URL https://opencores.org/ocsvn/ft816float/ft816float/trunk

Subversion Repositories ft816float

[/] [ft816float/] [trunk/] [software/] [FAC1ToString.asm] - Blame information for rev 60

Go to most recent revision | Details | Compare with Previous | View Log


; ============================================================================
; FAC1ToString.asm
;        __
;   \\__/ o\    (C) 2014  Robert Finch, Stratford
;    \  __ /    All rights reserved.
;     \/_//     robfinch@finitron.ca
;       ||
;
;
; This source file is free software: you can redistribute it and/or modify
; it under the terms of the GNU Lesser General Public License as published
; by the Free Software Foundation, either version 3 of the License, or
; (at your option) any later version.
;
; This source file is distributed in the hope that it will be useful,
; but WITHOUT ANY WARRANTY; without even the implied warranty of
; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
; GNU General Public License for more details.
;
; You should have received a copy of the GNU General Public License
; along with this program.  If not, see .
;
; ============================================================================
;
; This code is a heavily modified version of the floating point to string
; conversion routine which is a part of Lee Davison's EhBASIC.
;
Cvaral          = $95           ; current var address low byte
Cvarah          = Cvaral+1      ; current var address high byte
numexp          = $A8           ; string to float number exponent count
expcnt          = $AA           ; string to float exponent count
Sendl                   = $BA   ; BASIC pointer temp low byte
Sendh                   = $BB   ; BASIC pointer temp low byte
 
Decss           = $3A0          ; number to decimal string start
Decssp1         = Decss+1       ; number to decimal string start
FP_ADD          EQU             1
FP_SUB          EQU             2
FP_MUL          EQU             3
FP_DIV          EQU             4
FP_FIX2FLT      EQU             5
FP_FLT2FIX      EQU             6
FP_ABS          EQU             7
FP_NEG          EQU             16
FP_SWAP         EQU             17
FIXED_MUL       EQU             $83
FIXED_ADD       EQU             $81
FIXED_SUB       EQU             $82
;parameter FIXED_DIV = 8'h84;
;parameter FIXED_ABS = 8'h87;
;parameter FIXED_NEG = 8'h90;
FP_CMDREG       EQU             $FEA20E
FP_STATREG      EQU             $FEA20E
FAC1            EQU             $FEA200
FAC1_5          EQU             $FEA200
FAC1_4          EQU             $FEA202
FAC1_3          EQU             $FEA204
FAC1_2          EQU             $FEA206
FAC1_1          EQU             $FEA208
FAC1_msw        EQU             $FEA208
FAC1_e          EQU             $FEA20A
FAC2            EQU             $FEA210
 
        CPU             W65C816S
        NDX             16
        MEM             16
 
 
public FAC1ToString:
 
; The first chunk of code determines if the number is positive or negative
; and spits out the appropriate sign. Next it takes the absolute value of
; the accumulator so following code only has to deal with positive numbers.
 
        LDY     #$00                    ; set index = 1
        LDA     FAC1_msw                ; test FAC1 sign (b15) (Can't use BIT)
        BPL     .0002           ; branch if +ve
        LDA     #'-'                    ; else character = "-"
        STA     Decss,Y         ; save leading character (" " or "-")
        LDA     #FP_NEG         ; make the FAC positive
        JSR     FPCommandWait
        BRA     .0001
.0002:
        LDA     #$20                    ; character = " " (assume +ve)
        STA     Decss,Y
.0001:
        STY     Sendl                   ; save index
 
; This little bit of code check for a zero exponent which indicates a
; value of zero.
 
        LDA     FAC1_e          ; get FAC1 exponent
        TAX
        BNE     LAB_2989                ; branch if FAC1<>0
                                        ; exponent was $00 so FAC1 is 0
        LDA     #'0'                    ; set character = "0"
        BRL     LAB_2A89                ; save last character, [EOT] and exit
 
; This loop attempts to make small values more significant, so that there are
; fewer leading zeros in the value. (The exponent is decremented so that it
; corresponds). Because of the potential for extremely small values looping is
; limited. The problem is the 16 bit exponent can allow for much smaller
; values than an 8 bit exponent would and we don't want to loop for thousands
; of iterations in order to display a value that's almost zero.
 
                                        ; FAC1 is some non zero value
LAB_2989
        STY     Sendl                   ; save off .Y
        LDY #1639                       ; max number of retries
        LDA     #$00                    ; clear (number exponent count)
        STA numexp
LOOP_MBMILLION:
        CPX     #$8000                  ; compare FAC1 exponent with $8000 (>1.00000)
        BCS     LAB_299A                ; branch if FAC1=>1
                                        ; FAC1<1
        PEA     A_MILLION               ; multiply FAC * 1,000,000
        JSR     LOAD_FAC2               ;
        PLA                                     ; get rid of parameter
        JSR     FMUL
        LDA numexp
        SEC
        SBC     #6                              ; set number exponent count (-6)
        STA numexp
        LDA FAC1_e
        TAX
        DEY
        BPL     LOOP_MBMILLION
 
LAB_299A
        LDY     Sendl           ; get back .Y
 
; These two loops coerce the value of the FAC to be between 100,000 and
; 1,000,000. This gives a maximum of six digits before the decimal point
; in scientific notation.
 
; This loop divides by 10 until the value in the FAC is less than 1,000,000
;
LOOP_DB10:
        PEA     MAX_BEFORE_SCI  ; set pointer low byte to 999999.4375 (max before sci note)
        JSR     LOAD_FAC2               ; compare FAC1 with (AY)
        PLA                                     ; get rid of parameter
        LDA FP_CMDREG
        BIT     #$08                    ; test equals bit
        BNE     LAB_29C3                ; exit if FAC1 = (AY)
        BIT     #$04                    ; test greater than bit
        BEQ     LOOP_MB10               ; go do *10 if FAC1 < (AY)
 
LAB_29B9
        JSR     DivideByTen             ; divide by 10
        INC     numexp                  ; increment number exponent count
        BRA     LOOP_DB10               ; go test again (branch always)
 
; This loop multiplies the value by 10 until it's greater than
; 100,000.
                                        ; FAC1 < (AY)
LOOP_MB10
        PEA CONST_9375          ; set pointer to 99999.9375
        JSR     LOAD_FAC2               ; compare FAC1 with (AY)
        PLA                                     ; get rid of parameter
        LDA FP_CMDREG
        BIT #$08
        BNE     LAB_29B2                ; branch if FAC1 = (AY) (allow decimal places)
        BIT #$04
        BNE     LAB_29C0                ; branch if FAC1 > (AY) (no decimal places)
                                        ; FAC1 <= (AY)
LAB_29B2
        JSR     MultiplyByTen   ; multiply by 10
        DEC     numexp          ; decrement number exponent count
        BRA     LOOP_MB10               ; go test again (branch always)
 
; now we have just the digits to do
 
LAB_29C0
;       JSR     AddPoint5               ; add 0.5 to FAC1 (round FAC1)
LAB_29C3
;       JSR     FloatToFixed    ; convert FAC1 floating-to-fixed
        LDX     #$01                    ; set default digits before dp = 1
        LDA     numexp          ; get number exponent count
        CLC                             ; clear carry for add
        ADC     #$07                    ; up to 6 digits before point
        BMI     LAB_29D8                ; if -ve then 1 digit before dp
 
        CMP     #$08                    ; A>=8 if n>=1E6
        BCS     LAB_29D9                ; branch if >= $08
 
                                        ; carry is clear
        TAX                             ; copy to A
        DEX                             ; take 1 from digit count
        LDA     #$02                    ;.set exponent adjust
 
LAB_29D8
        SEC                             ; set carry for subtract
LAB_29D9
        SBC     #$02                    ; -2
        STA     expcnt          ;.save exponent adjust
        STX     numexp          ; save digits before dp count
        TXA                             ; copy to A
        BEQ     LAB_29E4                ; branch if no digits before dp
 
        BPL     LAB_29F7                ; branch if digits before dp
 
LAB_29E4
        LDY     Sendl                   ; get output string index
        LDA     #'.'                    ; character "."
        INY                             ; increment index
        STA     Decss,Y         ; save to output string
        TXA                             ;.
        BEQ     LAB_29F5                ;.
 
        LDA     #'0'                    ; character "0"
        INY                             ; increment index
        STA     Decss,Y         ; save to output string
LAB_29F5
        STY     Sendl                   ; save output string index
 
LAB_29F7
        LDX     #'0'                    ; holds onto the digit value
 
; Now loop subtracting 100,000 as many times as we can. The value was coerced
; to be between 100,000 and 1,000,000. Count the number of times subtraction
; can be done successfully.
;
LAB_29FB
        PEA CONST_100000
        JSR LOAD_FAC2   ; load FAC2 with 100,000
        PLA                             ; get rid of parameter
        LDA FP_STATREG
        BIT #$04                ; Is FAC1 > 100,000 ?
        BEQ     .0005           ; branch if not
        LDA #FP_SWAP    ; subtract is FAC2-FAC1!
        JSR FPCommandWait;
        LDA #FP_SUB             ; subtract 100,000 from the mantissa.
        JSR FPCommandWait
        INX                             ; increment the value of the digit
        BRA     LAB_29FB        ; try again
.0005:
        TXA
        LDY     Sendl                   ; get output string index
        INY                             ; increment output string index
        TXA
        STA     Decss,Y         ; save to output string
        DEC     numexp          ; decrement # of characters before the dp
        BNE     LAB_2A3B                ; branch if still characters to do
                                ; else output the point
        LDA     #'.'                    ; character "."
        INY                             ; increment output string index
        STA     Decss,Y         ; save to output string
LAB_2A3B
        STY     Sendl           ; save output string index
        ; We subtracted until the value was < 100,000 so multiply the
        ; remainder upwards to get the next digit.
        JSR     MultiplyByTen   ; If not, multiply by 10
        CPY #27                 ; converted (+/- . incl)
        BCC     LAB_29F7
                                        ; now remove trailing zeroes
.RemoveTrailingZeros
        LDA     Decss,Y         ; get character from output string
        AND     #$FF            ; mask to a byte
        DEY                             ; decrement output string index
        CMP     #'0'                    ; compare with "0"
        BEQ     .RemoveTrailingZeros    ; loop until non "0" character found
 
        CMP     #'.'                    ; compare with "."
        BEQ     LAB_2A58                ; branch if was dp
 
                                        ; restore last character
        INY                             ; increment output string index
LAB_2A58
        LDA     #'+'                    ; character "+"
        LDX     expcnt          ; get exponent count
        LBEQ    LAB_2A8C                ; if zero go set null terminator and exit
 
                                        ; exponent isn't zero so write exponent
        BPL     LAB_2A68                ; branch if exponent count +ve
 
        LDA     #$00                    ; clear A
        SEC                             ; set carry for subtract
        SBC     expcnt          ; subtract exponent count adjust (convert -ve to +ve)
        TAX                             ; copy exponent count to X
        LDA     #'-'                    ; character "-"
 
; We must keep moving forwards through the string because the acc is storing
; two bytes.
 
LAB_2A68
        PHA
        LDA     #'E'                    ; character "E"
        STA     Decss+1,Y               ; save exponent sign to output string
        PLA
        STA     Decss+2,Y               ; save to output string
        TXA                             ; get exponent count back
 
; do highest exponent digit
        STZ Sendl
        LDX     #'0'-1          ; one less than "0" character
        SEC                             ; set carry for subtract
.0001:
        INX                             ; count how many times we can subtract 10,000
        SBC     #10000
        BCS .0001
        ADC #10000
        CPX #'0'
        BEQ .0005
        INC Sendl
        PHA
        TXA
        STA Decss+3,Y
        PLA
        INY
; do the next exponent digit
.0005:
        LDX #'0'-1
        SEC
.0002:
        INX
        SBC #1000
        BCS .0002
        ADC #1000
        LSR Sendl
        BCS .00010
        CPX #'0'
        BEQ .0006
.00010:
        INC Sendl
        PHA
        TXA
        STA Decss+3,Y
        PLA
        INY
; and the next
.0006:
        LDX     #'0'-1
        SEC
.0003:
        INX
        SBC #100
        BCS .0003
        ADC #100
        LSR Sendl
        BCS .00011
        CPX #'0'
        BEQ .0007
.00011:
        INC Sendl
        PHA
        TXA
        STA Decss+3,Y
        PLA
        INY
 
.0007:
        LDX #'0'-1
        SEC
.0004:
        INX
        SBC #10
        BCS .0004
        ADC #10
        LSR Sendl
        BCS .00012
        CPX #'0'
        BEQ .0008
.00012:
        INC Sendl
        PHA
        TXA
        STA Decss+3,Y
        PLA
        INY
 
.0008:
        ADC #'0'
        STA Decss+3,Y
        LDA     #$00                    ; set null terminator
        STA     Decss+4,Y               ; save to output string
        RTS                                     ; go set string pointer (AY) and exit (branch always)
 
LAB_2A89
        STA     Decss,Y         ; save last character to output string
                                        ; set null terminator and exit
LAB_2A8C
        LDA     #$00                    ; set null terminator
        STA     Decss+1,Y               ; save after last character
 
LAB_2A91
;       LDA     #
;       LDY     #>Decssp1               ; set result string high pointer
        RTS
 
LAB_25FB:
        LDA             #FP_SWAP
        JSR             FPCommandWait
        LDY             #0
        TYX
.0002:
        LDA             (3,S),Y
        STA             FAC1,X
        INY
        INY
        INX
        INX
        CPX             #12
        BNE             .0002
        LDA             #FP_FIX2FLT
        JSR             FPCommandWait
FMUL:
        LDA             #FP_MUL
        JMP             FPCommandWait
 
LOAD_FAC2:
        PHX
        PHY
        LDY             #0
        TYX
.0002:
        LDA             (7,s),Y
        STA             FAC2,X
        INY
        INY
        INX
        INX
        CPX             #12
        BNE             .0002
        PLY
        PLX
        RTS
 
FloatToFixed:
        LDA             #FP_FLT2FIX
        JMP             FPCommandWait
 
AddPoint5:
        PEA             CONST_POINT5
        JSR             LOAD_FAC2
        PLA
        LDA             #FP_ADD
        JMP             FPCommandWait
 
MultiplyByTen:
        PEA             TEN_AS_FLOAT
        JSR             LOAD_FAC2
        PLA
        LDA             #FP_MUL
        JMP             FPCommandWait
 
public DivideByTen:
        PEA             TEN_AS_FLOAT
        JSR             LOAD_FAC2
        PLA
        JSR             SwapFACs
        LDA             #FP_DIV
        JMP             FPCommandWait
 
SwapFACs:
        LDA             #FP_SWAP
 
; Issue a command to the FP unit and wait for it to complete
;
public FPCommandWait:
        PHA
.0001:
        LDA             FP_STATREG      ; get the status register
        BIT             #$80            ; check for busy bit
        BNE             .0001           ; if busy go back
        PLA                                     ; to pop acc
        STA             FP_CMDREG       ; store the command
        RTS
 
; Display the FAC1 as a hex number
;
public DispFAC1:
        LDA FAC1_e
        JSR DispWord
        LDA     FAC1_1
        JSR     DispWord
        LDA FAC1_2
        JSR     DispWord
        LDA FAC1_3
        JSR DispWord
        LDA FAC1_4
        JSR DispWord
        LDA FAC1_5
        JSR DispWord
        LDA #' '
        JSR OutChar
        RTS
;
; 1,000,000 as a floating point number
;
A_MILLION:      ; $F4240
        dw              $0000
        dw              $0000
        dw              $0000
        dW              $0000
        dw              $7A12
        dw              $8013
 
CONST_100000:
        ;186A0
        dw              $0000
        dw              $0000
        dw              $0000
        dw              $0000
        dw              $61A8
        dw              $8010
; The constant 999999.4375 as hex
; 01.11_1010_0001_0001_1111_1011_1000_00000000000000000000000000
MAX_BEFORE_SCI:
        dw  $0000
        dw  $0000
        dw      $0000
        dw      $FB80
        dw      $7A11
        dw      $8013
 
TEN_AS_FLOAT:
        dw      $0000
        dw      $0000
        dw      $0000
        dw      $0000
        dw      $5000
        dw      $8003
 
; 99999.9375
; 01.10_0001_1010_0111_1111_1100_000000000000000000000000000000
;
CONST_9375:
        dw      $0000
        dw      $0000
        dw      $0000
        dw      $FC00
        dw      $61A7
        dw      $8010
 
; 0.5
CONST_POINT5:
        dw      $0000
        dw      $0000
        dw      $0000
        dw      $0000
        dw      $4000
        dw      $7FFF
 
; This table is used in converting numbers to ASCII.
 
LAB_2A9A
LAB_2A9B = LAB_2A9A+1
LAB_2A9C = LAB_2A9B+1
;       .word   $FFFF,$F21F,$494C,$589C,$0000
;       .word   $0000,$0163,$4578,$5D8A,$0000
;       .word   $FFFF,$FFDC,$790D,$903F,$0000
;       .word   $0000,$0003,$8D7E,$A4C6,$8000
;       .word   $FFFF,$FFFF,$A50C,$EF85,$C000
;       .word   $0000,$0000,$0918,$4E72,$A000
;       .word   $FFFF,$FFFF,$FF17,$2B5A,$F000
;       .word   $0000,$0000,$0017,$4876,$E800
;       .word   $FFFF,$FFFF,$FFFD,$ABF4,$1C00
;       .word   $0000,$0000,$0000,$3B9A,$CA00
;       .word   $FFFF,$FFFF,$FFFF,$FF67,$6980
;       .word   $0000,$0000,$0000,$05F5,$E100           ; 100000000
;       .word   $0000,$0000,$0098,$9680         ; 10000000
;       .word   $4240,$000F,$0000,$0000,$0000,$804E             ; 1000000
        .word   $86A0,$0001,$0000,$0000,$0000,$804E             ; 100000
        .word   $2710,$0000,$0000,$0000,$0000,$804E             ; 10000
        .word   $03E8,$0000,$0000,$0000,$0000,$804E             ; 1000
        .word   $0064,$0000,$0000,$0000,$0000,$804E             ; 100
FIXED10:
        .word   $000A,$0000,$0000,$0000,$0000,$804E             ; 10
        .word   $0001,$0000,$0000,$0000,$0000,$804E             ; 1
 
                 MEM    16
                 NDX    16

Browse

Tools

Subversion Repositories ft816float

[/] [ft816float/] [trunk/] [software/] [FAC1ToString.asm] - Blame information for rev 60

Line No.	Rev	Author	Line
1	4	robfinch	`; ============================================================================`
2			`; FAC1ToString.asm`
3			`; __`
4			`; \\__/ o\ (C) 2014 Robert Finch, Stratford`
5			`; \ __ / All rights reserved.`
6			`; \/_// robfinch@finitron.ca`
7			`; \|\|`
8			`;`
9			`;`
10			`; This source file is free software: you can redistribute it and/or modify`
11			`; it under the terms of the GNU Lesser General Public License as published`
12			`; by the Free Software Foundation, either version 3 of the License, or`
13			`; (at your option) any later version.`
14			`;`
15			`; This source file is distributed in the hope that it will be useful,`
16			`; but WITHOUT ANY WARRANTY; without even the implied warranty of`
17			`; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the`
18			`; GNU General Public License for more details.`
19			`;`
20			`; You should have received a copy of the GNU General Public License`
21			`; along with this program. If not, see .`
22			`;`
23			`; ============================================================================`
24			`;`
25			`; This code is a heavily modified version of the floating point to string`
26			`; conversion routine which is a part of Lee Davison's EhBASIC.`
27			`;`
28			`Cvaral = $95 ; current var address low byte`
29			`Cvarah = Cvaral+1 ; current var address high byte`
30			`numexp = $A8 ; string to float number exponent count`
31			`expcnt = $AA ; string to float exponent count`
32			`Sendl = $BA ; BASIC pointer temp low byte`
33			`Sendh = $BB ; BASIC pointer temp low byte`
34
35			`Decss = $3A0 ; number to decimal string start`
36			`Decssp1 = Decss+1 ; number to decimal string start`
37			`FP_ADD EQU 1`
38			`FP_SUB EQU 2`
39			`FP_MUL EQU 3`
40			`FP_DIV EQU 4`
41			`FP_FIX2FLT EQU 5`
42			`FP_FLT2FIX EQU 6`
43			`FP_ABS EQU 7`
44			`FP_NEG EQU 16`
45			`FP_SWAP EQU 17`
46			`FIXED_MUL EQU $83`
47			`FIXED_ADD EQU $81`
48			`FIXED_SUB EQU $82`
49			`;parameter FIXED_DIV = 8'h84;`
50			`;parameter FIXED_ABS = 8'h87;`
51			`;parameter FIXED_NEG = 8'h90;`
52			`FP_CMDREG EQU $FEA20E`
53			`FP_STATREG EQU $FEA20E`
54			`FAC1 EQU $FEA200`
55			`FAC1_5 EQU $FEA200`
56			`FAC1_4 EQU $FEA202`
57			`FAC1_3 EQU $FEA204`
58			`FAC1_2 EQU $FEA206`
59			`FAC1_1 EQU $FEA208`
60			`FAC1_msw EQU $FEA208`
61			`FAC1_e EQU $FEA20A`
62			`FAC2 EQU $FEA210`
63
64			`CPU W65C816S`
65			`NDX 16`
66			`MEM 16`
67
68
69			`public FAC1ToString:`
70
71			`; The first chunk of code determines if the number is positive or negative`
72			`; and spits out the appropriate sign. Next it takes the absolute value of`
73			`; the accumulator so following code only has to deal with positive numbers.`
74
75			`LDY #$00 ; set index = 1`
76			`LDA FAC1_msw ; test FAC1 sign (b15) (Can't use BIT)`
77			`BPL .0002 ; branch if +ve`
78			`LDA #'-' ; else character = "-"`
79			`STA Decss,Y ; save leading character (" " or "-")`
80			`LDA #FP_NEG ; make the FAC positive`
81			`JSR FPCommandWait`
82			`BRA .0001`
83			`.0002:`
84			`LDA #$20 ; character = " " (assume +ve)`
85			`STA Decss,Y`
86			`.0001:`
87			`STY Sendl ; save index`
88
89			`; This little bit of code check for a zero exponent which indicates a`
90			`; value of zero.`
91
92			`LDA FAC1_e ; get FAC1 exponent`
93			`TAX`
94			`BNE LAB_2989 ; branch if FAC1<>0`
95			`; exponent was $00 so FAC1 is 0`
96			`LDA #'0' ; set character = "0"`
97			`BRL LAB_2A89 ; save last character, [EOT] and exit`
98
99			`; This loop attempts to make small values more significant, so that there are`
100			`; fewer leading zeros in the value. (The exponent is decremented so that it`
101			`; corresponds). Because of the potential for extremely small values looping is`
102			`; limited. The problem is the 16 bit exponent can allow for much smaller`
103			`; values than an 8 bit exponent would and we don't want to loop for thousands`
104			`; of iterations in order to display a value that's almost zero.`
105
106			`; FAC1 is some non zero value`
107			`LAB_2989`
108			`STY Sendl ; save off .Y`
109			`LDY #1639 ; max number of retries`
110			`LDA #$00 ; clear (number exponent count)`
111			`STA numexp`
112			`LOOP_MBMILLION:`
113			`CPX #$8000 ; compare FAC1 exponent with $8000 (>1.00000)`
114			`BCS LAB_299A ; branch if FAC1=>1`
115			`; FAC1<1`
116			`PEA A_MILLION ; multiply FAC * 1,000,000`
117			`JSR LOAD_FAC2 ;`
118			`PLA ; get rid of parameter`
119			`JSR FMUL`
120			`LDA numexp`
121			`SEC`
122			`SBC #6 ; set number exponent count (-6)`
123			`STA numexp`
124			`LDA FAC1_e`
125			`TAX`
126			`DEY`
127			`BPL LOOP_MBMILLION`
128
129			`LAB_299A`
130			`LDY Sendl ; get back .Y`
131
132			`; These two loops coerce the value of the FAC to be between 100,000 and`
133			`; 1,000,000. This gives a maximum of six digits before the decimal point`
134			`; in scientific notation.`
135
136			`; This loop divides by 10 until the value in the FAC is less than 1,000,000`
137			`;`
138			`LOOP_DB10:`
139			`PEA MAX_BEFORE_SCI ; set pointer low byte to 999999.4375 (max before sci note)`
140			`JSR LOAD_FAC2 ; compare FAC1 with (AY)`
141			`PLA ; get rid of parameter`
142			`LDA FP_CMDREG`
143			`BIT #$08 ; test equals bit`
144			`BNE LAB_29C3 ; exit if FAC1 = (AY)`
145			`BIT #$04 ; test greater than bit`
146			`BEQ LOOP_MB10 ; go do *10 if FAC1 < (AY)`
147
148			`LAB_29B9`
149			`JSR DivideByTen ; divide by 10`
150			`INC numexp ; increment number exponent count`
151			`BRA LOOP_DB10 ; go test again (branch always)`
152
153			`; This loop multiplies the value by 10 until it's greater than`
154			`; 100,000.`
155			`; FAC1 < (AY)`
156			`LOOP_MB10`
157			`PEA CONST_9375 ; set pointer to 99999.9375`
158			`JSR LOAD_FAC2 ; compare FAC1 with (AY)`
159			`PLA ; get rid of parameter`
160			`LDA FP_CMDREG`
161			`BIT #$08`
162			`BNE LAB_29B2 ; branch if FAC1 = (AY) (allow decimal places)`
163			`BIT #$04`
164			`BNE LAB_29C0 ; branch if FAC1 > (AY) (no decimal places)`
165			`; FAC1 <= (AY)`
166			`LAB_29B2`
167			`JSR MultiplyByTen ; multiply by 10`
168			`DEC numexp ; decrement number exponent count`
169			`BRA LOOP_MB10 ; go test again (branch always)`
170
171			`; now we have just the digits to do`
172
173			`LAB_29C0`
174			`; JSR AddPoint5 ; add 0.5 to FAC1 (round FAC1)`
175			`LAB_29C3`
176			`; JSR FloatToFixed ; convert FAC1 floating-to-fixed`
177			`LDX #$01 ; set default digits before dp = 1`
178			`LDA numexp ; get number exponent count`
179			`CLC ; clear carry for add`
180			`ADC #$07 ; up to 6 digits before point`
181			`BMI LAB_29D8 ; if -ve then 1 digit before dp`
182
183			`CMP #$08 ; A>=8 if n>=1E6`
184			`BCS LAB_29D9 ; branch if >= $08`
185
186			`; carry is clear`
187			`TAX ; copy to A`
188			`DEX ; take 1 from digit count`
189			`LDA #$02 ;.set exponent adjust`
190
191			`LAB_29D8`
192			`SEC ; set carry for subtract`
193			`LAB_29D9`
194			`SBC #$02 ; -2`
195			`STA expcnt ;.save exponent adjust`
196			`STX numexp ; save digits before dp count`
197			`TXA ; copy to A`
198			`BEQ LAB_29E4 ; branch if no digits before dp`
199
200			`BPL LAB_29F7 ; branch if digits before dp`
201
202			`LAB_29E4`
203			`LDY Sendl ; get output string index`
204			`LDA #'.' ; character "."`
205			`INY ; increment index`
206			`STA Decss,Y ; save to output string`
207			`TXA ;.`
208			`BEQ LAB_29F5 ;.`
209
210			`LDA #'0' ; character "0"`
211			`INY ; increment index`
212			`STA Decss,Y ; save to output string`
213			`LAB_29F5`
214			`STY Sendl ; save output string index`
215
216			`LAB_29F7`
217			`LDX #'0' ; holds onto the digit value`
218
219			`; Now loop subtracting 100,000 as many times as we can. The value was coerced`
220			`; to be between 100,000 and 1,000,000. Count the number of times subtraction`
221			`; can be done successfully.`
222			`;`
223			`LAB_29FB`
224			`PEA CONST_100000`
225			`JSR LOAD_FAC2 ; load FAC2 with 100,000`
226			`PLA ; get rid of parameter`
227			`LDA FP_STATREG`
228			`BIT #$04 ; Is FAC1 > 100,000 ?`
229			`BEQ .0005 ; branch if not`
230			`LDA #FP_SWAP ; subtract is FAC2-FAC1!`
231			`JSR FPCommandWait;`
232			`LDA #FP_SUB ; subtract 100,000 from the mantissa.`
233			`JSR FPCommandWait`
234			`INX ; increment the value of the digit`
235			`BRA LAB_29FB ; try again`
236			`.0005:`
237			`TXA`
238			`LDY Sendl ; get output string index`
239			`INY ; increment output string index`
240			`TXA`
241			`STA Decss,Y ; save to output string`
242			`DEC numexp ; decrement # of characters before the dp`
243			`BNE LAB_2A3B ; branch if still characters to do`
244			`; else output the point`
245			`LDA #'.' ; character "."`
246			`INY ; increment output string index`
247			`STA Decss,Y ; save to output string`
248			`LAB_2A3B`
249			`STY Sendl ; save output string index`
250			`; We subtracted until the value was < 100,000 so multiply the`
251			`; remainder upwards to get the next digit.`
252			`JSR MultiplyByTen ; If not, multiply by 10`
253			`CPY #27 ; converted (+/- . incl)`
254			`BCC LAB_29F7`
255			`; now remove trailing zeroes`
256			`.RemoveTrailingZeros`
257			`LDA Decss,Y ; get character from output string`
258			`AND #$FF ; mask to a byte`
259			`DEY ; decrement output string index`
260			`CMP #'0' ; compare with "0"`
261			`BEQ .RemoveTrailingZeros ; loop until non "0" character found`
262
263			`CMP #'.' ; compare with "."`
264			`BEQ LAB_2A58 ; branch if was dp`
265
266			`; restore last character`
267			`INY ; increment output string index`
268			`LAB_2A58`
269			`LDA #'+' ; character "+"`
270			`LDX expcnt ; get exponent count`
271			`LBEQ LAB_2A8C ; if zero go set null terminator and exit`
272
273			`; exponent isn't zero so write exponent`
274			`BPL LAB_2A68 ; branch if exponent count +ve`
275
276			`LDA #$00 ; clear A`
277			`SEC ; set carry for subtract`
278			`SBC expcnt ; subtract exponent count adjust (convert -ve to +ve)`
279			`TAX ; copy exponent count to X`
280			`LDA #'-' ; character "-"`
281
282			`; We must keep moving forwards through the string because the acc is storing`
283			`; two bytes.`
284
285			`LAB_2A68`
286			`PHA`
287			`LDA #'E' ; character "E"`
288			`STA Decss+1,Y ; save exponent sign to output string`
289			`PLA`
290			`STA Decss+2,Y ; save to output string`
291			`TXA ; get exponent count back`
292
293			`; do highest exponent digit`
294			`STZ Sendl`
295			`LDX #'0'-1 ; one less than "0" character`
296			`SEC ; set carry for subtract`
297			`.0001:`
298			`INX ; count how many times we can subtract 10,000`
299			`SBC #10000`
300			`BCS .0001`
301			`ADC #10000`
302			`CPX #'0'`
303			`BEQ .0005`
304			`INC Sendl`
305			`PHA`
306			`TXA`
307			`STA Decss+3,Y`
308			`PLA`
309			`INY`
310			`; do the next exponent digit`
311			`.0005:`
312			`LDX #'0'-1`
313			`SEC`
314			`.0002:`
315			`INX`
316			`SBC #1000`
317			`BCS .0002`
318			`ADC #1000`
319			`LSR Sendl`
320			`BCS .00010`
321			`CPX #'0'`
322			`BEQ .0006`
323			`.00010:`
324			`INC Sendl`
325			`PHA`
326			`TXA`
327			`STA Decss+3,Y`
328			`PLA`
329			`INY`
330			`; and the next`
331			`.0006:`
332			`LDX #'0'-1`
333			`SEC`
334			`.0003:`
335			`INX`
336			`SBC #100`
337			`BCS .0003`
338			`ADC #100`
339			`LSR Sendl`
340			`BCS .00011`
341			`CPX #'0'`
342			`BEQ .0007`
343			`.00011:`
344			`INC Sendl`
345			`PHA`
346			`TXA`
347			`STA Decss+3,Y`
348			`PLA`
349			`INY`
350
351			`.0007:`
352			`LDX #'0'-1`
353			`SEC`
354			`.0004:`
355			`INX`
356			`SBC #10`
357			`BCS .0004`
358			`ADC #10`
359			`LSR Sendl`
360			`BCS .00012`
361			`CPX #'0'`
362			`BEQ .0008`
363			`.00012:`
364			`INC Sendl`
365			`PHA`
366			`TXA`
367			`STA Decss+3,Y`
368			`PLA`
369			`INY`
370
371			`.0008:`
372			`ADC #'0'`
373			`STA Decss+3,Y`
374			`LDA #$00 ; set null terminator`
375			`STA Decss+4,Y ; save to output string`
376			`RTS ; go set string pointer (AY) and exit (branch always)`
377
378			`LAB_2A89`
379			`STA Decss,Y ; save last character to output string`
380			`; set null terminator and exit`
381			`LAB_2A8C`
382			`LDA #$00 ; set null terminator`
383			`STA Decss+1,Y ; save after last character`
384
385			`LAB_2A91`
386			`; LDA #`
387			`; LDY #>Decssp1 ; set result string high pointer`
388			`RTS`
389
390			`LAB_25FB:`
391			`LDA #FP_SWAP`
392			`JSR FPCommandWait`
393			`LDY #0`
394			`TYX`
395			`.0002:`
396			`LDA (3,S),Y`
397			`STA FAC1,X`
398			`INY`
399			`INY`
400			`INX`
401			`INX`
402			`CPX #12`
403			`BNE .0002`
404			`LDA #FP_FIX2FLT`
405			`JSR FPCommandWait`
406			`FMUL:`
407			`LDA #FP_MUL`
408			`JMP FPCommandWait`
409
410			`LOAD_FAC2:`
411			`PHX`
412			`PHY`
413			`LDY #0`
414			`TYX`
415			`.0002:`
416			`LDA (7,s),Y`
417			`STA FAC2,X`
418			`INY`
419			`INY`
420			`INX`
421			`INX`
422			`CPX #12`
423			`BNE .0002`
424			`PLY`
425			`PLX`
426			`RTS`
427
428			`FloatToFixed:`
429			`LDA #FP_FLT2FIX`
430			`JMP FPCommandWait`
431
432			`AddPoint5:`
433			`PEA CONST_POINT5`
434			`JSR LOAD_FAC2`
435			`PLA`
436			`LDA #FP_ADD`
437			`JMP FPCommandWait`
438
439			`MultiplyByTen:`
440			`PEA TEN_AS_FLOAT`
441			`JSR LOAD_FAC2`
442			`PLA`
443			`LDA #FP_MUL`
444			`JMP FPCommandWait`
445
446			`public DivideByTen:`
447			`PEA TEN_AS_FLOAT`
448			`JSR LOAD_FAC2`
449			`PLA`
450			`JSR SwapFACs`
451			`LDA #FP_DIV`
452			`JMP FPCommandWait`
453
454			`SwapFACs:`
455			`LDA #FP_SWAP`
456
457			`; Issue a command to the FP unit and wait for it to complete`
458			`;`
459			`public FPCommandWait:`
460			`PHA`
461			`.0001:`
462			`LDA FP_STATREG ; get the status register`
463			`BIT #$80 ; check for busy bit`
464			`BNE .0001 ; if busy go back`
465			`PLA ; to pop acc`
466			`STA FP_CMDREG ; store the command`
467			`RTS`
468
469			`; Display the FAC1 as a hex number`
470			`;`
471			`public DispFAC1:`
472			`LDA FAC1_e`
473			`JSR DispWord`
474			`LDA FAC1_1`
475			`JSR DispWord`
476			`LDA FAC1_2`
477			`JSR DispWord`
478			`LDA FAC1_3`
479			`JSR DispWord`
480			`LDA FAC1_4`
481			`JSR DispWord`
482			`LDA FAC1_5`
483			`JSR DispWord`
484			`LDA #' '`
485			`JSR OutChar`
486			`RTS`
487			`;`
488			`; 1,000,000 as a floating point number`
489			`;`
490			`A_MILLION: ; $F4240`
491			`dw $0000`
492			`dw $0000`
493			`dw $0000`
494			`dW $0000`
495			`dw $7A12`
496			`dw $8013`
497
498			`CONST_100000:`
499			`;186A0`
500			`dw $0000`
501			`dw $0000`
502			`dw $0000`
503			`dw $0000`
504			`dw $61A8`
505			`dw $8010`
506			`; The constant 999999.4375 as hex`
507			`; 01.11_1010_0001_0001_1111_1011_1000_00000000000000000000000000`
508			`MAX_BEFORE_SCI:`
509			`dw $0000`
510			`dw $0000`
511			`dw $0000`
512			`dw $FB80`
513			`dw $7A11`
514			`dw $8013`
515
516			`TEN_AS_FLOAT:`
517			`dw $0000`
518			`dw $0000`
519			`dw $0000`
520			`dw $0000`
521			`dw $5000`
522			`dw $8003`
523
524			`; 99999.9375`
525			`; 01.10_0001_1010_0111_1111_1100_000000000000000000000000000000`
526			`;`
527			`CONST_9375:`
528			`dw $0000`
529			`dw $0000`
530			`dw $0000`
531			`dw $FC00`
532			`dw $61A7`
533			`dw $8010`
534
535			`; 0.5`
536			`CONST_POINT5:`
537			`dw $0000`
538			`dw $0000`
539			`dw $0000`
540			`dw $0000`
541			`dw $4000`
542			`dw $7FFF`
543
544			`; This table is used in converting numbers to ASCII.`
545
546			`LAB_2A9A`
547			`LAB_2A9B = LAB_2A9A+1`
548			`LAB_2A9C = LAB_2A9B+1`
549			`; .word $FFFF,$F21F,$494C,$589C,$0000`
550			`; .word $0000,$0163,$4578,$5D8A,$0000`
551			`; .word $FFFF,$FFDC,$790D,$903F,$0000`
552			`; .word $0000,$0003,$8D7E,$A4C6,$8000`
553			`; .word $FFFF,$FFFF,$A50C,$EF85,$C000`
554			`; .word $0000,$0000,$0918,$4E72,$A000`
555			`; .word $FFFF,$FFFF,$FF17,$2B5A,$F000`
556			`; .word $0000,$0000,$0017,$4876,$E800`
557			`; .word $FFFF,$FFFF,$FFFD,$ABF4,$1C00`
558			`; .word $0000,$0000,$0000,$3B9A,$CA00`
559			`; .word $FFFF,$FFFF,$FFFF,$FF67,$6980`
560			`; .word $0000,$0000,$0000,$05F5,$E100 ; 100000000`
561			`; .word $0000,$0000,$0098,$9680 ; 10000000`
562			`; .word $4240,$000F,$0000,$0000,$0000,$804E ; 1000000`
563			`.word $86A0,$0001,$0000,$0000,$0000,$804E ; 100000`
564			`.word $2710,$0000,$0000,$0000,$0000,$804E ; 10000`
565			`.word $03E8,$0000,$0000,$0000,$0000,$804E ; 1000`
566			`.word $0064,$0000,$0000,$0000,$0000,$804E ; 100`
567			`FIXED10:`
568			`.word $000A,$0000,$0000,$0000,$0000,$804E ; 10`
569			`.word $0001,$0000,$0000,$0000,$0000,$804E ; 1`
570
571			`MEM 16`
572			`NDX 16`