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host-utils: Fix coding style and add comments
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>
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@ -50,16 +50,19 @@ void muls64(uint64_t *phigh, uint64_t *plow, int64_t a, int64_t b);
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void mulu64(uint64_t *phigh, uint64_t *plow, uint64_t a, uint64_t b);
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#endif
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/* Binary search for leading zeros. */
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/**
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* clz32 - count leading zeros in a 32-bit value.
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* @val: The value to search
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*
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* Returns 32 if the value is zero. Note that the GCC builtin is
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* undefined if the value is zero.
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*/
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static inline int clz32(uint32_t val)
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{
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#if QEMU_GNUC_PREREQ(3, 4)
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if (val)
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return __builtin_clz(val);
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else
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return 32;
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return val ? __builtin_clz(val) : 32;
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#else
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/* Binary search for the leading one bit. */
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int cnt = 0;
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if (!(val & 0xFFFF0000U)) {
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@ -89,18 +92,28 @@ static inline int clz32(uint32_t val)
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#endif
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}
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/**
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* clo32 - count leading ones in a 32-bit value.
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* @val: The value to search
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*
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* Returns 32 if the value is -1.
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*/
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static inline int clo32(uint32_t val)
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{
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return clz32(~val);
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}
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/**
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* clz64 - count leading zeros in a 64-bit value.
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* @val: The value to search
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*
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* Returns 64 if the value is zero. Note that the GCC builtin is
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* undefined if the value is zero.
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*/
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static inline int clz64(uint64_t val)
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{
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#if QEMU_GNUC_PREREQ(3, 4)
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if (val)
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return __builtin_clzll(val);
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else
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return 64;
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return val ? __builtin_clzll(val) : 64;
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#else
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int cnt = 0;
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@ -114,19 +127,30 @@ static inline int clz64(uint64_t val)
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#endif
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}
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/**
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* clo64 - count leading ones in a 64-bit value.
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* @val: The value to search
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*
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* Returns 64 if the value is -1.
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*/
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static inline int clo64(uint64_t val)
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{
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return clz64(~val);
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}
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/**
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* ctz32 - count trailing zeros in a 32-bit value.
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* @val: The value to search
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*
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* Returns 32 if the value is zero. Note that the GCC builtin is
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* undefined if the value is zero.
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*/
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static inline int ctz32(uint32_t val)
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{
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#if QEMU_GNUC_PREREQ(3, 4)
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if (val)
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return __builtin_ctz(val);
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else
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return 32;
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return val ? __builtin_ctz(val) : 32;
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#else
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/* Binary search for the trailing one bit. */
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int cnt;
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cnt = 0;
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@ -158,18 +182,28 @@ static inline int ctz32(uint32_t val)
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#endif
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}
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/**
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* cto32 - count trailing ones in a 32-bit value.
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* @val: The value to search
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*
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* Returns 32 if the value is -1.
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*/
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static inline int cto32(uint32_t val)
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{
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return ctz32(~val);
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}
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/**
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* ctz64 - count trailing zeros in a 64-bit value.
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* @val: The value to search
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*
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* Returns 64 if the value is zero. Note that the GCC builtin is
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* undefined if the value is zero.
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*/
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static inline int ctz64(uint64_t val)
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{
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#if QEMU_GNUC_PREREQ(3, 4)
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if (val)
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return __builtin_ctzll(val);
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else
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return 64;
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return val ? __builtin_ctzll(val) : 64;
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#else
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int cnt;
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@ -183,30 +217,56 @@ static inline int ctz64(uint64_t val)
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#endif
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}
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/**
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* ctz64 - count trailing ones in a 64-bit value.
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* @val: The value to search
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*
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* Returns 64 if the value is -1.
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*/
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static inline int cto64(uint64_t val)
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{
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return ctz64(~val);
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}
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/**
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* ctpop8 - count the population of one bits in an 8-bit value.
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* @val: The value to search
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*/
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static inline int ctpop8(uint8_t val)
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{
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#if QEMU_GNUC_PREREQ(3, 4)
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return __builtin_popcount(val);
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#else
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val = (val & 0x55) + ((val >> 1) & 0x55);
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val = (val & 0x33) + ((val >> 2) & 0x33);
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val = (val & 0x0f) + ((val >> 4) & 0x0f);
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return val;
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#endif
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}
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/**
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* ctpop16 - count the population of one bits in a 16-bit value.
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* @val: The value to search
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*/
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static inline int ctpop16(uint16_t val)
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{
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#if QEMU_GNUC_PREREQ(3, 4)
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return __builtin_popcount(val);
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#else
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val = (val & 0x5555) + ((val >> 1) & 0x5555);
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val = (val & 0x3333) + ((val >> 2) & 0x3333);
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val = (val & 0x0f0f) + ((val >> 4) & 0x0f0f);
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val = (val & 0x00ff) + ((val >> 8) & 0x00ff);
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return val;
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#endif
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}
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/**
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* ctpop32 - count the population of one bits in a 32-bit value.
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* @val: The value to search
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*/
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static inline int ctpop32(uint32_t val)
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{
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#if QEMU_GNUC_PREREQ(3, 4)
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@ -222,6 +282,10 @@ static inline int ctpop32(uint32_t val)
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#endif
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}
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/**
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* ctpop64 - count the population of one bits in a 64-bit value.
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* @val: The value to search
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*/
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static inline int ctpop64(uint64_t val)
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{
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#if QEMU_GNUC_PREREQ(3, 4)
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