Fixed rebasing

Resolved scary activation flag duplication; activation logic is now solely in GetNextBlockScriptFlags, as per @markblundeberg‘s refactoring (D5220).

Moved the comment about FIRST_UNDEFINED_OP_VALUE.

Resolved lint issues

Rebased onto master

Updated comments

Removed empty line in interpreter.cpp. Fused loops in op_reversebytes_test.cpp and other refactorings, expanded palindromes test vector.

Fixed the, and I quote, quibble, which has been pointed out by @markblundeberg

That fixed it. Thanks Mark!

Rebased onto the changes from master.

In D4871#119436, @teamcity wrote:

Build Bitcoin-ABC / Diffs / Diff Testing failed.

Snippet of first build failure:

[17:32:02]W:	 [Step 1/1] + case "$ABC_BUILD_NAME" in
[17:32:02] :	 [Step 1/1] Error: Invalid build name 'build-diff'
[17:32:02]W:	 [Step 1/1] + echo 'Error: Invalid build name '\''build-diff'\'''
[17:32:02]W:	 [Step 1/1] + exit 2
[17:32:02]W:	 [Step 1/1] Process exited with code 2
[17:32:02]E:	 [Step 1/1] Process exited with code 2 (Step: Command Line)

This seems like a configuration error. Does someone know what‘s going on there?

Renamed opcode to OP_REVERSEBYTES (which is the final name now), refactored & amended tests.

In D4871#118376, @Mengerian wrote:

In D4871#117783, @tobias_ruck wrote:

Renamed to OP_ENDIAN_REVERSE, reasons can be found in the PR:

In a previous proposal, this opcode has been named OP_REVERSE. After that, it has been renamed to OP_BSWAP, as that is a more technically accurate term, which is commonly used for reversing the byteorder of integers [14] [15]. However, after some more consideration, it has been renamed to OP_ENDIAN_REVERSE following Boost‘s nomenclature [16]. This is because OP_BSWAP is lexically very similar to the already existing OP_SWAP and would make Script harder to read. Also, while the technical term for the instruction is indeed bswap, it isn‘t well known for developers of higher level languages and could thus spark confusion that would be avoided by using the name OP_ENDIAN_REVERSE, which is more self-descriptive.

Also added tests for unexecuted branches, clarified tests for not yet activated case.

Merged D4859 into this diff.

I'm not a fan of the new name... "Endian" to me seems hardware specific, and usually implies some power-of-2 number of bytes.... If you're worried about confusion, using the word "Endian" to me seems more confusing. It's possible people may use for things other than endian conversion, since it can reverse the byte order for any arbitrary-length string.

How about "OP_REVERSE_BYTES", or "OP_BYTE_SWAP"?

In any case, I guess this is a bit bike-sheddy, so not super-important either way.

Collapsed reversed_data generation code.

Accidentially updated wrong diff....

Collapsed reversed_data generation code.

Renamed to OP_ENDIAN_REVERSE, reasons can be found in the PR:

will be merged with D4871

moved to D4871

Coordinated SCRIPT_ENABLE_OP_BSWAP script flag bit with @markblundeberg

Renamed bswap_opcode_tests.cpp to op_bswap_tests.cpp

Squashed commits into one (commit amend failed previously)

I‘ve left the SCRIPT_ENABLE_OP_BSWAP flag at bit 22, this should be coordinated with @markblundeberg

Applied review by @deadalnix. T707

Added OP_BSWAP opcode without tests or behavior.

Fixed OP_BSWAP opcode number in script.py