Anachronaut
e1273337c4
Twenty four places moved Q into A or B by pushing it and popping it back. That is four bus cycles and two bytes to do what MVQA does in one of each, and several of them are inside loops - Life, the calculator, int8. Nineteen more loaded zero with INIA 0d0 where RSTA says the same thing in one byte. Both are equivalent at the CPU rather than by assertion: RSTA and INIA both leave Status alone, and PSHQ followed by POPA nets to A = Q with the Stack Pointer where it started. The one difference is that the pair leaves a copy of Q in memory just below the Stack Pointer and MVQA does not, which nothing here reads. Five recorded outputs moved and every one of them says the change worked: - 16x16Life fits five more generations into the same cycle budget, the first 457 lines identical, because the loop got cheaper. - Life.sbx is 1409 bytes rather than 1411, in three tests that list it. - Edit.sbx is 1995 rather than 1996. That last one broke a check I added this morning, and the hole is worth recording: the CosmOS README's claim about Edit's size did not have the word "Edit" on the same line as the number, because the subject was in the sentence before, so the check that measures quoted sizes skipped it silently. The sentence now names what it is talking about, which makes it both checkable and clearer, and the check fails on a wrong number there. Comments on either half of a replaced pair are carried onto the instruction that replaces them, so nothing anybody wrote was lost.
401 lines
4.4 KiB
NASM
401 lines
4.4 KiB
NASM
; Interactive hexadecimal calculator for SplitBit.
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;
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; Enter expressions as:
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; HH operator HH
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; Whitespace is optional. Supported operators are + - * & | and ^.
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; Arithmetic wraps to eight bits. Enter Q to quit.
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#Include print.asm
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#Program
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start:
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SETD Welcome
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CALL printString
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repl:
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SETD Prompt
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CALL printString
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CALL readNonSpace
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MVQA
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; Q, q, or end-of-file exits.
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INIB 0xFF
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XOR
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BRQ quit
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INIB 0x51
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XOR
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BRQ quit
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INIB 0x71
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XOR
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BRQ quit
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CALL readHexByteFirst
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SETD LeftOperand
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STQ
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CALL parseIsInvalid
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BRQ inputError
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CALL readNonSpace
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MVQA
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SETD Operator
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STA
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CALL readNonSpace
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MVQA
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CALL readHexByteFirst
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SETD RightOperand
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STQ
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CALL parseIsInvalid
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BRQ inputError
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CALL discardLine
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CALL evaluate
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SETD Result
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STQ
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CALL operatorIsInvalid
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BRQ operatorError
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SETD Result
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LDA
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CALL printByteHex
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CALL lineFeed
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BRI repl
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inputError:
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CALL discardLine
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SETD BadInput
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CALL printString
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BRI repl
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operatorError:
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SETD BadOperator
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CALL printString
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BRI repl
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quit:
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SETD Goodbye
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CALL printString
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HALT
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; Read a character other than space, tab, CR, or LF. Return it in Q.
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readNonSpace:
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readNonSpaceLoop:
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INA 0x00
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INIB 0x20
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XOR
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BRQ readNonSpaceLoop
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INIB 0x09
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XOR
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BRQ readNonSpaceLoop
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INIB 0x0A
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XOR
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BRQ readNonSpaceLoop
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INIB 0x0D
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XOR
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BRQ readNonSpaceLoop
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RSTB
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CCF
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ADD
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RET
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; A contains the first hexadecimal digit. Read the second and return the byte
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; in Q. Q is 0xFF on malformed input.
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readHexByteFirst:
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CALL clearParseStatus
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CALL hexNibble
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MVQA
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INIB 0xFF
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XOR
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BRQ invalidByte
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RSTB
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SHL
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SHL
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SHL
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SHL
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PSHA
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CALL readNonSpace
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MVQA
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CALL hexNibble
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MVQA
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INIB 0xFF
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XOR
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BRQ invalidLowNibble
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POPB
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OR
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RET
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invalidLowNibble:
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POPB
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invalidByte:
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PSHD
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SETD ParseStatus
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INIA 0x01
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STA
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POPD
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INIA 0xFF
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RSTB
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CCF
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ADD
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RET
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; Convert the ASCII hexadecimal digit in A to a value in Q.
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; Uppercase and lowercase letters are accepted. Q=0xFF means invalid.
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hexNibble:
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PSHA
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; Try 0 through 9.
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INIB 0x30
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CCF
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SUB
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BRC tryUpperHex
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MVQA
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INIB 0d10
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CCF
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SUB
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BRC decimalNibble
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tryUpperHex:
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POPA
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PSHA
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INIB 0x41
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CCF
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SUB
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BRC tryLowerHex
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MVQA
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INIB 0d06
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CCF
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SUB
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BRC upperNibble
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tryLowerHex:
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POPA
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PSHA
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INIB 0x61
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CCF
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SUB
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BRC badNibble
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MVQA
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INIB 0d06
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CCF
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SUB
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BRC lowerNibble
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badNibble:
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POPA
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INIA 0xFF
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RSTB
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CCF
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ADD
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RET
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decimalNibble:
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POPB
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RSTB
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CCF
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ADD
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RET
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upperNibble:
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POPB
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INIB 0d10
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CCF
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ADD
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RET
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lowerNibble:
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POPB
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INIB 0d10
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CCF
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ADD
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RET
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; Return Q=0 if Q was 0xFF, otherwise return a nonzero value.
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resultIsInvalid:
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MVQA
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INIB 0xFF
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XOR
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RET
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clearParseStatus:
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PSHD
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SETD ParseStatus
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RSTA
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STA
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POPD
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RET
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parseIsInvalid:
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PSHD
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SETD ParseStatus
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LDA
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INIB 0x01
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XOR
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POPD
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RET
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operatorIsInvalid:
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PSHD
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SETD OperatorStatus
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LDA
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INIB 0x01
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XOR
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POPD
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RET
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; Evaluate the stored expression and return its result in Q.
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evaluate:
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PSHD
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SETD OperatorStatus
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RSTA
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STA
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POPD
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SETD Operator
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LDA
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INIB 0x2B
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XOR
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BRQ evaluateAdd
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INIB 0x2D
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XOR
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BRQ evaluateSubtract
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INIB 0x2A
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XOR
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BRQ evaluateMultiply
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INIB 0x26
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XOR
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BRQ evaluateAnd
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INIB 0x7C
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XOR
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BRQ evaluateOr
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INIB 0x5E
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XOR
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BRQ evaluateXor
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SETD OperatorStatus
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INIA 0x01
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STA
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RSTA
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RSTB
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CCF
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ADD
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RET
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evaluateAdd:
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SETD LeftOperand
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LDA
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INCD
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LDB
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CCF
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ADD
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RET
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evaluateSubtract:
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SETD LeftOperand
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LDA
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INCD
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LDB
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CCF
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SUB
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RET
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evaluateAnd:
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SETD LeftOperand
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LDA
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INCD
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LDB
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AND
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RET
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evaluateOr:
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SETD LeftOperand
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LDA
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INCD
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LDB
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OR
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RET
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evaluateXor:
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SETD LeftOperand
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LDA
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INCD
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LDB
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XOR
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RET
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evaluateMultiply:
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RSTA
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SETD Product
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STA
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multiplyLoop:
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SETD RightOperand
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LDA
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BRA multiplyDone
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DECA
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STA
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SETD Product
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LDA
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SETD LeftOperand
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LDB
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CCF
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ADD
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SETD Product
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STQ
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BRI multiplyLoop
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multiplyDone:
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SETD Product
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LDA
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RSTB
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CCF
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ADD
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RET
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; Consume the rest of the current input line.
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discardLine:
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discardLoop:
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INA 0x00
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INIB 0x0A
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XOR
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BRQ discardDone
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INIB 0xFF
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XOR
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BRQ discardDone
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BRI discardLoop
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discardDone:
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RET
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#Data
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LeftOperand:
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0x00
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RightOperand:
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0x00
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Operator:
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0x00
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Product:
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0x00
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Result:
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0x00
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ParseStatus:
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0x00
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OperatorStatus:
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0x00
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Welcome:
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"SplitBit calculator (+ - * & | ^), Q quits."
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Prompt:
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0x0A
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"> "
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BadInput:
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"Invalid hexadecimal input."
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BadOperator:
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"Unknown operator."
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Goodbye:
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"Goodbye!"
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0x0A
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