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Change mind about carry behaviour.

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This commit is contained in:
Thomas Harte 2024-04-01 21:38:44 -04:00
parent 7de92a9457
commit 7c9715f00c
1 changed files with 1 additions and 6 deletions
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7
InstructionSets/ARM/Executor.hpp
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@ -120,13 +120,8 @@ struct Executor {
operand2 = fields.immediate(); operand2 = fields.immediate();
if(fields.rotate()) { if(fields.rotate()) {
shift<ShiftType::RotateRight, shift_sets_carry>(operand2, fields.rotate(), rotate_carry); shift<ShiftType::RotateRight, shift_sets_carry>(operand2, fields.rotate(), rotate_carry);
} else {
// This is possibly clarified by later data sheets; take carry as if a rotate by 32
// had occurred.
if constexpr (shift_sets_carry) {
rotate_carry = operand2 & 0x8000'0000;
}
} }
// Complete guess: carry is unaffected by an immediate value that doesn't rotate.
} else { } else {
operand2 = decode_shift<true, shift_sets_carry>(fields, rotate_carry, shift_by_register ? 8 : 4); operand2 = decode_shift<true, shift_sets_carry>(fields, rotate_carry, shift_by_register ? 8 : 4);
} }