Functions
uint32_t	Hash32 (const void *data, size_t bytes, uint32_t seed)

uint64_t	Hash64 (const void *data, size_t bytes, uint64_t seed)

static uint32_t	Mix (uint32_t hash)

static uint32_t	CheapMix (uint32_t hash)

Detailed Description

Our hash functions are exposed as SK_SPI (e.g. SkParagraph)

Function Documentation

◆ CheapMix()

static uint32_t SkChecksum::CheapMix ( uint32_t hash )

inlinestatic

uint32_t -> uint32_t hash, useful for when you're about to truncate this hash but you suspect its low bits aren't well mixed.

This version is 2-lines cheaper than Mix, but seems to be sufficient for the font cache.

Definition at line 45 of file SkChecksum.h.

                                                   {
        hash ^= hash >> 16;
        hash *= 0x85ebca6b;
        hash ^= hash >> 16;
        return hash;
    }

◆ Hash32()

uint32_t SK_SPI SkChecksum::Hash32	(	const void *	data,
		size_t	bytes,
		uint32_t	seed = `0`
	)

This is a fast, high-quality 32-bit hash. We make no guarantees about this remaining stable over time, or being consistent across devices.

For now, this is a 64-bit wyhash, truncated to 32-bits. See: https://github.com/wangyi-fudan/wyhash

Definition at line 113 of file SkChecksum.cpp.

                                                               {
    return static_cast<uint32_t>(wyhash(data, bytes, seed, _wyp));
}

◆ Hash64()

uint64_t SK_SPI SkChecksum::Hash64	(	const void *	data,
		size_t	bytes,
		uint64_t	seed = `0`
	)

This is a fast, high-quality 64-bit hash. We make no guarantees about this remaining stable over time, or being consistent across devices.

For now, this is a 64-bit wyhash. See: https://github.com/wangyi-fudan/wyhash

Definition at line 117 of file SkChecksum.cpp.

                                                               {
    return wyhash(data, bytes, seed, _wyp);
}

◆ Mix()

static uint32_t SkChecksum::Mix ( uint32_t hash )