;j<NTRIALS;j++){
int l;
l=test_ilog64(v);
- if(ILOG_64(v)!=l){
- fprintf(stderr,"ILOG_64(0x%016llX): %i != %i\n",
- (long long)v,ILOG_64(v),l);
- }
- else nmatches++;
- if(ilog64(v)!=l){
- fprintf(stderr,"ilog64(0x%016llX): %i != %i\n",
- (long long)v,ilog64(v),l);
- }
- else nmatches++;
- if(STATIC_ILOG_64(v)!=l){
- fprintf(stderr,"STATIC_ILOG_64(0x%016llX): %i != %i\n",
- (long long)v,STATIC_ILOG_64(v),l);
- }
- else nmatches++;
+ ok1(STATIC_ILOG_64(v)==l);
+ ok1(ilog64(v)==l);
+ ok1(ilog64_nz(v) == l || v == 0);
/*Also try a few more pseudo-random values with at most the same number
of bits.*/
v=(uint64_t)((2862933555777941757ULL*v+3037000493ULL)
&0xFFFFFFFFFFFFFFFFULL>>((65-i)>>1)>>((64-i)>>1));
}
}
- ok1(nmatches==3*(64+1)*NTRIALS);
return exit_status();
}
FLT_MANT_DIG+1 consecutive one bits.
Even the fallback C implementation of ILOGNZ_32() yields an implementation
25% faster than the frexp() method.*/
- nbits_needed=FLT_MANT_DIG-ILOGNZ_32(_bits);
+ nbits_needed=FLT_MANT_DIG-ilog32_nz(_bits);
#if FLT_MANT_DIG>32
ret=ldexpf((float)_bits,_base);
# if FLT_MANT_DIG>65
_base-=32;
_bits=isaac_next_uint32(_ctx);
}
- nbits_needed=DBL_MANT_DIG-ILOGNZ_32(_bits);
+ nbits_needed=DBL_MANT_DIG-ilog32_nz(_bits);
#if DBL_MANT_DIG>32
ret=ldexp((double)_bits,_base);
# if DBL_MANT_DIG>65
_base-=64;
_bits=isaac64_next_uint64(_ctx);
}
- nbits_needed=FLT_MANT_DIG-ILOGNZ_64(_bits);
+ nbits_needed=FLT_MANT_DIG-ilog64_nz(_bits);
#if FLT_MANT_DIG>64
ret=ldexpf((float)_bits,_base);
# if FLT_MANT_DIG>129
_base-=64;
_bits=isaac64_next_uint64(_ctx);
}
- nbits_needed=DBL_MANT_DIG-ILOGNZ_64(_bits);
+ nbits_needed=DBL_MANT_DIG-ilog64_nz(_bits);
#if DBL_MANT_DIG>64
ret=ldexp((double)_bits,_base);
# if DBL_MANT_DIG>129
printf("ccan/asearch\n");
printf("ccan/compiler\n");
printf("ccan/build_assert\n");
+ printf("ccan/ilog\n");
printf("ccan/tally\n");
return 0;
}
*/
#include "private.h"
#include <ccan/likely/likely.h>
+#include <ccan/ilog/ilog.h>
#include <time.h>
#include <assert.h>
#include <limits.h>
static unsigned fls64(uint64_t val)
{
-#if HAVE_BUILTIN_CLZL
- if (val <= ULONG_MAX) {
- /* This is significantly faster! */
- return val ? sizeof(long) * CHAR_BIT - __builtin_clzl(val) : 0;
- } else {
-#endif
- uint64_t r = 64;
-
- if (!val)
- return 0;
- if (!(val & 0xffffffff00000000ull)) {
- val <<= 32;
- r -= 32;
- }
- if (!(val & 0xffff000000000000ull)) {
- val <<= 16;
- r -= 16;
- }
- if (!(val & 0xff00000000000000ull)) {
- val <<= 8;
- r -= 8;
- }
- if (!(val & 0xf000000000000000ull)) {
- val <<= 4;
- r -= 4;
- }
- if (!(val & 0xc000000000000000ull)) {
- val <<= 2;
- r -= 2;
- }
- if (!(val & 0x8000000000000000ull)) {
- val <<= 1;
- r -= 1;
- }
- return r;
-#if HAVE_BUILTIN_CLZL
- }
-#endif
+ return ilog64(val);
}
/* In which bucket would we find a particular record size? (ignoring header) */
projects / ccan / commitdiff