FA-89513 / Instruction set emulation / Member archive

Every stored byte receives the low byte · case 03

sw and sh replicate the least significant byte across the whole access.

Member previewVariant 3 · 3 implementations · 8 checks per implementation

Case contract

Input [mem, ops]: mem is a byte list; ops [op, addr, value] with lb/lbu/lh/lhu/lw loads and sb/sh/sw stores (sizes 1/2/4). An access whose address is not a multiple of its size yields 'misaligned' (checked first); one extending past memory yields 'fault'. Data is little-endian. lb/lh/lw sign-extend from their top bit, lbu/lhu zero-extend. Stores write the low size bytes of value and yield None. Return [results, final memory].

Why this case matters

Memory access emulation must reproduce endianness, extension and alignment traps bit-exactly.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
store then load back	`[[null, -320017172, 236, null, 23130], [131, 127, 254, 255, 1, 128, 52, 18, 236, 236, 90, 90]]`	`[[null, -1985229332, 205, null, 23130], [131, 127, 254, 255, 1, 128, 52, 18, 236, 205, 90, 90]]`	Failed

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This record includes three runnable implementations, regression fixtures, execution results, and source hashes.

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