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[wip] refactor checking of RS code validity

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This commit is contained in:
Michael Bradley, Jr 2022-03-15 20:32:37 -05:00
parent 0d2fae23bf
commit 6e965bda8e
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2 changed files with 42 additions and 39 deletions
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14
leopard.nim
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@ -16,6 +16,8 @@ const
LeopardNotEnoughDataMsg = "Buffer counts are too low"
MinBufferSize* = 64.uint
MinSymbols* = 1.uint
MaxTotalSymbols* = 65536.uint
type
Data* = seq[seq[byte]]
@ -61,11 +63,17 @@ type
# data symbols = 239
# parity symbols = 255 - 239 = 16
func isValid*(code: ReedSolomonCode): bool =
not ((code.codeword - code.data != code.parity) or
(code.parity > code.data) or (code.codeword < MinSymbols + 1) or
(code.data < MinSymbols) or (code.parity < MinSymbols) or
(code.codeword > MaxTotalSymbols))
proc RS*(codeword, data: Positive): ReedSolomonCode =
var
parity = codeword - data
if parity <= 0: parity = 0
if parity < 0: parity = 0
(codeword: codeword.uint, data: data.uint, parity: parity.uint)
when (NimMajor, NimMinor, NimPatch) < (1, 4, 0):
@ -116,7 +124,7 @@ proc leoInit*() =
proc encode*(code: ReedSolomonCode, data: Data):
Result[ParityData, LeopardError] =
if code.parity < 1 or code.parity > code.data:
if not code.isValid:
return err LeopardError(code: LeopardBadCode, msg: LeopardBadCodeMsg)
var
@ -194,7 +202,7 @@ proc encode*(code: ReedSolomonCode, data: Data):
proc decode*(code: ReedSolomonCode, data: Data, parityData: ParityData,
symbolBytes: uint): Result[Data, LeopardError] =
if code.parity < 1 or code.parity > code.data:
if not code.isValid:
return err LeopardError(code: LeopardBadCode, msg: LeopardBadCodeMsg)
var

67
tests/test_leopard.nim
View File

@ -19,6 +19,33 @@ proc genData(outerLen, innerLen: uint): Data =
var
initialized = false
suite "Helpers":
test "isValid should return false if RS code is nonsensical or is invalid per Leopard-RS":
var
rsCode = (codeword: 8.uint, data: 5.uint, parity: 1.uint)
check: not rsCode.isValid
rsCode = RS(110,10)
check: not rsCode.isValid
rsCode = RS(1,1)
check: not rsCode.isValid
rsCode = (codeword: 2.uint, data: 0.uint, parity: 2.uint)
check: not rsCode.isValid
rsCode = RS(2,2)
check: not rsCode.isValid
rsCode = RS(65537,65409)
check: not rsCode.isValid
suite "Initialization":
test "encode and decode should fail if Leopard-RS is not initialized":
let
@ -53,7 +80,7 @@ suite "Initialization":
check: initialized
suite "Encoder":
test "should fail if RS code is nonsensical or is so per Leopard-RS":
test "should fail if RS code is nonsensical or is invalid per Leopard-RS":
check: initialized
if not initialized: return
@ -61,7 +88,7 @@ suite "Encoder":
symbolBytes = MinBufferSize
var
rsCode = RS(5,5)
rsCode = RS(110,10)
data = genData(rsCode.data, symbolBytes)
encodeRes = rsCode.encode data
@ -69,22 +96,6 @@ suite "Encoder":
if encodeRes.isErr:
check: encodeRes.error.code == LeopardBadCode
rsCode = RS(5,10)
data = genData(rsCode.data, symbolBytes)
encodeRes = rsCode.encode data
check: encodeRes.isErr
if encodeRes.isErr:
check: encodeRes.error.code == LeopardBadCode
rsCode = RS(110,10)
data = genData(rsCode.data, symbolBytes)
encodeRes = rsCode.encode data
check: encodeRes.isErr
if encodeRes.isErr:
check: encodeRes.error.code == LeopardBadCode
test "should fail if outer length of data does not match the RS code":
check: initialized
if not initialized: return
@ -185,7 +196,7 @@ suite "Encoder":
check: encodeRes.isOk
suite "Decoder":
test "should fail if RS code is nonsensical or is so per Leopard-RS":
test "should fail if RS code is nonsensical or is invalid per Leopard-RS":
check: initialized
if not initialized: return
@ -193,7 +204,7 @@ suite "Decoder":
symbolBytes = MinBufferSize
var
rsCode = RS(5,5)
rsCode = RS(110,10)
data = genData(rsCode.data, symbolBytes)
parityData: ParityData
decodeRes = rsCode.decode(data, parityData, symbolBytes)
@ -202,22 +213,6 @@ suite "Decoder":
if decodeRes.isErr:
check: decodeRes.error.code == LeopardBadCode
rsCode = RS(5,10)
data = genData(rsCode.data, symbolBytes)
decodeRes = rsCode.decode(data, parityData, symbolBytes)
check: decodeRes.isErr
if decodeRes.isErr:
check: decodeRes.error.code == LeopardBadCode
rsCode = RS(110,10)
data = genData(rsCode.data, symbolBytes)
decodeRes = rsCode.decode(data, parityData, symbolBytes)
check: decodeRes.isErr
if decodeRes.isErr:
check: decodeRes.error.code == LeopardBadCode
test "should fail if outer length of data does not match the RS code":
check: initialized
if not initialized: return