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author | Kiran Ostrolenk <kiran.ostrolenk@codethink.co.uk> | 2023-04-28 15:47:48 +0100 |
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committer | Richard Henderson <richard.henderson@linaro.org> | 2023-05-02 13:05:45 -0700 |
commit | 31fe256d32d70c83232c68c6e2d136b533e1dda0 (patch) | |
tree | d61c40c278a3e7908ddc20f2bd2343de683b88f9 | |
parent | 8841c815a93a2da3e60fb8173d9c5dc01f552dab (diff) | |
download | qemu-31fe256d32d70c83232c68c6e2d136b533e1dda0.zip qemu-31fe256d32d70c83232c68c6e2d136b533e1dda0.tar.gz qemu-31fe256d32d70c83232c68c6e2d136b533e1dda0.tar.bz2 |
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 <kiran.ostrolenk@codethink.co.uk>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20230428144757.57530-11-lawrence.hunter@codethink.co.uk>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
-rw-r--r-- | include/qemu/host-utils.h | 54 |
1 files changed, 54 insertions, 0 deletions
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 * |