Types

Limbs[N] = array[N, Word]

Limbs type. Source Edit

SignedWord = int64

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SomeBigInteger[bits] = StUint[bits] | StInt[bits]

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StInt[bits] = object
  impl*: StUint[bits]

Stack-based integer.

Signed, in two complement format

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StUint[bits] = object
  limbs*: array[bits.wordsRequired, Word]

Stack-based integer.

Unsigned.

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uint128 {.importc: "unsigned __int128", nodecl.} = object

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Word = uint64

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Consts

func copyWords(a: var openArray[Word]; startA: int; b: openArray[Word]; startB: int; numWords: int) {....raises: [], inline, noinit, ...gcsafe, tags: [], forbids: [].}: Copy a slice of B into A. This properly deals with overlaps when A and B are slices of the same buffer. Source Edit
func usedBitsAndWords(a: openArray[Word]): tuple[bits, words: int] {....raises: [], inline, noinit, ...gcsafe, tags: [], forbids: [].}: Returns the number of used words and bits in a bigInt.

Returns (0, 0) for all-zeros array (even if technically you need 1 bit and 1 word to encode zero).
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func wordsRequired(bits: int): int {.compileTime, ...raises: [], tags: [], forbids: [].}: Compute the number of limbs required for the announced bit length. Source Edit

macro staticFor(idx: untyped{nkIdent}; start, stopEx: static int; body: untyped): untyped {. ...deprecated: "stew/staticfor".}: Deprecated: stew/staticfor
staticFor [min inclusive, max exclusive). Source Edit

template `[]`(a: StInt; i: SomeInteger or BackwardsIndex): Word: Source Edit
template `[]`(a: StUint; i: SomeInteger or BackwardsIndex): Word: Source Edit
template `[]=`(a: var StInt; i: SomeInteger or BackwardsIndex; val: Word): Source Edit
template `[]=`(a: var StUint; i: SomeInteger or BackwardsIndex; val: Word): Source Edit
template clearExtraBitsOverMSB(a: var StUint | StInt) {..}: A StUint is stored in an array of 32 of 64-bit word.

If we do bit manipulation at the word level, for example a 8-bit StUint stored in a 64-bit word, we need to clear the upper 56-bit.
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template len(a: StInt): int: Source Edit
template len(a: StUint): int: Source Edit
template limbs(a: StInt): untyped: Source Edit