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;;
;; Copyright (c) 2016 Marco Granati <mg@unet.bz>
;;
;; Permission to use, copy, modify, and distribute this software for any
;; purpose with or without fee is hereby granted, provided that the above
;; copyright notice and this permission notice appear in all copies.
;;
;; THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
;; WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
;; MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
;; ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
;; WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
;; ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
;; OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
;;

;; name: dpfpu.inc      
;; rev.: 2016/03/30
;; o.s. 65C816 version v1.0

.LIST on

; direct page for flotaing point unit
_DPFPU: .SECTION page0, common, ref_only, offset 0      ;FPU D.P.

MNTBITS         .EQU    (16*8)  ; significand bits + guard bits
MANTSIZ         .EQU    16      ; significand size
FREGSIZ         .EQU    20      ; floating point register size

tm              .DS     16      ; temp. mantissa

fsubnf          .DB             ; subnormal flag used by fac2dec
atncode         .EQU    fsubnf  ; fatanyx octant

sgncmp          .DB             ; sign comparison: fac vs. arg

; floating Point accumulator (fac)
facm            .DS     16      ; guard bits (32 bits)+significand (80 bits)
facexp          .DW             ; fac biased exponent
facsgn          .DB             ; fac mantissa sign
facst           .DB             ; fac status for floating point
                                ; <7>: 1 if fac is invalid (nan or inf)
                                ; <6>: 1 if fac=inf (with <7>=1)   
                                ;      0 if fac=nan (with <7>=1)   
                                ; <6>: 1 if fac=0   (with <7>=0)
                                ; <5>: always '0'

                                ; fac status for long integer
                                ; <7>: 1 if facm will be regarded as 'signed'
                                ; <6>: 1 if facm = 0
                                ; <5>: always '1'

fexph           .DW             ; unbiased fac exponent sign extension
facext          .DW             ; fac guard bits extension
wftmp2          .EQU    facext
facsiz          .EQU    facsgn  ; integer only: size in bytes   

; floating point operand (arg)
argm            .DS     16      ; guard bits (32 bits)+significand (80 bits)
argexp          .DW             ; arg biased exponent
argsgn          .DB             ; arg mantissa sign
argst           .DB             ; arg status for floating point
                                ; <7>: 1 if arg is invalid (nan or inf)
                                ; <6>: 1 if arg=inf (with <7>=1)   
                                ;      0 if arg=nan (with <7>=1)   
                                ; <6>: 1 if arg=0   (with <7>=0)

                                ; arg status for long integer
                                ; <7>: 1 if facm will be regarded as 'signed'
                                ; <6>: 1 if facm = 0
                                ; <5>: always '1'
                        
aexph           .DW             ; unbiased arg exponent sign extension
argext          .DW

wftmp           .EQU    aexph   ; temp. word (int2dec, fpadd, fpsub)
argsiz          .EQU    argsgn  ; integer only: size in bytes   

fcp             LP              ; long pointer to flaot constants
scsgn           .DB             ; scaling sign
scexp           .DW             ; scaling value
dexp            .DW             ; decimal exponent
dsgn            .DB             ; decimal float sign
pdeg            .DB             ; polyn. degree
powfg           .EQU    pdeg    ; flag used by fpowxy

tlp             LP              ; string long pointer
fpidx           .DB             ; string index
                
tfr0            .DS     20      ; temp. float reg. 0
tfr1            .DS     20      ; temp. float reg. 1
tfr2            .DS     20      ; temp. float reg. 2
tfr3            .DS     20      ; temp. float reg. 3
tfr4            .DS     20      ; temp. float reg. 4
tfr5            .DS     20      ; temp. float reg. 5
                .DS     4       ; used by xcvt: doesn't change

XCVTEND         .EQU    ($ - 1) ; last byte of xcvt buffer

; buffer used by decimal conversion (overlap tfr0&tfr1: 40 bytes)
fpstr           .EQU    tfr0    ; 40 bytes buffer
; buffer used to format a decimal string
xcvt            .EQU    tfr2    ; 84 bytes buffer

fcpc0           .EQU    tfr5    ; constants pointer for exp. function
fcpc1           .EQU    tfr5+2
fcpc2           .EQU    tfr5+4
fcpp            .EQU    tfr5+6
fcpq            .EQU    tfr5+8
fcpd            .EQU    tfr5+10
fcqd            .EQU    tfr5+11
fcpolf          .EQU    tfr5+12 ; polynomial flag

tmdot           .EQU    tfr5    ; digit count after decimal dot
tmpa            .EQU    tfr5+2  ; temp: save A&Y
tmpy            .EQU    tfr5+3
tmsgn           .EQU    tfr5+4  ; temp.: significand sign
tmcnt           .EQU    tfr5+5  ; temp.: significand digits count
tesgn           .EQU    tfr5+6  ; temp.: exponent sign 
tecnt           .EQU    tfr5+7  ; temp.: exponent digits count

mcand1          .EQU    tfr5+8  ; multiplicand's 
mcand2          .EQU    tfr5+10
mcsgn           .EQU    tfr5+12
dvsor           .EQU    tfr5+14
quot            .EQU    tfr5+16

fpprec          .DW             ; precision
fpfmt           .DB             ; format
fpaltf          .DB             ; alternate format
fpcap           .DB             ; adding for lower case
fpstyle         .DB             ; flag 'F' style
fpdot           .EQU    pdeg    ; decimal dot flag
fpoct           .EQU    fpfmt   ; octant (circular func's)
fpcsgn          .EQU    fpaltf  ; circular func's: argument sign
fpcot           .EQU    fpcap   ; cotangent flag
fpasin          .EQU    fpcap   ; asin flag

dummy           .DB

        .ENDS
.LIST off

; pi 4000 921f b544 42d1 8469 898c c517 01b8   = 3.1415926535897932384626433832795028
; 4000 C90FDAA22168C234C4C6628B80DC1CD2
; $D1,$1C,$DC,$80,$8B,$62,$C6,$C4,$34,$C2,$68,$21,$A2,$DA,$0F,$C9,$00,$40
; 4000 C90FDAA22168C234C4C6628B80DC1CD1 40