go/src/internal/chacha8rand/chacha8_generic.go

// setup sets up 4 ChaCha8 blocks in b32 with the counter and seed.
// Note that b32 is [16][4]uint32 not [4][16]uint32: the blocks are interlaced
// the same way they would be in a 4-way SIMD implementations.
func setup(seed *[4]uint64, b32 *[16][4]uint32, counter uint32) { … }

func _() { … }

// block_generic is the non-assembly block implementation,
// for use on systems without special assembly.
// Even on such systems, it is quite fast: on GOOS=386,
// ChaCha8 using this code generates random values faster than PCG-DXSM.
func block_generic(seed *[4]uint64, buf *[32]uint64, counter uint32) { … }

// qr is the (inlinable) ChaCha8 quarter round.
func qr(a, b, c, d uint32) (_a, _b, _c, _d uint32) { … }