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Fix 8x bigger than necessary encoding size of miniscalars in scalar mul

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Mamy André-Ratsimbazafy 2020-08-24 18:31:27 +02:00
parent 442c3f6cf6
commit 00ff599106
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1 changed files with 8 additions and 8 deletions
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16
constantine/elliptic/ec_endomorphism_accel.nim
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@ -49,7 +49,7 @@ import
# (For example generating a public-key)
type
Recoded[LengthInDigits: static int] = distinct array[LengthInDigits, byte]
Recoded[LengthInDigits: static int] = distinct array[(LengthInDigits + 7) div 8, byte]
GLV_SAC[M, LengthInDigits: static int] = array[M, Recoded[LengthInDigits]]
## GLV-Based Sign-Aligned-Column representation
## see Faz-Hernandez, 2013
@ -69,9 +69,9 @@ type
const
BitSize = 1
Shift = 1 # log2(2) - we can store 2 digits per byte
ByteMask = 1 # we need (mod 2) to access a packed bytearray
DigitMask = 0b1 # Digits take 1-bit
Shift = 3 # log2(sizeof(byte) * 8) - Find the word to read/write
WordMask = sizeof(byte) * 8 - 1 # - In the word, shift to the offset to read/write
DigitMask = 1 shl BitSize - 1 # Digits take 1-bit - Once at location, isolate bits to read/write
proc `[]`(recoding: Recoded,
digitIdx: int): uint8 {.inline.}=
@ -81,9 +81,9 @@ proc `[]`(recoding: Recoded,
assert digitIdx < len
let slot = distinctBase(recoding)[
len-1 - (digitIdx shr Shift)
(len-1 - digitIdx) shr Shift
]
let recoded = slot shr (BitSize*(digitIdx and ByteMask)) and DigitMask
let recoded = slot shr (BitSize*(digitIdx and WordMask)) and DigitMask
return recoded
proc `[]=`(recoding: var Recoded,
@ -95,10 +95,10 @@ proc `[]=`(recoding: var Recoded,
assert digitIdx < Recoded.LengthInDigits
let slot = distinctBase(recoding)[
len-1 - (digitIdx shr Shift)
(len-1 - digitIdx) shr Shift
].addr
let shifted = byte((value and DigitMask) shl (BitSize*(digitIdx and ByteMask)))
let shifted = byte((value and DigitMask) shl (BitSize*(digitIdx and WordMask)))
slot[] = slot[] or shifted
func nDimMultiScalarRecoding[M, L: static int](