From 31fe256d32d70c83232c68c6e2d136b533e1dda0 Mon Sep 17 00:00:00 2001 From: Kiran Ostrolenk Date: Fri, 28 Apr 2023 15:47:48 +0100 Subject: qemu/host-utils.h: Add clz and ctz functions for lower-bit integers This is for use in the RISC-V vclz and vctz instructions (implemented in proceeding commit). Signed-off-by: Kiran Ostrolenk Reviewed-by: Richard Henderson Message-Id: <20230428144757.57530-11-lawrence.hunter@codethink.co.uk> Signed-off-by: Richard Henderson --- include/qemu/host-utils.h | 54 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 54 insertions(+) (limited to 'include') diff --git a/include/qemu/host-utils.h b/include/qemu/host-utils.h index 3ce62bf..d3b4dce 100644 --- a/include/qemu/host-utils.h +++ b/include/qemu/host-utils.h @@ -108,6 +108,36 @@ static inline uint64_t muldiv64(uint64_t a, uint32_t b, uint32_t c) #endif /** + * clz8 - count leading zeros in a 8-bit value. + * @val: The value to search + * + * Returns 8 if the value is zero. Note that the GCC builtin is + * undefined if the value is zero. + * + * Note that the GCC builtin will upcast its argument to an `unsigned int` + * so this function subtracts off the number of prepended zeroes. + */ +static inline int clz8(uint8_t val) +{ + return val ? __builtin_clz(val) - 24 : 8; +} + +/** + * clz16 - count leading zeros in a 16-bit value. + * @val: The value to search + * + * Returns 16 if the value is zero. Note that the GCC builtin is + * undefined if the value is zero. + * + * Note that the GCC builtin will upcast its argument to an `unsigned int` + * so this function subtracts off the number of prepended zeroes. + */ +static inline int clz16(uint16_t val) +{ + return val ? __builtin_clz(val) - 16 : 16; +} + +/** * clz32 - count leading zeros in a 32-bit value. * @val: The value to search * @@ -154,6 +184,30 @@ static inline int clo64(uint64_t val) } /** + * ctz8 - count trailing zeros in a 8-bit value. + * @val: The value to search + * + * Returns 8 if the value is zero. Note that the GCC builtin is + * undefined if the value is zero. + */ +static inline int ctz8(uint8_t val) +{ + return val ? __builtin_ctz(val) : 8; +} + +/** + * ctz16 - count trailing zeros in a 16-bit value. + * @val: The value to search + * + * Returns 16 if the value is zero. Note that the GCC builtin is + * undefined if the value is zero. + */ +static inline int ctz16(uint16_t val) +{ + return val ? __builtin_ctz(val) : 16; +} + +/** * ctz32 - count trailing zeros in a 32-bit value. * @val: The value to search * -- cgit v1.1