Liren Large Software Subsidy 7/07.iso/c/c220/3.ddi/WEITEK/WEITEK.DOC

Text File | 1990-12-16 | 7.5 KB | 233 lines

       Copyright (C) 1990 MetaWare Incorporated.  All Rights Reserved.

                          High C Version 1.7
                        Weitek ABACUS Support
                            December 1990

Table of Contents
-----------------

 1.  Included Files
 2.  Compiling
 3.  Calling Convention
 4.  386|DOS-Extender
 5.  Linking
 6.  stdio.h
 7.  Libraries
 8.  Library Name Space
 9.  Math Errors
 10. Problems


1.  Included Files
------------------

   fbench.c     -- Benchmark example program.
   wstdio.h     -- Modified to assume extern functions do not touch the 1167.
   weitek.doc   -- This document.
   hcwp.lib     -- Weitek transcendental library for Phar Lap.
   weitek.pro   -- A sample profile for enabling pragma 1167 or pragma 3167.
   matherr.c    -- Exception-handling function.


2.  Compiling
-------------

To generate Weitek code, compile your program with driver command-line option
-f3167 or -f1167.  This will:

   * Turn on toggle 3167 or 1167, respectively.
   * Link with library HCWP.LIB.
   * Define the macro __1167 to be 1 (this macro is used
     for conditional preprocessing in stdio.h).

If you do not use the driver, instead do the following:

   * Turn on toggle 3167 or 1167.
   * Link as described below.
   * Either:
        include wstdio.h (found in the Weitek subdirectory of your High C
        distribution) instead of stdio.h
     or:
        #define __1167 1 in your program and include stdio.h.

Please read the Programmer's Guide chapter "Floating-Point Support" for
additional information.


3.  Calling Convention
----------------------

Specify calling-convention attribute _NO_1167 to allow allocation of
variables to ABACUS scratch registers rather than to nonvolatile registers.
_NO_1167 informs the compiler that a function (and any functions that it
calls) does not modify the ABACUS register set.

If a math function such as sin calls no other functions, the compiler
allocates variables to ABACUS scratch registers rather than to nonvolatile
registers if possible, thereby avoiding the save/restore at entry to/exit
from sin.  However, if sin calls another function P, the worst is assumed:
that P modifies the ABACUS scratch registers; and therefore variables are
not so allocated.  The result is that sin has to save and restore the
nonvolatile registers.

However, if you use _NO_1167 to indicate that P does not affect the ABACUS
registers, the compiler can use ABACUS scratch registers.  Or, if P is an
error handler that never returns, the effect on sin is the same: it can
assume the scratch registers are saved across the call to P.

You can use this if a function calls a library error routine that reports
or records an error, and either does not use the ABACUS or never returns.
For instance, sqrt and asin both call fprintf.  Informing the compiler that
fprintf does not touch the ABACUS improves execution speed.  For example,
modifying stdio.h to surround the declaration of fprintf with the following
lines achieves this effect:

   pragma Calling_convention(_DEFAULT_CALLING_CONVENTION | _NO_1167);
   ...
   pragma Calling_convention();

See the Programmer's Guide chapter Interfacing to Other Languages for more
information about calling conventions.


4.  386|DOS-Extender
--------------------

To use the compiler with Phar Lap's 386|DOS-Extender, be sure you have a
version of 386|DOS-Extender that detects the 1167.  The MetaWare Run-Time
Libraries automatically intialize the chip.  Phar Lap has implemented this
since Version 1.1u (Fall 1987).


5.  Linking
-----------

If you do not use the driver to invoke the compiler, you must link your High C
programs with all of the following:

   - the Weitek-supplied run-time library (hcwp.lib)
   - the standard High C run-time emulator library (hce.lib)
   - the non-ANSI functions library (na.lib).

For example:

   386link fbench -lib hcwp hce na


6.  stdio.h
-----------

Header file stdio.h contains code conditioned on #ifdef __1167.  If you
use driver command-line option -f3167 or -f1167, __1167 is automatically
defined.  If you do not use these options, you must provide a definition
for __1167  A modified version of stdio.h called wstdio.h is included for
this purpose in the Weitek subdirectory of the High C distribution.  This
header file contains:

   #define __1167 1

and then:

   #include <stdio.h>

You can use wstdio.h, or just define __1167 and then include stdio.h.


7. Libraries
-------------

The High C run-time math libraries for transcendentals are included in your
High C distribution.  If you use header file math.h, you should include these
libraries in your link before the standard High C libraries.  The libraries
are provided for Phar Lap's environment.

These transcendentals were supplied to MetaWare by Weitek under license.  AS
OF THIS WRITING, printf and scanf have not been modified to use the 1167; they
are awaiting further work.


8. Library Name Space
-----------------------------

Weitek uses names in the transcendental library that are not in the ANSI C
Standard.  Do not use these names if you want to avoid the transcendental
routines:

   _cabs       asin        fmod        rcosh       rsqrt_tb2
   _ccos       atan        log         rcot        rsqrt
   _cexp       atan2       log10       rem         rtan
   _clog       carg_err    pow         rexp        rtanh
   _csin       ceil        racos       rfmod       sin
   _csqrt      cos         rarg1_err   rlog        sinh
   _hypot      cosh        rarg1p_err  rlog10      sqrt_tb
   _mwWTKCPR   cot         rarg2_err   rrem        sqrt_tb1
   acos        cotan_      rarg2p_err  rsin        sqrt_tb2
   arg1_err    dcotan_     rasin       rsincosh_tb sqrt_tb3
   arg1p_err   exp         ratan       rsinh       sqrt
   arg2_err    exp_tb      ratan2      rsqrt_tb    tan
   arg2p_err   floor       rcos        rsqrt_tb1   tanh
   math_err_control

The following functions should not be called directly; these are library
functions that return a floating-point type:

   atof
   difftime
   strtod

There is a way around this.  In general, if you would ordinarily use a non-
Weitek-supported library function F as follows:

   extern double F();
   ...
   double answer = F();

instead, write:

   extern void F_();
   ...
   double answer;
   F_(&answer);

where you compile separately, with the 3167/1167 toggles Off, the following
code:

   extern double F();
   void F_(double *result) { *result = F(); }


9. Math Errors
---------------

You can trap math errors in the Weitek library by modifying matherr.c; source
is included.  matherr.c is in the Weitek libraries; if you provide your own,
you override the library version.


10. Problems
------------

If you think you have discovered a Weitek support problem, send a problem
report to MetaWare Customer Service.  If possible, please send a test case
that demonstrates the problem.

All problem reports must include your serial number and specify which version
of the compiler you are using.  If your sample code exceeds 15 lines, please
send it by diskette to the address below, or by E-mail to:

   uunet!acad!metaware!tech
             -or-
   Internet [e-mail]
             -or-
   INTERNET:[e-mail]

MetaWare Customer Service can be reached at [phone], 8:00 am to 4:30 pm
Monday through Friday.


MetaWare Incorporated
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Santa Cruz, CA 95060-5706
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