mirror of
https://github.com/superseriousbusiness/gotosocial.git
synced 2024-11-01 06:50:00 +00:00
286 lines
6.1 KiB
Go
286 lines
6.1 KiB
Go
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package blake3
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import (
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"math/bits"
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"unsafe"
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"github.com/zeebo/blake3/internal/alg"
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"github.com/zeebo/blake3/internal/consts"
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"github.com/zeebo/blake3/internal/utils"
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)
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//
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// hasher contains state for a blake3 hash
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//
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type hasher struct {
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len uint64
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chunks uint64
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flags uint32
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key [8]uint32
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stack cvstack
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buf [8192]byte
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}
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func (a *hasher) reset() {
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a.len = 0
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a.chunks = 0
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a.stack.occ = 0
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a.stack.lvls = [8]uint8{}
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a.stack.bufn = 0
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}
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func (a *hasher) update(buf []byte) {
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// relies on the first two words of a string being the same as a slice
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a.updateString(*(*string)(unsafe.Pointer(&buf)))
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}
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func (a *hasher) updateString(buf string) {
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var input *[8192]byte
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for len(buf) > 0 {
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if a.len == 0 && len(buf) > 8192 {
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// relies on the data pointer being the first word in the string header
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input = (*[8192]byte)(*(*unsafe.Pointer)(unsafe.Pointer(&buf)))
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buf = buf[8192:]
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} else if a.len < 8192 {
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n := copy(a.buf[a.len:], buf)
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a.len += uint64(n)
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buf = buf[n:]
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continue
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} else {
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input = &a.buf
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}
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a.consume(input)
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a.len = 0
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a.chunks += 8
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}
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}
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func (a *hasher) consume(input *[8192]byte) {
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var out chainVector
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var chain [8]uint32
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alg.HashF(input, 8192, a.chunks, a.flags, &a.key, &out, &chain)
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a.stack.pushN(0, &out, 8, a.flags, &a.key)
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}
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func (a *hasher) finalize(p []byte) {
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var d Digest
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a.finalizeDigest(&d)
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_, _ = d.Read(p)
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}
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func (a *hasher) finalizeDigest(d *Digest) {
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if a.chunks == 0 && a.len <= consts.ChunkLen {
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compressAll(d, a.buf[:a.len], a.flags, a.key)
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return
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}
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d.chain = a.key
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d.flags = a.flags | consts.Flag_ChunkEnd
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if a.len > 64 {
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var buf chainVector
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alg.HashF(&a.buf, a.len, a.chunks, a.flags, &a.key, &buf, &d.chain)
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if a.len > consts.ChunkLen {
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complete := (a.len - 1) / consts.ChunkLen
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a.stack.pushN(0, &buf, int(complete), a.flags, &a.key)
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a.chunks += complete
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a.len = uint64(copy(a.buf[:], a.buf[complete*consts.ChunkLen:a.len]))
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}
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}
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if a.len <= 64 {
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d.flags |= consts.Flag_ChunkStart
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}
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d.counter = a.chunks
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d.blen = uint32(a.len) % 64
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base := a.len / 64 * 64
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if a.len > 0 && d.blen == 0 {
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d.blen = 64
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base -= 64
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}
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if consts.IsLittleEndian {
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copy((*[64]byte)(unsafe.Pointer(&d.block[0]))[:], a.buf[base:a.len])
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} else {
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var tmp [64]byte
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copy(tmp[:], a.buf[base:a.len])
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utils.BytesToWords(&tmp, &d.block)
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}
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for a.stack.bufn > 0 {
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a.stack.flush(a.flags, &a.key)
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}
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var tmp [16]uint32
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for occ := a.stack.occ; occ != 0; occ &= occ - 1 {
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col := uint(bits.TrailingZeros64(occ)) % 64
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alg.Compress(&d.chain, &d.block, d.counter, d.blen, d.flags, &tmp)
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*(*[8]uint32)(unsafe.Pointer(&d.block[0])) = a.stack.stack[col]
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*(*[8]uint32)(unsafe.Pointer(&d.block[8])) = *(*[8]uint32)(unsafe.Pointer(&tmp[0]))
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if occ == a.stack.occ {
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d.chain = a.key
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d.counter = 0
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d.blen = consts.BlockLen
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d.flags = a.flags | consts.Flag_Parent
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}
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}
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d.flags |= consts.Flag_Root
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}
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//
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// chain value stack
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//
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type chainVector = [64]uint32
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type cvstack struct {
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occ uint64 // which levels in stack are occupied
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lvls [8]uint8 // what level the buf input was in
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bufn int // how many pairs are loaded into buf
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buf [2]chainVector
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stack [64][8]uint32
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}
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func (a *cvstack) pushN(l uint8, cv *chainVector, n int, flags uint32, key *[8]uint32) {
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for i := 0; i < n; i++ {
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a.pushL(l, cv, i)
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for a.bufn == 8 {
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a.flush(flags, key)
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}
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}
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}
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func (a *cvstack) pushL(l uint8, cv *chainVector, n int) {
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bit := uint64(1) << (l & 63)
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if a.occ&bit == 0 {
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readChain(cv, n, &a.stack[l&63])
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a.occ ^= bit
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return
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}
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a.lvls[a.bufn&7] = l
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writeChain(&a.stack[l&63], &a.buf[0], a.bufn)
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copyChain(cv, n, &a.buf[1], a.bufn)
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a.bufn++
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a.occ ^= bit
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}
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func (a *cvstack) flush(flags uint32, key *[8]uint32) {
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var out chainVector
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alg.HashP(&a.buf[0], &a.buf[1], flags|consts.Flag_Parent, key, &out, a.bufn)
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bufn, lvls := a.bufn, a.lvls
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a.bufn, a.lvls = 0, [8]uint8{}
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for i := 0; i < bufn; i++ {
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a.pushL(lvls[i]+1, &out, i)
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}
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}
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//
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// helpers to deal with reading/writing transposed values
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//
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func copyChain(in *chainVector, icol int, out *chainVector, ocol int) {
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type u = uintptr
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type p = unsafe.Pointer
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type a = *uint32
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i := p(u(p(in)) + u(icol*4))
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o := p(u(p(out)) + u(ocol*4))
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*a(p(u(o) + 0*32)) = *a(p(u(i) + 0*32))
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*a(p(u(o) + 1*32)) = *a(p(u(i) + 1*32))
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*a(p(u(o) + 2*32)) = *a(p(u(i) + 2*32))
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*a(p(u(o) + 3*32)) = *a(p(u(i) + 3*32))
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*a(p(u(o) + 4*32)) = *a(p(u(i) + 4*32))
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*a(p(u(o) + 5*32)) = *a(p(u(i) + 5*32))
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*a(p(u(o) + 6*32)) = *a(p(u(i) + 6*32))
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*a(p(u(o) + 7*32)) = *a(p(u(i) + 7*32))
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}
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func readChain(in *chainVector, col int, out *[8]uint32) {
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type u = uintptr
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type p = unsafe.Pointer
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type a = *uint32
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i := p(u(p(in)) + u(col*4))
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out[0] = *a(p(u(i) + 0*32))
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out[1] = *a(p(u(i) + 1*32))
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out[2] = *a(p(u(i) + 2*32))
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out[3] = *a(p(u(i) + 3*32))
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out[4] = *a(p(u(i) + 4*32))
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out[5] = *a(p(u(i) + 5*32))
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out[6] = *a(p(u(i) + 6*32))
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out[7] = *a(p(u(i) + 7*32))
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}
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func writeChain(in *[8]uint32, out *chainVector, col int) {
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type u = uintptr
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type p = unsafe.Pointer
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type a = *uint32
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o := p(u(p(out)) + u(col*4))
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*a(p(u(o) + 0*32)) = in[0]
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*a(p(u(o) + 1*32)) = in[1]
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*a(p(u(o) + 2*32)) = in[2]
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*a(p(u(o) + 3*32)) = in[3]
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*a(p(u(o) + 4*32)) = in[4]
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*a(p(u(o) + 5*32)) = in[5]
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*a(p(u(o) + 6*32)) = in[6]
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*a(p(u(o) + 7*32)) = in[7]
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}
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//
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// compress <= chunkLen bytes in one shot
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//
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func compressAll(d *Digest, in []byte, flags uint32, key [8]uint32) {
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var compressed [16]uint32
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d.chain = key
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d.flags = flags | consts.Flag_ChunkStart
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for len(in) > 64 {
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buf := (*[64]byte)(unsafe.Pointer(&in[0]))
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var block *[16]uint32
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if consts.IsLittleEndian {
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block = (*[16]uint32)(unsafe.Pointer(buf))
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} else {
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block = &d.block
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utils.BytesToWords(buf, block)
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}
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alg.Compress(&d.chain, block, 0, consts.BlockLen, d.flags, &compressed)
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d.chain = *(*[8]uint32)(unsafe.Pointer(&compressed[0]))
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d.flags &^= consts.Flag_ChunkStart
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in = in[64:]
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}
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if consts.IsLittleEndian {
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copy((*[64]byte)(unsafe.Pointer(&d.block[0]))[:], in)
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} else {
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var tmp [64]byte
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copy(tmp[:], in)
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utils.BytesToWords(&tmp, &d.block)
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}
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d.blen = uint32(len(in))
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d.flags |= consts.Flag_ChunkEnd | consts.Flag_Root
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}
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