[am-official]

Closes #38

Changes

• Lexer: << and >> added to the OP pattern, ahead of <=/>= and the single-character operators.
• Parser: a new parse_shift level between relational and additive, following C precedence: x << 2 + 1 is x << 3, y << 1 < 7 is (y << 1) < 7, and shifts are left-associative.
• Constant folding: _fold_binary folds << and >> on literals to 8-bit results (0x81 << 1 gives 2).
• Code generation (gen_expr):
  • Literal count: unrolled LSL R16 / LSR R16. A count of 8 or more loads 0 directly instead of emitting 8+ instructions (e.g. x << 200).
  • Variable count: a small loop that tests R17 (CPI R17, 0 / BREQ), shifts once, and does DEC R17. A count of 0 leaves the value unchanged.
  • >> uses LSR (logical), as the issue asks, so 0x81 >> 7 is 1.
• README: shifts listed among the C features.

Tests

New tests in tests/test_compiler.py compile, assemble and run programs on the CPU. They cover:

• literal shifts, including 0, 7, and 8 or more
• variable shifts, including counts of 0 and 8
• precedence and associativity
• constant folding
• the unrolled output and the >= 8 short cut

The tests write their results to 0xC0 and up, because the compiler allocates variables from 0x60.

• pytest: 282 passed (276 before, plus 6)
• ruff check and ruff format --check are clean on both changed files. ruff check . still reports the 2 issues that are already on main in other files.
• Mutation checks: each of these makes tests fail:
  • ASR in place of LSR
  • dropping the new precedence level
  • a wrong >> fold
  • removing the >= 8 short cut
  • dropping DEC R17

[sql-hkr]

LGTM! Thank you for the contribution!

[codecov]

Codecov Report

❌ Patch coverage is 97.22222% with 1 line in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
src/tiny8/compiler.py	97.22%	1 Missing ⚠️

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