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host-utils: Fix coding style and add comments

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Add function comments to the routines, documenting the corner
cases upon which we are standardizing.  Fix the few instances
of non-standard coding style.

Signed-off-by: Richard Henderson <rth@twiddle.net>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
This commit is contained in:
Richard Henderson 2013-02-13 17:47:35 -08:00 committed by Blue Swirl
parent 0165437302
commit 72d81155d0
1 changed files with 82 additions and 18 deletions
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100
include/qemu/host-utils.h
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@ -50,16 +50,19 @@ void muls64(uint64_t *phigh, uint64_t *plow, int64_t a, int64_t b);
void mulu64(uint64_t *phigh, uint64_t *plow, uint64_t a, uint64_t b);
#endif
/* Binary search for leading zeros. */
/**
* clz32 - count leading zeros in a 32-bit value.
* @val: The value to search
*
* Returns 32 if the value is zero. Note that the GCC builtin is
* undefined if the value is zero.
*/
static inline int clz32(uint32_t val)
{
#if QEMU_GNUC_PREREQ(3, 4)
if (val)
return __builtin_clz(val);
else
return 32;
return val ? __builtin_clz(val) : 32;
#else
/* Binary search for the leading one bit. */
int cnt = 0;
if (!(val & 0xFFFF0000U)) {
@ -89,18 +92,28 @@ static inline int clz32(uint32_t val)
#endif
}
/**
* clo32 - count leading ones in a 32-bit value.
* @val: The value to search
*
* Returns 32 if the value is -1.
*/
static inline int clo32(uint32_t val)
{
return clz32(~val);
}
/**
* clz64 - count leading zeros in a 64-bit value.
* @val: The value to search
*
* Returns 64 if the value is zero. Note that the GCC builtin is
* undefined if the value is zero.
*/
static inline int clz64(uint64_t val)
{
#if QEMU_GNUC_PREREQ(3, 4)
if (val)
return __builtin_clzll(val);
else
return 64;
return val ? __builtin_clzll(val) : 64;
#else
int cnt = 0;
@ -114,19 +127,30 @@ static inline int clz64(uint64_t val)
#endif
}
/**
* clo64 - count leading ones in a 64-bit value.
* @val: The value to search
*
* Returns 64 if the value is -1.
*/
static inline int clo64(uint64_t val)
{
return clz64(~val);
}
/**
* ctz32 - count trailing zeros in a 32-bit value.
* @val: The value to search
*
* Returns 32 if the value is zero. Note that the GCC builtin is
* undefined if the value is zero.
*/
static inline int ctz32(uint32_t val)
{
#if QEMU_GNUC_PREREQ(3, 4)
if (val)
return __builtin_ctz(val);
else
return 32;
return val ? __builtin_ctz(val) : 32;
#else
/* Binary search for the trailing one bit. */
int cnt;
cnt = 0;
@ -158,18 +182,28 @@ static inline int ctz32(uint32_t val)
#endif
}
/**
* cto32 - count trailing ones in a 32-bit value.
* @val: The value to search
*
* Returns 32 if the value is -1.
*/
static inline int cto32(uint32_t val)
{
return ctz32(~val);
}
/**
* ctz64 - count trailing zeros in a 64-bit value.
* @val: The value to search
*
* Returns 64 if the value is zero. Note that the GCC builtin is
* undefined if the value is zero.
*/
static inline int ctz64(uint64_t val)
{
#if QEMU_GNUC_PREREQ(3, 4)
if (val)
return __builtin_ctzll(val);
else
return 64;
return val ? __builtin_ctzll(val) : 64;
#else
int cnt;
@ -183,30 +217,56 @@ static inline int ctz64(uint64_t val)
#endif
}
/**
* ctz64 - count trailing ones in a 64-bit value.
* @val: The value to search
*
* Returns 64 if the value is -1.
*/
static inline int cto64(uint64_t val)
{
return ctz64(~val);
}
/**
* ctpop8 - count the population of one bits in an 8-bit value.
* @val: The value to search
*/
static inline int ctpop8(uint8_t val)
{
#if QEMU_GNUC_PREREQ(3, 4)
return __builtin_popcount(val);
#else
val = (val & 0x55) + ((val >> 1) & 0x55);
val = (val & 0x33) + ((val >> 2) & 0x33);
val = (val & 0x0f) + ((val >> 4) & 0x0f);
return val;
#endif
}
/**
* ctpop16 - count the population of one bits in a 16-bit value.
* @val: The value to search
*/
static inline int ctpop16(uint16_t val)
{
#if QEMU_GNUC_PREREQ(3, 4)
return __builtin_popcount(val);
#else
val = (val & 0x5555) + ((val >> 1) & 0x5555);
val = (val & 0x3333) + ((val >> 2) & 0x3333);
val = (val & 0x0f0f) + ((val >> 4) & 0x0f0f);
val = (val & 0x00ff) + ((val >> 8) & 0x00ff);
return val;
#endif
}
/**
* ctpop32 - count the population of one bits in a 32-bit value.
* @val: The value to search
*/
static inline int ctpop32(uint32_t val)
{
#if QEMU_GNUC_PREREQ(3, 4)
@ -222,6 +282,10 @@ static inline int ctpop32(uint32_t val)
#endif
}
/**
* ctpop64 - count the population of one bits in a 64-bit value.
* @val: The value to search
*/
static inline int ctpop64(uint64_t val)
{
#if QEMU_GNUC_PREREQ(3, 4)