Diff for /gforth/Attic/gforth.ds between versions 1.4 and 1.10

version 1.4, 1995/01/10 18:57:43 version 1.10, 1995/02/09 17:49:55
Line 428  unwary (e.g., floating point addition is Line 428  unwary (e.g., floating point addition is
 for the wary. You should not use them unless you know what you are doing  for the wary. You should not use them unless you know what you are doing
 or you don't care that the results you get are totally bogus. If you  or you don't care that the results you get are totally bogus. If you
 want to learn about the problems of floating point numbers (and how to  want to learn about the problems of floating point numbers (and how to
 avoid them), you might start with @cite{Goldberg, What every computer  avoid them), you might start with @cite{David (?) Goldberg, What Every
 scientist should know about floating-point numbers, Computing Surveys  Computer Scientist Should Know About Floating-Point Arithmetic, ACM
 ?}.  Computing Surveys 23(1):5@minus{}48, March 1991}.
   
 doc-f+  doc-f+
 doc-f-  doc-f-
Line 449  doc-fexpm1 Line 449  doc-fexpm1
 doc-fln  doc-fln
 doc-flnp1  doc-flnp1
 doc-flog  doc-flog
   doc-falog
 doc-fsin  doc-fsin
 doc-fcos  doc-fcos
 doc-fsincos  doc-fsincos
Line 606  The standard guarantees that addresses r Line 607  The standard guarantees that addresses r
 are cell-aligned; in addition, gforth guarantees that these addresses  are cell-aligned; in addition, gforth guarantees that these addresses
 are aligned for all purposes.  are aligned for all purposes.
   
   Note that the standard defines a word @code{char}, which has nothing to
   do with address arithmetic.
   
 doc-chars  doc-chars
 doc-char+  doc-char+
 doc-cells  doc-cells
Line 624  doc-dfloats Line 628  doc-dfloats
 doc-dfloat+  doc-dfloat+
 doc-dfalign  doc-dfalign
 doc-dfaligned  doc-dfaligned
   doc-maxalign
   doc-maxaligned
   doc-cfalign
   doc-cfaligned
 doc-address-unit-bits  doc-address-unit-bits
   
 @node Memory block access,  , Address arithmetic, Memory access  @node Memory block access,  , Address arithmetic, Memory access
Line 800  Therefore we recommend avoiding using @c Line 808  Therefore we recommend avoiding using @c
 @var{n}. One alternative is @code{@var{n} S+LOOP}, where the negative  @var{n}. One alternative is @code{@var{n} S+LOOP}, where the negative
 case behaves symmetrical to the positive case:  case behaves symmetrical to the positive case:
   
 @code{-2 0 ?DO  i .  -1 +LOOP}  prints @code{0 -1}  @code{-2 0 ?DO  i .  -1 S+LOOP}  prints @code{0 -1}
   
 @code{-1 0 ?DO  i .  -1 +LOOP}  prints @code{0}  @code{-1 0 ?DO  i .  -1 S+LOOP}  prints @code{0}
   
 @code{ 0 0 ?DO  i .  -1 +LOOP}  prints nothing  @code{ 0 0 ?DO  i .  -1 S+LOOP}  prints nothing
   
 The loop is terminated when the border between @var{limit@minus{}sgn(n)} and  The loop is terminated when the border between @var{limit@minus{}sgn(n)} and
 @var{limit} is crossed. However, @code{S+LOOP} is not part of the ANS  @var{limit} is crossed. However, @code{S+LOOP} is not part of the ANS
Line 877  doc-next Line 885  doc-next
 doc-leave  doc-leave
 doc-?leave  doc-?leave
 doc-unloop  doc-unloop
 doc-undo  doc-done
   
 The standard does not allow using @code{cs-pick} and @code{cs-roll} on  The standard does not allow using @code{cs-pick} and @code{cs-roll} on
 @i{do-sys}. Our system allows it, but it's your job to ensure that for  @i{do-sys}. Our system allows it, but it's your job to ensure that for
 every @code{?DO} etc. there is exactly one @code{UNLOOP} on any path  every @code{?DO} etc. there is exactly one @code{UNLOOP} on any path
 through the definition (@code{LOOP} etc. compile an @code{UNLOOP} on the  through the definition (@code{LOOP} etc. compile an @code{UNLOOP} on the
 fall-through path). Also, you have to ensure that all @code{LEAVE}s are  fall-through path). Also, you have to ensure that all @code{LEAVE}s are
 resolved (by using one of the loop-ending words or @code{UNDO}).  resolved (by using one of the loop-ending words or @code{DONE}).
   
 Another group of control structure words are  Another group of control structure words are
   
Line 1037  locals are initialized with values from Line 1045  locals are initialized with values from
 Currently there is no way to define locals with user-defined data  Currently there is no way to define locals with user-defined data
 structures, but we are working on it.  structures, but we are working on it.
   
 GNU Forth allows defining locals everywhere in a colon definition. This poses the following questions:  GNU Forth allows defining locals everywhere in a colon definition. This
   poses the following questions:
   
 @menu  @menu
 * Where are locals visible by name?::    * Where are locals visible by name?::  
Line 1496  locals wordset. Line 1505  locals wordset.
 @node Programming Tools, Threading Words, Other I/O, Words  @node Programming Tools, Threading Words, Other I/O, Words
 @section Programming Tools  @section Programming Tools
   
 @node  @menu
   * Debugging::                   Simple and quick.
   * Assertions::                  Making your programs self-checking.
   @end menu
   
   @node Debugging, Assertions, Programming Tools, Programming Tools
 @subsection Debugging  @subsection Debugging
   
 The simple debugging aids provided in @file{debugging.fs}  The simple debugging aids provided in @file{debugging.fs}
Line 1516  query-replace them with nothing). The de Line 1530  query-replace them with nothing). The de
 @code{printdebugdata} and @code{printdebugline} control the output of  @code{printdebugdata} and @code{printdebugline} control the output of
 @code{~~}. The default source location output format works well with  @code{~~}. The default source location output format works well with
 Emacs' compilation mode, so you can step through the program at the  Emacs' compilation mode, so you can step through the program at the
 source level using @kbd{C-x `}.  source level using @kbd{C-x `} (the advantage over a stepping debugger
   is that you can step in any direction and you know where the crash has
   happened or where the strange data has occurred).
   
 Note that the default actions clobber the contents of the pictured  Note that the default actions clobber the contents of the pictured
 numeric output string, so you should not use @code{~~}, e.g., between  numeric output string, so you should not use @code{~~}, e.g., between
Line 1526  doc-~~ Line 1542  doc-~~
 doc-printdebugdata  doc-printdebugdata
 doc-printdebugline  doc-printdebugline
   
 @node  @node Assertions,  , Debugging, Programming Tools
 @subsection Assertions  @subsection Assertions
   
   It is a good idea to make your programs self-checking, in particular, if
   you use an assumption (e.g., that a certain field of a data structure is
   never zero) that may become wrong during maintenance. GForth supports
   assertions for this purpose. They are used like this:
   
   @example
   assert( @var{flag} )
   @end example
   
   The code between @code{assert(} and @code{)} should compute a flag, that
   should be true if everything is alright and false otherwise. It should
   not change anything else on the stack. The overall stack effect of the
   assertion is @code{( -- )}. E.g.
   
   @example
   assert( 1 1 + 2 = ) \ what we learn in school
   assert( dup 0<> ) \ assert that the top of stack is not zero
   assert( false ) \ this code should not be reached
   @end example
   
   The need for assertions is different at different times. During
   debugging, we want more checking, in production we sometimes care more
   for speed. Therefore, assertions can be turned off, i.e., the assertion
   becomes a comment. Depending on the importance of an assertion and the
   time it takes to check it, you may want to turn off some assertions and
   keep others turned on. GForth provides several levels of assertions for
   this purpose:
   
   doc-assert0(
   doc-assert1(
   doc-assert2(
   doc-assert3(
   doc-assert(
   doc-)
   
   @code{Assert(} is the same as @code{assert1(}. The variable
   @code{assert-level} specifies the highest assertions that are turned
   on. I.e., at the default @code{assert-level} of one, @code{assert0(} and
   @code{assert1(} assertions perform checking, while @code{assert2(} and
   @code{assert3(} assertions are treated as comments.
   
   Note that the @code{assert-level} is evaluated at compile-time, not at
   run-time. I.e., you cannot turn assertions on or off at run-time, you
   have to set the @code{assert-level} appropriately before compiling a
   piece of code. You can compile several pieces of code at several
   @code{assert-level}s (e.g., a trusted library at level 1 and newly
   written code at level 3).
   
   doc-assert-level
   
   If an assertion fails, a message compatible with Emacs' compilation mode
   is produced and the execution is aborted (currently with @code{ABORT"}.
   If there is interest, we will introduce a special throw code. But if you
   intend to @code{catch} a specific condition, using @code{throw} is
   probably more appropriate than an assertion).
   
 @node Threading Words,  , Programming Tools, Words  @node Threading Words,  , Programming Tools, Words
 @section Threading Words  @section Threading Words
   
Line 1560  GForth comes with @file{gforth.el}, an i Line 1632  GForth comes with @file{gforth.el}, an i
 @file{forth.el} by Goran Rydqvist (icluded in the TILE package). The  @file{forth.el} by Goran Rydqvist (icluded in the TILE package). The
 improvements are a better (but still not perfect) handling of  improvements are a better (but still not perfect) handling of
 indentation. I have also added comment paragraph filling (@kbd{M-q}),  indentation. I have also added comment paragraph filling (@kbd{M-q}),
 commenting (@kbd{C-x \}) and uncommenting (@kbd{C-x |}) regions and  commenting (@kbd{C-x \}) and uncommenting (@kbd{C-u C-x \}) regions and
 removing debugging tracers (@kbd{C-x ~}). I left the stuff I do not use  removing debugging tracers (@kbd{C-x ~}, @pxref{Debugging}). I left the
 alone, even though some of it only makes sense for TILE. To get a  stuff I do not use alone, even though some of it only makes sense for
 description of these features, enter Forth mode and type @kbd{C-h m}.  TILE. To get a description of these features, enter Forth mode and type
   @kbd{C-h m}.
   
 In addition, GForth supports Emacs quite well: The source code locations  In addition, GForth supports Emacs quite well: The source code locations
 given in error messages, debugging output (from @code{~~}) and failed  given in error messages, debugging output (from @code{~~}) and failed
Line 1631  double numbers. GNU C is available for f Line 1704  double numbers. GNU C is available for f
 unimportant) UNIX machines, VMS, 80386s running MS-DOS, the Amiga, and  unimportant) UNIX machines, VMS, 80386s running MS-DOS, the Amiga, and
 the Atari ST, so a Forth written in GNU C can run on all these  the Atari ST, so a Forth written in GNU C can run on all these
 machines@footnote{Due to Apple's look-and-feel lawsuit it is not  machines@footnote{Due to Apple's look-and-feel lawsuit it is not
 available on the Mac (@pxref{Boycott, , Protect Your Freedom--Fight  available on the Mac (@pxref{Boycott, , Protect Your Freedom---Fight
 ``Look And Feel'', gcc.info, GNU C Manual}).}.  ``Look And Feel'', gcc.info, GNU C Manual}).}.
   
 Writing in a portable language has the reputation of producing code that  Writing in a portable language has the reputation of producing code that

Removed from v.1.4  
changed lines
  Added in v.1.10


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