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strtof.s
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strtof.s
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/**************************************************************************
Copyright Jacques Deschênes 2021,2022
This file is part of beyond-Jupiter
beyond-Jupiter is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
beyond-Jupiter 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 beyond-Jupiter. If not, see <http://www.gnu.org/licenses/>.
***************************************************************************/
/*******************************
float number parser
*******************************/
/********************
10^2^n
for n in [0..5]
********************/
p10p2n: .word 0x41200000 // 10.0
.word 0x42C80000 // 100.0
.word 0x461C4000 // 10000.0
.word 0x4CBEBC20 // 1.0e8
.word 0x5A0E1BCA // 1.0e16
.word 0x749DC5AE // 1.0e32
fzero = 0x0
fone = 0x3F800000
fminus1 = 0xBF800000
ften = 0x41200000
// P10P2N@ ( idx -- f )
// fetch element from p10p2n array
p10p2at: // ( idx -- f )
_NEST
_DOLIT 2
_ADR LSHIFT
_DOLIT p10p2n
_ADR PLUS
_ADR AT
_UNNEST
// check if exponent bit at idx position is
// set or reset
bit_state: // ( idx f e -- idx f bit )
_NEST
_DOLIT 1 // idx f e 1
_DOLIT 3 // idx f e 1 3
_ADR PICK // idx f e 1 idx
_ADR LSHIFT // idx f e bit_mask
_ADR ANDD // idx f bit, i.e. 0||1<<idx
_UNNEST
// mant_div ( 0 f e -- f )
// negative exponent, divide mantissa
// to adjust from decimal to binary exponent.
// input:
// 0 exponent bit counter
// f mantissa converted float
// e decimal exponent
// output:
// f float adjusted
mant_div:
_NEST
_ADR TOR // idx f R: e
div_loop:
_ADR RAT // idx f e R: e
_ADR bit_state // idx f state
_QBRAN 1f // bit reset
_ADR OVER
_ADR p10p2at // idx f pwr10 R: e
_ADR FSLH // idx f R: e
1: _ADR SWAP // f idx R: e
_ADR ONEP // F idx++ R: e
_ADR SWAP // idx f
_ADR OVER // idx f idx
_DOLIT 5
_ADR GREAT // idx > 5
_QBRAN div_loop
_ADR RFROM
_ADR DROP
_UNNEST
// mant_mult ( 0 f e -- f )
// positive exponent, multiply mantissa
// to adjust from decimal to binary exponent
// input:
// 0 exponent bit counter
// f mantissa converted float
// e decimal exponent
// output:
// f float adjusted
mant_mult:
_NEST
_ADR TOR
mult_loop:
_ADR RAT // idx f e R: e
_ADR bit_state // idx f state
_QBRAN 1f // bit reset
_ADR OVER
_ADR p10p2at // idx f pwr10 R: e
_ADR FSTAR // idx f R: e
1: _ADR SWAP // f idx R: e
_ADR ONEP // F idx++ R: e
_ADR SWAP // idx f
_ADR OVER // idx f idx
_DOLIT 5
_ADR GREAT // idx > 5
_QBRAN mult_loop
_ADR RFROM
_ADR DROP
_UNNEST
// float adjustment from decimal exponent
// multiply or divide mantissa by exponent
// if exponant < 0 divide
// if exponant >0 multiply
// if exponant == 0 done
exp_adjust: // ( e f -- f )
_NEST
_ADR OVER // e f e
_QBRAN 3f // exp==0, done
_DOLIT 0 // e f idx
_ADR NROT // idx e f
_ADR SWAP // idx f e
_ADR DUPP // idx f e e
_ADR ZLESS
_QBRAN pos_exp
// negative exponent
_ADR ABSS
_ADR mant_div
_BRAN 3f
pos_exp: // positive exponent
_ADR mant_mult
// adjustment done
3: _ADR SWAP
_ADR DROP
_UNNEST
/********************************
integer ( a cnt -- a+ cnt- f# )
*********************************/
integer:
_NEST
_DOLIT 0
_ADR DUPP
_ADR DSWAP // 0 0 a cnt
_ADR TONBR // d a+ cnt-
_ADR DSWAP
_ADR DTOS
_ADR STOF
_UNNEST
/*****************************
decimals ( a cnt -- a+ cnt- fdec )
parse digits after '.'
convert to float
*****************************/
decimals:
_NEST
_ADR DUPP
_ADR TOR
_DOLIT 0
_ADR DUPP
_ADR DSWAP
_ADR TONBR // -- d a+ cnt-
_ADR DSWAP // a+ cnt- d
_ADR DTOS // a+ cnt- i
_ADR STOF // convert integer to float
_ADR RFROM // a+ cnt- f# cnt
_DOLIT 2
_ADR PICK
_ADR SUBB
_DOLIT 9
_ADR MIN
_ADR PWR10
_ADR FSLH // a+ cnt- fdec
_UNNEST
/************************************
exponent ( a cnt -- a+ cnt- exp )
parse float exponent
************************************/
exponent:
_NEST
_ADR NEGQ
_ADR TOR
_DOLIT 0
_ADR DUPP
_ADR DSWAP // 0 0 a cnt
_ADR TONBR // d a cnt
_ADR DSWAP
_ADR DTOS
_ADR RFROM
_QBRAN 1f
_ADR NEGAT
1:
_UNNEST // -- a+ cnt- exp
/**********************************
FLOAT? ( a -- f# -2 | a 0 )
parse float number
return ( a 0 ) if not float
**********************************/
_HEADER FLOATQ,6,"FLOAT?"
_NEST
// always use base 10
// hexadecimal float not accepted
_ADR BASE
_ADR AT
_ADR TOR
// use decimal base
_ADR DECIM
// save string pointer
_ADR DUPP
_ADR TOR // base a
_ADR COUNT // a+ cnt // cnt is length of string
// check for '-'|'+' save sign on R
_ADR NEGQ
_ADR TOR // -- a+ cnt- R: base a sign
// check if begin with '.'
_DOLIT 0
_ADR TOR // r: base a sign fint
_DOLIT '.'
_ADR CHARQ
_TBRAN get_decimals
// if 'E' error
_DOLIT 'E'
_ADR CHARQ
_TBRAN error2
// drop fint
_ADR RFROM
_ADR DROP
_ADR integer // a+ cnt- fint
_ADR TOR // a 0 a+ cnt- flag r: base a sign fint
// must be '.' | 'E'
_DOLIT '.'
_ADR CHARQ
_TBRAN get_decimals
_DOLIT 'E'
_ADR CHARQ
_QBRAN error2 // r: base a sign fint
_DOLIT 0
_ADR TOR // r: base a sign fint ffrac
_BRAN get_exponent
get_decimals:
_ADR decimals
_ADR TOR // a 0 a+ cnt- r: base sign fint ffrac
_ADR DUPP
_QBRAN f_done
try_e:
// if next char is 'E' get exponent
_DOLIT 'E'
_ADR CHARQ
_TBRAN get_exponent
_BRAN error3
f_done:
_DOLIT fzero
_ADR TOR // a 0 a+ cnt- r: base sign fint ffrac fexp
_BRAN build_float
get_exponent:
_ADR exponent // -- a 0 a+ cnt- exp
_ADR TOR // a 0 a+ cnt- r: base sign fint ffrac exp
_ADR DUPP
_TBRAN error4 // count must be 0
build_float: // a+ cnt- R: base a sign fint fdec exp
_ADR DDROP
_ADR RFROM
_ADR DRFROM
_ADR FPLUS
_ADR exp_adjust
_ADR RFROM
_QBRAN 1f
_DOLIT fminus1
_ADR FSTAR
1: _DOLIT -2
_ADR RFROM
_ADR DROP
_BRAN restore_base
error2: // a cnt R: base a sign fint
_ADR DDROP
_BRAN e4
error3: // a cnt R: base a sign fint fdec
_ADR DDROP // -- R: base a sign
_ADR RFROM
_ADR DROP
_BRAN e4
error4: // a+ cnt- r: base sign fint ffrac fexp
_ADR DDROP
_ADR DRFROM
_ADR DDROP
e4: _ADR DRFROM
_ADR DDROP
_ADR RFROM
_DOLIT 0
restore_base:
_ADR RFROM
_ADR BASE
_ADR STORE
_UNNEST