File:  [gforth] / gforth / float.fs
Revision 1.30: download - view: text, annotated - select for diffs
Mon Jan 17 00:04:29 2000 UTC (19 years, 10 months ago) by pazsan
Branches: MAIN
CVS tags: HEAD
Fixed ugly field definition in float.fs
Added correct IEEE handling of -0 in >float

    1: \ High level floating point                            14jan94py
    2: 
    3: \ Copyright (C) 1995,1997 Free Software Foundation, Inc.
    4: 
    5: \ This file is part of Gforth.
    6: 
    7: \ Gforth is free software; you can redistribute it and/or
    8: \ modify it under the terms of the GNU General Public License
    9: \ as published by the Free Software Foundation; either version 2
   10: \ of the License, or (at your option) any later version.
   11: 
   12: \ This program is distributed in the hope that it will be useful,
   13: \ but WITHOUT ANY WARRANTY; without even the implied warranty of
   14: \ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   15: \ GNU General Public License for more details.
   16: 
   17: \ You should have received a copy of the GNU General Public License
   18: \ along with this program; if not, write to the Free Software
   19: \ Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
   20: 
   21: \ 1 cells 4 = [IF]
   22: \ ' cells   Alias sfloats
   23: \ ' cell+   Alias sfloat+
   24: \ ' align   Alias sfalign
   25: \ ' aligned Alias sfaligned
   26: \ [ELSE]
   27: \ : sfloats  2* 2* ;
   28: \ : sfloat+  4 + ;
   29: \ : sfaligned ( addr -- addr' )  3 + -4 and ;
   30: \ : sfalign ( -- )  here dup sfaligned swap ?DO  bl c,  LOOP ;
   31: \ [THEN]
   32: 
   33: \ 1 floats 8 = [IF]
   34: \ ' floats   Alias dfloats
   35: \ ' float+   Alias dfloat+
   36: \ ' falign   Alias dfalign
   37: \ ' faligned Alias dfaligned
   38: \ [ELSE]
   39: \ : dfloats  2* 2* 2* ;
   40: \ : dfloat+  8 + ;
   41: \ : dfaligned ( addr -- addr' )  7 + -8 and ;
   42: \ : dfalign ( -- )  here dup dfaligned swap ?DO  bl c,  LOOP ;
   43: \ [THEN]
   44: 
   45: : sfalign ( -- ) \ float-ext s-f-align
   46:     \G If the data-space pointer is not single-float-aligned, reserve
   47:     \G enough space to align it.
   48:     here dup sfaligned swap ?DO  bl c,  LOOP ;
   49: : dfalign ( -- ) \ float-ext d-f-align
   50:     \G If the data-space pointer is not double-float-aligned, reserve
   51:     \G enough space to align it.
   52:     here dup dfaligned swap ?DO  bl c,  LOOP ;
   53: 
   54: 1 sfloats (Field) sfloat+ , ( sf-addr1 -- sf-addr2 ) \ float-ext s-float-plus
   55: \G Increment @i{sf-addr1} by the number of address units corresponding to the size of
   56: \G a single-precision IEEE floating-point number, to give @i{sf-addr2}.""
   57: 
   58: 1 dfloats (Field) dfloat+ , ( df-addr1 -- df-addr2 ) \ float-ext d-float-plus
   59: \G Increment @i{df-addr1} by the number of address units corresponding to the size of
   60: \G a double-precision IEEE floating-point number, to give @i{df-addr2}.""
   61: 
   62: : f, ( f -- ) \ gforth
   63:     \G Reserve data space for one floating-point number and store
   64:     \G @i{f} in the space.
   65:     here 1 floats allot f! ;
   66: 
   67: : fconstant  ( r "name" -- ) \ float f-constant
   68:     Create f,
   69: DOES> ( -- r )
   70:     f@ ;
   71: 
   72: : fdepth ( -- +n ) \ float f-depth
   73:     \G @i{+n} is the current number of (floating-point) values on the
   74:     \G floating-point stack.
   75:     fp0 @ fp@ - [ 1 floats ] Literal / ;
   76: 
   77: : FLit ( -- r )  r> dup f@ float+ >r ;
   78: : FLiteral ( compilation r -- ; run-time -- r ) \ float f-literal
   79:     \G Compile appropriate code such that, at run-time, @i{r} is placed
   80:     \G on the (floating-point) stack. Interpretation semantics are undefined.
   81:     BEGIN  here cell+ dup faligned <>  WHILE  postpone noop  REPEAT
   82:     postpone FLit  f, ;  immediate
   83: 
   84: &15 Value precision ( -- u ) \ float-ext
   85: \G @i{u} is the number of significant digits currently used by
   86: \G @code{F.} @code{FE.} and @code{FS.} 
   87: : set-precision ( u -- ) \ float-ext
   88:     \G Set the number of significant digits currently used by
   89:     \G @code{F.} @code{FE.} and @code{FS.} to @i{u}.
   90:     to precision ;
   91: 
   92: : scratch ( r -- addr len )
   93:   pad precision - precision ;
   94: 
   95: : zeros ( n -- )   0 max 0 ?DO  '0 emit  LOOP ;
   96: 
   97: : -zeros ( addr u -- addr' u' )
   98:   BEGIN  dup  WHILE  1- 2dup + c@ '0 <>  UNTIL  1+  THEN ;
   99: 
  100: : f$ ( f -- n )  scratch represent 0=
  101:   IF  2drop  scratch 3 min type  rdrop  EXIT  THEN
  102:   IF  '- emit  THEN ;
  103: 
  104: : f.  ( r -- ) \ float-ext f-dot
  105: \G Display (the floating-point number) @i{r} using fixed-point notation,
  106: \G followed by a space.
  107:   f$ dup >r 0<
  108:   IF    '0 emit
  109:   ELSE  scratch r@ min type  r@ precision - zeros  THEN
  110:   '. emit r@ negate zeros
  111:   scratch r> 0 max /string 0 max -zeros type space ;
  112: \ I'm afraid this does not really implement ansi semantics wrt precision.
  113: \ Shouldn't precision indicate the number of places shown after the point?
  114: 
  115: : fe. ( r -- ) \ float-ext f-e-dot
  116: \G Display @i{r} using engineering notation, followed by a space.
  117:   f$ 1- s>d 3 fm/mod 3 * >r 1+ >r
  118:   scratch r@ min type '. emit  scratch r> /string type
  119:   'E emit r> . ;
  120: 
  121: : fs. ( r -- ) \ float-ext f-s-dot
  122: \G Display @i{r} using scientific notation, followed by a space.
  123:   f$ 1-
  124:   scratch over c@ emit '. emit 1 /string type
  125:   'E emit . ;
  126: 
  127: require debugs.fs
  128: 
  129: : sfnumber ( c-addr u -- r true | false )
  130:     2dup [CHAR] e scan ( c-addr u c-addr2 u2 )
  131:     dup 0=
  132:     IF
  133: 	2drop 2dup [CHAR] E scan ( c-addr u c-addr3 u3 )
  134:     THEN
  135:     nip
  136:     IF
  137: 	>float
  138:     ELSE
  139: 	2drop false
  140:     THEN ;
  141: 
  142: :noname ( c-addr u -- )
  143:     2dup sfnumber
  144:     IF
  145: 	2drop POSTPONE FLiteral
  146:     ELSE
  147: 	defers compiler-notfound
  148:     ENDIF ;
  149: IS compiler-notfound
  150: 
  151: :noname ( c-addr u -- r )
  152:     2dup sfnumber
  153:     IF
  154: 	2drop
  155:     ELSE
  156: 	defers interpreter-notfound
  157:     ENDIF ;
  158: IS interpreter-notfound
  159: 
  160: : fvariable ( "name" -- ) \ float f-variable
  161:     Create 0.0E0 f, ;
  162:     \ does> ( -- f-addr )
  163: 
  164: 1.0e0 fasin 2.0e0 f* fconstant pi ( -- r ) \ gforth
  165: \G @code{Fconstant} -- @i{r} is the value pi; the ratio of a circle's area
  166: \G to its diameter.
  167: 
  168: : f2* ( r1 -- r2 ) \ gforth
  169:     \G Multiply @i{r1} by 2.0e0
  170:     2.0e0 f* ;
  171: 
  172: : f2/ ( r1 -- r2 ) \ gforth
  173:     \G Multiply @i{r1} by 0.5e0
  174:     0.5e0 f* ;
  175: 
  176: : 1/f ( r1 -- r2 ) \ gforth
  177:     \G Divide 1.0e0 by @i{r1}.
  178:     1.0e0 fswap f/ ;
  179: 
  180: 
  181: \ We now have primitives for these, so we need not define them
  182: 
  183: \ : falog ( f -- 10^f )  [ 10.0e0 fln ] FLiteral f* fexp ;
  184: 
  185: \ : fsinh    fexpm1 fdup fdup 1.0e0 f+ f/ f+ f2/ ;
  186: \ : fcosh    fexp fdup 1/f f+ f2/ ;
  187: \ : ftanh    f2* fexpm1 fdup 2.0e0 f+ f/ ;
  188: 
  189: \ : fatanh   fdup f0< >r fabs 1.0e0 fover f- f/  f2* flnp1 f2/
  190: \            r> IF  fnegate  THEN ;
  191: \ : facosh   fdup fdup f* 1.0e0 f- fsqrt f+ fln ;
  192: \ : fasinh   fdup fdup f* 1.0e0 f+ fsqrt f/ fatanh ;
  193: 
  194: : f~abs ( r1 r2 r3 -- flag ) \ gforth
  195:     \G Approximate equality with absolute error: |r1-r2|<r3.
  196:     frot frot f- fabs fswap f< ;
  197: 
  198: : f~rel ( r1 r2 r3 -- flag ) \ gforth
  199:     \G Approximate equality with relative error: |r1-r2|<r3*|r1+r2|.
  200: 	frot frot fover fabs fover fabs f+ frot frot
  201: 	f- fabs frot frot f* f< ;
  202: 
  203: : f~ ( r1 r2 r3 -- flag ) \ float-ext f-proximate
  204:     \G ANS Forth medley: r3>0: @code{f~abs}; r3=0: r1=r2; r3<0: @code{fnegate f~rel}.
  205:     fdup f0=
  206:     IF
  207: 	fdrop f=  \ !! this does not work, because 0=-0 with f= on Linux-Intel
  208: 	          \ the standard says they should compare unequal
  209: 		  \ the comparison should be done with COMPARE
  210: 	EXIT
  211:     THEN
  212:     fdup f0>
  213:     IF
  214: 	f~abs
  215:     ELSE
  216: 	fnegate f~rel
  217:     THEN ;
  218: 
  219: : f.s ( -- ) \ gforth f-dot-s
  220:     \G Display the number of items on the floating-point stack,
  221:     \G followed by a list of the items; TOS is the right-most item.
  222:     ." <" fdepth 0 .r ." > " fdepth 0 max maxdepth-.s @ min dup 0 
  223:     ?DO  dup i - 1- floats fp@ + f@ f.  LOOP  drop ; 

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