Write an unnamed opcode in ASM as its raw byte, 0xba - #4
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@smartledger/bsv 9.11.1 writes an opcode with no name as 0xba and reads it back from ASM. exactAsm wrote OP_UNKNOWN186, which nothing reads, so it refused any script holding one. It now writes 0xba; the read-back check still refuses such scripts where an older @smartledger/bsv is installed. Tests run against 9.11.1.
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This was referenced Sep 17, 2026
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toASM and toString wrote nothing for an empty data push. For one encoded with
OP_PUSHDATA1/2/4 (4c00), ASM dropped the push, so 514c0051 read back as 5151,
one stack element fewer, and toString wrote a bare OP_PUSHDATA1 that
fromString could not read. The empty push Script#add(Buffer.alloc(0)) builds,
and so buildDataOut(''), serializes to 0x00 but was written as nothing, so
6a00 read back as 6a.
ASM now writes an empty push minimally, as 0. toString writes
OP_PUSHDATA1 0 0x for the PUSHDATA encodings, which fromString already read,
and OP_0 otherwise, as it already did for 0x00 parsed from bytes. Four tests
had pinned the invisible form; they now assert the text reads back.
No reader changes. Of 4,000 generated scripts, the 909 whose text changed all
contain an empty push and all read back exactly; every text 9.11.1 wrote is
read the same way.
Reported in codenlighten/scriptmin#4.
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Follow-up to #3, after @smartledger/bsv 9.11.1 (codenlighten/smartledger-bsv#175).
Change
toAsm(ops, { bare: true }), and soexactAsmand--asm -o, writes an opcode with no name (0xba–0xfc) as0xba, the form bsv 9.11.1 writes and reads. It used to writeOP_UNKNOWN186, which nothing reads, so every such script was refused.fromASM('0xba')throws, so the script is still refused, and the message now says which version reads it back.--explain,--jsonrewrites) still showsOP_UNKNOWN186.^9.11.1, so CI tests against it. The peer range stays^9.10.1.Tests
51ba6a05aabbccddee→OP_1 0xba OP_RETURN aabbccddee, and it reads back byte for byte.npm test: 28/28 on 9.11.1.Review of bsv 9.11.1 (#175)
Round-trip fuzz against the npm 9.11.1 package: every unnamed opcode, direct/
OP_PUSHDATA1/OP_PUSHDATA2/OP_PUSHDATA4pushes,OP_0, and the empty script.toASM→fromASM(29k scripts with minimal pushes)toString→fromString(29k scripts)toString→fromString, no emptyOP_PUSHDATA(25.5k)Every remaining
toStringfailure has the same cause, and 9.11.0 has it too: an empty push written withOP_PUSHDATA1/2/4(4c00) prints as a bareOP_PUSHDATA1with no length or data.fromStringthen throws (Cannot read properties of undefined (reading 'slice')orPushdata data must start with 0x) or misreads the next token. Writing it asOP_PUSHDATA1 0 0xwould needfromStringto accept an empty0x.