98 lines
3.6 KiB
Nim
98 lines
3.6 KiB
Nim
# nimbus-eth1
|
|
# Copyright (c) 2023-2024 Status Research & Development GmbH
|
|
# Licensed under either of
|
|
# * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or
|
|
# http://www.apache.org/licenses/LICENSE-2.0)
|
|
# * MIT license ([LICENSE-MIT](LICENSE-MIT) or
|
|
# http://opensource.org/licenses/MIT)
|
|
# at your option. This file may not be copied, modified, or distributed
|
|
# except according to those terms.
|
|
|
|
{.push raises: [].}
|
|
|
|
import
|
|
std/sequtils,
|
|
eth/common,
|
|
results,
|
|
./aristo_desc
|
|
|
|
# Info snippet (just a reminder to keep somewhere)
|
|
#
|
|
# Extension of a compact encoded as prefixed sequence of nibbles (i.e.
|
|
# half bytes with 4 bits.)
|
|
#
|
|
# pfx | bits | vertex type | layout
|
|
# ----+ -----+-------------+----------------------------------------
|
|
# 0 | 0000 | extension | @[<pfx, ignored>, nibble-pair, ..]
|
|
# 1 | 0001 | extension | @[<pfx, first-nibble>, nibble-pair, ..]
|
|
# 2 | 0010 | leaf | @[<pfx, ignored>, nibble-pair, ..]
|
|
# 3 | 0011 | leaf | @[<pfx, first-nibble>, nibble-pair, ..]
|
|
#
|
|
# where the `ignored` part is typically expected a zero nibble.
|
|
|
|
func pathPfxPad*(pfx: NibblesBuf; dblNibble: static[byte]): NibblesBuf
|
|
|
|
# ------------------------------------------------------------------------------
|
|
# Public functions
|
|
# ------------------------------------------------------------------------------
|
|
|
|
func pathAsBlob*(tag: PathID): Blob =
|
|
## Convert the `tag` argument to a sequence of an even number of nibbles
|
|
## represented by a `Blob`. If the argument `tag` represents an odd number
|
|
## of nibbles, a zero nibble is appendend.
|
|
##
|
|
## This function is useful only if there is a tacit agreement that all paths
|
|
## used to index database leaf values can be represented as `Blob`, i.e.
|
|
## `PathID` type paths with an even number of nibbles.
|
|
if 0 < tag.length:
|
|
let key = tag.pfx.toBytesBE
|
|
if 64 <= tag.length:
|
|
return @key
|
|
else:
|
|
return key[0 .. (tag.length - 1) div 2]
|
|
|
|
func pathToTag*(partPath: NibblesBuf): Result[PathID,AristoError] =
|
|
## Convert the argument `partPath` to a `PathID` type value.
|
|
if partPath.len == 0:
|
|
return ok VOID_PATH_ID
|
|
if partPath.len <= 64:
|
|
return ok PathID(
|
|
pfx: UInt256.fromBytesBE partPath.pathPfxPad(0).getBytes(),
|
|
length: partPath.len.uint8)
|
|
err(PathAtMost64Nibbles)
|
|
|
|
func pathToTag*(partPath: openArray[byte]): Result[PathID,AristoError] =
|
|
## Variant of `pathToTag()`
|
|
if partPath.len == 0:
|
|
return ok VOID_PATH_ID
|
|
if partPath.len <= 32:
|
|
return ok PathID(
|
|
pfx: UInt256.fromBytesBE @partPath & 0u8.repeat(32-partPath.len),
|
|
length: 2 * partPath.len.uint8)
|
|
err(PathAtMost64Nibbles)
|
|
|
|
# --------------------
|
|
|
|
func pathPfxPad*(pfx: NibblesBuf; dblNibble: static[byte]): NibblesBuf =
|
|
## Extend (or cut) the argument nibbles sequence `pfx` for generating a
|
|
## `NibblesBuf` with exactly 64 nibbles, the equivalent of a path key.
|
|
##
|
|
## This function must be handled with some care regarding a meaningful value
|
|
## for the `dblNibble` argument. Currently, only static values `0` and `255`
|
|
## are allowed for padding. This is checked at compile time.
|
|
static:
|
|
doAssert dblNibble == 0 or dblNibble == 255
|
|
|
|
let padLen = 64 - pfx.len
|
|
if 0 <= padLen:
|
|
result = pfx & NibblesBuf.fromBytes(dblNibble.repeat(padLen div 2).mapIt(it.byte))
|
|
if (padLen and 1) == 1:
|
|
result = result & NibblesBuf.nibble(dblNibble.byte)
|
|
else:
|
|
let nope = NibblesBuf()
|
|
result = pfx.slice(0,64) & nope # nope forces re-alignment
|
|
|
|
# ------------------------------------------------------------------------------
|
|
# End
|
|
# ------------------------------------------------------------------------------
|