Start work on floating point library for calculator.asm
This commit is contained in:
Juhani Krekelä
parent
bafaef9c44
commit
37f487ae3f
561
calculator.asm
561
calculator.asm
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@ -1,5 +1,18 @@
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org 0
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cleq r0, r0, normalize
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load r0, fResultPtr+0
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load r1, fResultPtr+1
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cleq r0, r0, pushWord
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cleq r0, r0, fPack
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cleq r0, r0, fPrint
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cleq r0, r0, newline
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halt
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cleq r0, r0, readline
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load r0, linelen+0
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@ -227,6 +240,467 @@ readline:
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store ffff, r3
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breq r0, r0, readlineLoop
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; ==================================================================
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; Floating point
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; ==================================================================
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; ------------------------------------------------------------------
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; Format conversion
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; ------------------------------------------------------------------
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; When on-stack, a floating point number uses an 8-byte packed BCD format
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; 0 1 2 3 4 5 6 7
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; seee mmmm mmmm mmmm
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; |\_/ \____________/
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; | | |
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; | | mantissa, first digit being before and rest after the point
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; | exponent, with a bias of 500 (i.e. value of 0 means ×10⁻⁵⁰⁰)
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; sign, 00 for non-negative, 01 for negative, 02 for overflow
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; For operation, the format is instead an 18-byte unpacked BCD format
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; 0 1 2 3 4 5 6 7 8 9 a b c d e f 10 11
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; 0s 0e 0e 0e 0o 0m 0m 0m 0m 0m 0m 0m 0m 0m 0m 0m 0m 0r
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; | \______/ | \_________________________________/ |
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; | | | | extra digit for rounding
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; | | | mantissa
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; | | extra digit for overflow
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; | exponent
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; sign
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; f ptr --
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fUnpack:
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; Start from the end
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xor r0, r0
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load r1, #11
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cleq r0, r0, pushWord
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cleq r0, r0, stAdd
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; Zero out rounding digit
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xor r0, r0
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xor r1, r1
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cleq r0, r0, pushWord
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cleq r0, r0, stOver
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cleq r0, r0, stStoreByte
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cleq r0, r0, stDec
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; Mantissa
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cleq r0, r0, fUnpackWord
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cleq r0, r0, fUnpackWord
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cleq r0, r0, fUnpackWord
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; Zero out overflow digit
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xor r0, r0
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xor r1, r1
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cleq r0, r0, pushWord
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cleq r0, r0, stOver
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cleq r0, r0, stStoreByte
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cleq r0, r0, stDec
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; Sign and exponent
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cleq r0, r0, fUnpackWord
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; Clear off the pointer from the stack
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breq r0, r0, popWord
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; w ptr -- ptr-4
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fUnpackWord:
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; Low nybble of low byte
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cleq r0, r0, stOver
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cleq r0, r0, stLowNybble
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cleq r0, r0, stOver
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cleq r0, r0, stStoreByte
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cleq r0, r0, stDec
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; High nybble of low byte
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cleq r0, r0, stOver
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cleq r0, r0, stShr4
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cleq r0, r0, stLowNybble
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cleq r0, r0, stOver
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cleq r0, r0, stStoreByte
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cleq r0, r0, stDec
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; Low nybble of high byte
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cleq r0, r0, stOver
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cleq r0, r0, stShr8
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cleq r0, r0, stLowNybble
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cleq r0, r0, stOver
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cleq r0, r0, stStoreByte
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cleq r0, r0, stDec
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; High nybble of high byte
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cleq r0, r0, stSwap ; Clear off the word from the stack
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cleq r0, r0, stShr8
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cleq r0, r0, stShr4
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cleq r0, r0, stLowNybble
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cleq r0, r0, stOver
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cleq r0, r0, stStoreByte
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cleq r0, r0, stDec
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ret
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; ptr -- f
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fPack:
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; Sign and exponent
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cleq r0, r0, fPackWord
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; Skip over the overflow digit
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cleq r0, r0, stInc
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; Mantissa
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cleq r0, r0, fPackWord
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cleq r0, r0, fPackWord
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cleq r0, r0, fPackWord
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; Clean off the pointer from stack
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breq r0, r0, popWord
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; ptr -- w ptr+4
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fPackWord:
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; High nybble of high byte
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cleq r0, r0, stDup
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cleq r0, r0, stLoadByte
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cleq r0, r0, stShl8
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cleq r0, r0, stShl4
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cleq r0, r0, stSwap
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cleq r0, r0, stInc
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cleq r0, r0, stSwap
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; Low nybble of high byte
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cleq r0, r0, stOver
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cleq r0, r0, stLoadByte
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cleq r0, r0, stShl8
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cleq r0, r0, stOr
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cleq r0, r0, stSwap
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cleq r0, r0, stInc
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cleq r0, r0, stSwap
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; High nybble of low byte
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cleq r0, r0, stOver
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cleq r0, r0, stLoadByte
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cleq r0, r0, stShl4
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cleq r0, r0, stOr
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cleq r0, r0, stSwap
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cleq r0, r0, stInc
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cleq r0, r0, stSwap
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; Low nybble of low byte
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cleq r0, r0, stOver
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cleq r0, r0, stLoadByte
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cleq r0, r0, stOr
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cleq r0, r0, stSwap
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cleq r0, r0, stInc
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ret
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; ------------------------------------------------------------------
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; Unpacked floating point variables
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; ------------------------------------------------------------------
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fArg1Ptr: addr fArg1
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fArg1:
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data 00 ; sign
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data 00 ; exponent
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data 00
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data 00
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data 00 ; overflow
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data 00 ; mantissa
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data 00
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data 00
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data 00
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data 00
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data 00
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data 00
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data 00
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data 00
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data 00
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data 00
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data 00
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data 00 ; rounding
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fResultPtr: addr fResult
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fResult:
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data 01 ; sign
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data 04 ; exponent
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data 09
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data 09
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data 00 ; overflow
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data 01 ; mantissa
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data 00
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data 00
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data 00
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data 00
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data 00
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data 00
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data 00
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data 00
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data 00
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data 00
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data 01
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data 00 ; rounding
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; ------------------------------------------------------------------
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; Arithmetic
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; ------------------------------------------------------------------
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; x y -- tens(x+y) ones(x+y)
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bcdDigitAdd:
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cleq r0, r0, stAdd
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cleq r0, r0, stDup
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xor r0, r0
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load r1, #a
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cleq r0, r0, pushWord
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cleq r0, r0, stGtEq
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breq r0, r1, bcdDigitAddNoAdjust
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; Adjust so that carry is in the high nybble
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; Basically we want 9+1=a₁₆ to become 10₁₆
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xor r0, r0
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load r1, #6
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cleq r0, r0, pushWord
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cleq r0, r0, stAdd
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bcdDigitAddNoAdjust:
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cleq r0, r0, stDup
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cleq r0, r0, stShr4
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cleq r0, r0, stSwap
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breq r0, r0, stLowNybble
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; x -- 9-x
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bcdDigit9sComplement:
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xor r0, r0
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load r1, #9
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cleq r0, r0, pushWord
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cleq r0, r0, stSwap
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breq r0, r0, stSub
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; --
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normalize:
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; Is extended mantissa all zeroes?
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load r0, fResult+4
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load r1, fResult+5
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or r0, r1
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load r1, fResult+6
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or r0, r1
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load r1, fResult+7
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or r0, r1
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load r1, fResult+8
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or r0, r1
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load r1, fResult+9
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or r0, r1
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load r1, fResult+a
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or r0, r1
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load r1, fResult+b
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or r0, r1
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load r1, fResult+c
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or r0, r1
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load r1, fResult+d
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or r0, r1
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load r1, fResult+e
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or r0, r1
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load r1, fResult+f
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or r0, r1
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load r1, fResult+10
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or r0, r1
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load r1, fResult+11
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or r0, r1
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xor r1, r1
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breq r0, r1, normalizeZero
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; XXX: Implement rest
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ret
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normalizeZero:
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; Zero out the entire number
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; This causes sign to be 0 (non-negative), exponent -500, and
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; extended mantissa 00.000000000000
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load r0, fResultPtr+0
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load r1, fResultPtr+1
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cleq r0, r0, pushWord
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xor r0, r0
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load r1, #12
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cleq r0, r0, pushWord
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breq r0, r0, stZeroMem
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; ------------------------------------------------------------------
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; Output
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; ------------------------------------------------------------------
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fPrint:
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load r0, fArg1Ptr+0
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load r1, fArg1Ptr+1
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cleq r0, r0, pushWord
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cleq r0, r0, fUnpack
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; Overflow?
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load r0, fArg1+0
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load r1, #2
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breq r0, r1, fPrintOverflow
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; Negative?
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load r1, #1
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brneq r0, r1, fPrintMantissa
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load r0, #2d ; -
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store ffff, r0
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fPrintMantissa:
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load r0, fArg1+5
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cleq r0, r0, writehexNybble
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load r0, #2e ; .
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store ffff, r0
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load r0, fArg1+6
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cleq r0, r0, writehexNybble
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load r0, fArg1+7
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cleq r0, r0, writehexNybble
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load r0, fArg1+8
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cleq r0, r0, writehexNybble
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load r0, fArg1+9
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cleq r0, r0, writehexNybble
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load r0, fArg1+a
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cleq r0, r0, writehexNybble
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load r0, fArg1+b
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cleq r0, r0, writehexNybble
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load r0, fArg1+c
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cleq r0, r0, writehexNybble
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load r0, fArg1+d
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cleq r0, r0, writehexNybble
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load r0, fArg1+e
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cleq r0, r0, writehexNybble
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load r0, fArg1+f
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cleq r0, r0, writehexNybble
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load r0, fArg1+10
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cleq r0, r0, writehexNybble
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fPrintExponent:
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load r0, #65 ; e
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store ffff, r0
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; Adjust the hundreds digit for the bias
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xor r0, r0,
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load r1, fArg1+1
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cleq r0, r0, pushWord
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xor r0, r0
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load r1, #5
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cleq r0, r0, pushWord
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cleq r0, r0, bcdDigitAdd
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; Is the exponent negative?
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cleq r0, r0, stSwap
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cleq r0, r0, popWord
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breq r0, r1, fPrintNegativeExponent
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cleq r0, r0, popWord
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xor r0, r0
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or r0, r1
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cleq r0, r0, writehexNybble
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load r0, fArg1+2
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cleq r0, r0, writehexNybble
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load r0, fArg1+3
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cleq r0, r0, writehexNybble
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ret
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fPrintNegativeExponent:
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cleq r0, r0, popWord ; Remove result we don't need
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load r0, #2d ; -
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store ffff, r0
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; The exponent is stored with a bias of 500
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; unbiased + 500 = biased
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; By this point we know unbiased < 0 and have printed the minus
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; sign, so we want to print the negative of unbiased
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; unbiased + 500 = biased
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; unbiased = -500 + biased
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; -unbiased = 500 - biased
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; We implement subtraction using 9's complement, where each
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; digit of the subtrahend is subtracted from 9 before being
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; added to the corresponding minuend. This by itself gives a
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; result that is one too small, so we add one to it (c.f. binary
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; subtraction, where we negate the subtrahend and then add one).
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; Normally we'd have to split subtraction into two rounds, one
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; to add the complemented subtrahend and one to add the 1, but
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; since our minuend is a constant, we can add 1 to it instead.
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; 501 + 999 - biased
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; = 500 + 1 + 999 - biased
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; = 500 + 1000 - biased (1000 = 0 mod 1000)
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; = 500 - biased
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; Ones
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xor r0, r0
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load r1, #1
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cleq r0, r0, pushWord
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xor r0, r0
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load r1, fArg1+3
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cleq r0, r0, pushWord
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cleq r0, r0, bcdDigit9sComplement
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cleq r0, r0, bcdDigitAdd
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cleq r0, r0, stSwap
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; Tens
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xor r0, r0
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load r1, fArg1+2
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cleq r0, r0, pushWord
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cleq r0, r0, bcdDigit9sComplement
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cleq r0, r0, bcdDigitAdd
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cleq r0, r0, stSwap
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; Hundreds
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xor r0, r0
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load r1, #5
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cleq r0, r0, pushWord
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cleq r0, r0, bcdDigitAdd
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cleq r0, r0, stSwap
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cleq r0, r0, popWord
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xor r0, r0
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load r1, fArg1+1
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cleq r0, r0, pushWord
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cleq r0, r0, bcdDigit9sComplement
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cleq r0, r0, bcdDigitAdd
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cleq r0, r0, stSwap
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cleq r0, r0, popWord
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; Print
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cleq r0, r0, popWord
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xor r0, r0
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or r0, r1
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cleq r0, r0, writehexNybble
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cleq r0, r0, popWord
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xor r0, r0
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or r0, r1
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cleq r0, r0, writehexNybble
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cleq r0, r0, popWord
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xor r0, r0
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or r0, r1
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cleq r0, r0, writehexNybble
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ret
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fPrintOverflow:
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load r0, #4f ; O
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store ffff, r0
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load r0, #76 ; v
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store ffff, r0
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load r0, #65 ; e
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store ffff, r0
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load r0, #72 ; r
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store ffff, r0
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load r0, #66 ; f
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store ffff, r0
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load r0, #6c ; l
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store ffff, r0
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load r0, #6f ; o
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store ffff, r0
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load r0, #77 ; w
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store ffff, r0
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ret
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; ==================================================================
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; Stack-based functions
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; ==================================================================
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@ -265,6 +739,62 @@ stDec:
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cleq r0, r0, decWord
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breq r0, r0, pushWord
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; a b -- a|b
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stOr:
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cleq r0, r0, popWord
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cleq r0, r0, tmpStoreWord01
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cleq r0, r0, popWord
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cleq r0, r0, tmpLoadWord23
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or r0, r2
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or r1, r3
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breq r0, r0, pushWord
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; a -- a<<8
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stShl8:
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cleq r0, r0, popWord
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xor r0, r0
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or r0, r1
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xor r1, r1
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breq r0, r0, pushWord
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; a -- a>>8
|
||||
stShr8:
|
||||
cleq r0, r0, popWord
|
||||
xor r1, r1
|
||||
or r1, r0
|
||||
xor r0, r0
|
||||
breq r0, r0, pushWord
|
||||
|
||||
; a -- a<<4
|
||||
stShl4:
|
||||
cleq r0, r0, popWord
|
||||
shl r0, 4
|
||||
xor r2, r2
|
||||
or r2, r1
|
||||
shr r2, 4
|
||||
or r0, r2
|
||||
shl r1, 4
|
||||
breq r0, r0, pushWord
|
||||
|
||||
; a -- a>>4
|
||||
stShr4:
|
||||
cleq r0, r0, popWord
|
||||
shr r1, 4
|
||||
xor r2, r2
|
||||
or r2, r0
|
||||
shl r2, 4
|
||||
or r1, r2
|
||||
shr r0, 4
|
||||
breq r0, r0, pushWord
|
||||
|
||||
; a -- a&f
|
||||
stLowNybble:
|
||||
cleq r0, r0, popWord
|
||||
xor r0, r0
|
||||
load r2, #f
|
||||
and r1, r2
|
||||
breq r0, r0, pushWord
|
||||
|
||||
; a b --
|
||||
; if a >= b then r0:r1 = 0001
|
||||
; else r0:r1 = 0000
|
||||
|
|
@ -393,6 +923,28 @@ stLoadWord:
|
|||
or r1, r2
|
||||
breq r0, r0, pushWord
|
||||
|
||||
; ptr n --
|
||||
stZeroMem:
|
||||
cleq r0, r0, peekWord
|
||||
or r0, r1
|
||||
xor r2, r2
|
||||
breq r0, r2, stZeroMemDone
|
||||
|
||||
cleq r0, r0, stDec
|
||||
cleq r0, r0, stSwap
|
||||
cleq r0, r0, stDup
|
||||
xor r0, r0
|
||||
xor r1, r1
|
||||
cleq r0, r0, pushWord
|
||||
cleq r0, r0, stSwap
|
||||
cleq r0, r0, stStoreByte
|
||||
cleq r0, r0, stInc
|
||||
cleq r0, r0, stSwap
|
||||
breq r0, r0, stZeroMem
|
||||
|
||||
stZeroMemDone:
|
||||
ret
|
||||
|
||||
; ==================================================================
|
||||
; Low-level functions
|
||||
; ==================================================================
|
||||
|
|
@ -981,6 +1533,15 @@ writehexByte:
|
|||
|
||||
ret
|
||||
|
||||
; in:
|
||||
; r0 = nybble
|
||||
; clobbers:
|
||||
; r3
|
||||
writehexNybble:
|
||||
cleq r0, r0, nybble2hex
|
||||
store ffff, r0
|
||||
ret
|
||||
|
||||
; ------------------------------------------------------------------
|
||||
; Common output routines
|
||||
; ------------------------------------------------------------------
|
||||
|
|
|
|||
Loading…
Reference in New Issue