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wip: integer division approximation #126

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150 changes: 63 additions & 87 deletions source/common/aa.system/04data.inc
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Original file line number Diff line number Diff line change
@@ -1,27 +1,12 @@
; ************************************************************************************************
; ************************************************************************************************
;
; Name: 04data.inc
; Purpose: Main Data
; Created: 18th September 2022
; Reviewed: 23rd November 2022
; Author: Paul Robson (paul@robsons.org.uk)
;
; ************************************************************************************************
; ************************************************************************************************

; ************************************************************************************************
;
; Mandatory Zero page code
;
; ************************************************************************************************
; Mandatory zero-page data

.section zeropage

codePtr: ; address of current line (allow for 32 bit)
.fill 4
basicStack: ; BASIC stack address
.fill 2
.fill 2
zTemp0: ; temporary words used in the interpreter.
.fill 2
zTemp1:
Expand All @@ -32,61 +17,68 @@ zsTemp: ; allocated string temporary.
.fill 2
zaTemp: ; allocated array temporary
.fill 2

safePtr = codePtr ; minimise direct tinkering

.send zeropage

; ************************************************************************************************
;
; Preferable Zero page code
;
; ************************************************************************************************
.send zeropage

NSBIsNegative = $80 ; bit 7 : sign of mantissa (where numeric)
NSBIsReference = $20 ; bit 5 : is a reference
NSBIsString = $10 ; bit 4 : set if string (procedures don't go on the stack)
NSBTypeMask = $18 ; bits 4,3 : 00 int 01 float 10 string 11 procedure
NSBRefMask = $03 ; bits 0,1 : Bytes of reference, 00 = 4,01 = 1,10=2
NSBIsArray = $04

NSTInteger = $00 ; base types for bits 3..4
NSTFloat = $08
NSTString = $10
NSTProcedure = $18
; Preferably zero-page data

.section zeropref

; ************************************************************************************************
;
; The number stack (works up from zero)
;
; ************************************************************************************************
; Number stack status masks

NSBIsNegative = $80 ; bit 7: sign of mantissa (where numeric)
NSBIsReference = $20 ; bit 5: is a reference
NSBIsString = $10 ; bit 4: set if string (procedures don't go on the stack)
NSBTypeMask = $18 ; bits 4,3: 00 int 01 float 10 string 11 procedure
NSBRefMask = $03 ; bits 0,1: Bytes of reference, 00 = 4,01 = 1,10=2
NSBIsArray = $04

NSTInteger = $00 ; base types for bits 3..4
NSTFloat = $08
NSTString = $10
NSTProcedure = $18

;;
; The number stack (works up from zero)
;;
NSStatus: ; Status bits of stack.
.fill MathStackSize
NSMantissa0: ; Mantissa on stack (address in 0,1 for string/reference)
.fill MathStackSize ; (this is my integer mantissa system)
NSMantissa1: ; the order of the mantissa elements is required.

; 4 mantissa bytes (little-endian, 31 bits + sign)
;
; Stores an integer magnitude. Normalized non-zero mantissa always has bit 30 set.
;
; Note that on the number stack, the sign is kept in `NSStatus` (`NSBIsNegative` mask), so the
; mantissa itself only carries magnitude; when a float is written out to a variable, the sign
; bit gets packed into the top bit of the highest mantissa byte.
NSMantissa0:
.fill MathStackSize
NSMantissa1:
.fill MathStackSize
NSMantissa2:
.fill MathStackSize
NSMantissa3:
.fill MathStackSize
NSExponent: ; Exponent , 0 = Mantissa is integer


; a signed 8-bit base-2 exponent stored in two's complement format; 0 if mantissa is integer
;
; floating-point value = mantissa x 2^decoded exponent, where
; decoded exponent = exponent if exponent < 128 else exponent - 256
NSExponent:
.fill MathStackSize

fnStackLevel: ; saved stack level for function evaluation
; saved stack level for function evaluation
fnStackLevel:
.fill 1

.send zeropref


; ************************************************************************************************
;
; Non Zero Page Data
;
; ************************************************************************************************
; Non-zero page data

.section storage

Expand All @@ -95,7 +87,7 @@ identStart: ; start of identifier in line buffer
identTypeStart: ; start of type information (#$ and ( in the line buffer)
.fill 1
identTypeEnd: ; character after end of type information in the line buffer
.fill 1
.fill 1
identHash: ; hash of identifier (including the type characters)
.fill 1
identTypeByte: ; type descriptor in format used in identifier record
Expand All @@ -113,63 +105,63 @@ lowMemPtr: ; memory allocation after program.
arrayMemPtr: ; array/alloc storage pointer (slots 2-3, $4000-$7FFF)
.fill 2
stringMemory: ; allocate concrete strings from here
.fill 2
stringInitialised: ; string
.fill 1
.fill 2
stringInitialised: ; string
.fill 1
stringTempPointer: ; temporary string
.fill 2
.fill 2

breakCheck: ; break check counter/shift
.fill 1

decimalPlaces: ; no of decimals.
.fill 1
dbOffset: ; offset into decimal buffer.
.fill 1
.fill 1

lastParameter: ; final stack offset when all parameters handled.
.fill 1

dataPointer: ; operates like code pointer for DATA statements
.fill 5
inDataStatement: ; non zero when in data statement, e.g. pointing to data
.fill 1
.fill 1

tbOffset: ; offset into token buffer
.fill 1
.fill 1

AssemblerAddress: ; address being assembled at
.fill 2
AssemblerControl: ; assembler control byte - bit 0 (errors ok), bit 1 (listing on)
.fill 1
.fill 1
ParamStart: ; offset of parameter.
.fill 2
.fill 2
IsGroup1: ; flag set if group.1
.fill 1
.fill 1
BaseOpcode: ; base opcode
.fill 1
.fill 1
ModeMask: ; modes allowed
.fill 1
.fill 1
listIndent: ; list indent level.
.fill 1
listElseFound: ; flag set when ELSE found on line (for indent fix)
.fill 1
listEndToken: ; closing token for LIST proc/fn
.fill 1
lcLastCharacter: ; last character output.
.fill 1
.fill 1
isPrintFlag: ; zero if input, non-zero if print, bit 6 zero = character print
.fill 1
.fill 1
currentListColour: ; current set colour when listing.
.fill 1
;
; New tokenised line - these three *must* be contiguous as they are used as a single entity
;
;
tokenOffset: ; used for tokenising - tokenised result goes here
.fill 1
.fill 1
tokenLineNumber:
.fill 2
tokenBuffer:
.fill 2
tokenBuffer:
.fill 253

lineBuffer: ; used for input - ASCII line goes here
Expand All @@ -193,19 +185,3 @@ decimalBuffer: ; buffer for number -> string conversion.
.fill 24

.send storage

; ************************************************************************************************
;
; Changes and Updates
;
; ************************************************************************************************
;
; Date Notes
; ==== =====
; 1/12/2022 Changed the recorded values used in the reference byte size which were
; incorrect, no code change.
; 2/12/2022 Made line buffer long again, as long lines can be entered via cross
; development which would crash the interpreter.
;
; ************************************************************************************************

70 changes: 28 additions & 42 deletions source/common/expressions/float/integer.asm
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Original file line number Diff line number Diff line change
@@ -1,60 +1,46 @@
; ************************************************************************************************
; ************************************************************************************************
;
; Name: integer.asm
; Purpose: Make FPA Denormalised integer
; Created: 29th September 2022
; Reviewed: 28th November 2022
; Author : Paul Robson (paul@robsons.org.uk)
;
; ************************************************************************************************
; ************************************************************************************************

.section code

; ************************************************************************************************
;;
; Convert floating-point entry at position X in the number stack to an
; integer.
;
; Make FPA into an integer
;
; ************************************************************************************************

; Sets carry if the value was not already an exact integer.
;;
FloatIntegerPart:
pha
;
phy
ldy #$0 ; store the carry status in Y

lda NSExponent,x ; is it integer already ?
beq _FIPExit ; if so do nothing
beq _exit ; if so do nothing
jsr NSMIsZero ; is it zero ?
beq _FIPZero ; if so return zero.
;
beq _zero ; if so return zero.

jsr NSNormalise ; normalise
beq _FIPZero ; normalised to zero, exit zero
;
_FIPShift:
beq _zero ; normalised to zero, exit zero

_shift:
lda NSExponent,x ; if Exponent >= 0 exit.
bpl _FIPCheckZero
bpl _check_zero

jsr NSMShiftRight ; shift mantissa right
inc NSExponent,x ; bump exponent
bra _FIPShift
bcc +
ldy #$1 ; record that we lost a non-zero bit
+ inc NSExponent,x ; bump exponent
bra _shift

_FIPCheckZero:
_check_zero:
jsr NSMIsZero ; avoid -0 problem
bne _FIPExit ; set to zero if mantissa zero.
_FIPZero:
bne _exit ; set to zero if mantissa zero.

_zero:
jsr NSMSetZero
_FIPExit:

_exit:
cpy #$1 ; sets the carry flag if Y is 1
ply
pla
rts
rts

.send code

; ************************************************************************************************
;
; Changes and Updates
;
; ************************************************************************************************
;
; Date Notes
; ==== =====
;
; ************************************************************************************************
19 changes: 10 additions & 9 deletions source/common/expressions/float/utility.asm
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Original file line number Diff line number Diff line change
Expand Up @@ -28,19 +28,20 @@ FloatPrepare:
_FDType:
jmp TypeError

; ************************************************************************************************
;
; Normalise Stack[X]

;;
; Normalize floating-point entry at position X in the number stack.
;
; ************************************************************************************************
; \in X Index of the entry in the number stack.
;;

NSNormalise:
lda NSStatus,x ; make float, keep sign
and #$80
ora #NSTFloat
ora #NSTFloat
sta NSStatus,x

jsr NSMIsZero ; if zero exit
jsr NSMIsZero ; if zero exit
bne _NSNormaliseOptimise ; if so, normalise it.
asl NSStatus,x ; clear the sign bit.
ror NSStatus,x ; (no -0)
Expand All @@ -50,7 +51,7 @@ NSNormalise:
; Normalise by byte if the MSB is zero we can normalise it
; (providing bit 7 of 2nd byte is not set)
;
_NSNormaliseOptimise:
_NSNormaliseOptimise:
lda NSMantissa3,x ; upper byte zero ?
bne _NSNormaliseLoop
lda NSMantissa2,x ; byte normalise
Expand All @@ -71,7 +72,7 @@ _NSNormaliseOptimise:
;
; Normalise by bit
;
_NSNormaliseLoop:
_NSNormaliseLoop:
bit NSMantissa3,x ; bit 30 set ?
bvs _NSNExit ; exit if so with Z flag clear
jsr NSMShiftLeft ; shift mantissa left
Expand All @@ -82,7 +83,7 @@ _NSNExit:
rts

.send code

; ************************************************************************************************
;
; Changes and Updates
Expand Down
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