Fix BigInt/UnsignedBigInt toBytes/toBits to emit minimal-length bytes#873
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Fix BigInt/UnsignedBigInt toBytes/toBits to emit minimal-length bytes#873mwaddip wants to merge 1 commit into
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BigInt and UnsignedBigInt toBytes/toBits emitted the fixed 32-byte big-endian form (to_be_bytes), but the JVM emits a minimal-length encoding: sigma's BigInt.toBytes = BigInteger.toByteArray (signed two's-complement, minimal, 0 -> [0]) and UnsignedBigInt.toBytes = BigIntegers.asUnsignedByteArray (unsigned, minimal, 0 -> []). toBits derives from the same byte sequence, so it diverged identically (256 fixed bits vs minimal x8). E.g. BigInt(127).toBytes returned 32 bytes where the JVM returns [0x7f]. Switch the four BigInt/UnsignedBigInt eval arms to to_be_vec, already the minimal form used by serialization; the fixed-width to_be_bytes is untouched. This changes only the returned value; serialization and costing are unaffected. to_bits_bigint's roundtrip reconstructs via an unsigned positional sum, valid only for non-negative values, so it is constrained to non-negative; negatives, zero, sign-pad and the unsigned arm are covered byte-exactly by new tests reconciled against the blessed v6 vectors. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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BigInt and UnsignedBigInt toBytes/toBits emitted the fixed 32-byte big-endian form (to_be_bytes), but the JVM emits a minimal-length encoding: sigma's BigInt.toBytes = BigInteger.toByteArray (signed two's-complement, minimal, 0 -> [0]) and UnsignedBigInt.toBytes = BigIntegers.asUnsignedByteArray (unsigned, minimal, 0 -> []). toBits derives from the same byte sequence, so it diverged identically (256 fixed bits vs minimal x8). E.g. BigInt(127).toBytes returned 32 bytes where the JVM returns [0x7f]. Switch the four BigInt/UnsignedBigInt eval arms to to_be_vec, already the minimal form used by serialization; the fixed-width to_be_bytes is untouched. This changes only the returned value; serialization and costing are unaffected. to_bits_bigint's roundtrip reconstructs via an unsigned positional sum, valid only for non-negative values, so it is constrained to non-negative; negatives, zero, sign-pad and the unsigned arm are covered byte-exactly by new tests reconciled against the blessed v6 vectors. Corresponds to develop PR ergoplatform#873. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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BigInt/UnsignedBigInttoBytes/toBitsemitted the fixed 32-byte form, but the JVM emits minimal-length big-endian bytes:BigInt.toBytes=BigInteger.toByteArray(signed two's-complement,0 → [0]);UnsignedBigInt.toBytes=asUnsignedByteArray(unsigned,0 → []).toBitsderives from the same bytes, so it diverged too (e.g.BigInt(127).toByteswas 32 bytes vs[0x7f]).Fix: the four eval arms now use
to_be_vec— the minimal form serialization already uses;to_be_bytesis untouched. Output-only; serialization and costing unaffected. Tests assert byte/bit-exact output against the blessed v6 vectors (zero, sign-pad, negatives, empty unsigned).