xBase and Clipper language compatible compiler
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C-API

Name

C-API --  C-functions that allows using C-language along with CLIP.

Function

double              _clip_parnd(ClipMachine * cm,int num)
int                 _clip_parni(ClipMachine * cm,int num)
long                _clip_parnl(ClipMachine * cm,int num)
void                _clip_retnd(ClipMachine * cm,double n)
void                _clip_retni(ClipMachine * cm,int n)
void                _clip_retnl(ClipMachine * cm,long n)

Description

CLIP's C-API is a set of C-functions that allows using C-language along with CLIP. It could be necessary for writing some speed critical functions of your project; for writing "wrappers" for existing 3rd party functions or whole libraries, etc. Besides, learning C-API will help you understand internal structure of CLIP.

C-functions aimed to be used with CLIP (that is, which can be called from some CLIP function, 'exported functions' in further) are in separate C source file(s). This file must include "clip.h", which contains declarations of C-API functions and structures.

Each exported function's name must have prefix 'clip_' and the name itself must be in capital letters. Type of function must be 'int' and it must get one and only parameter of type 'ClipMachine *', which is a pointer to the structure containing context of the current CLIP Virtual Machine.

Exported function should return 0 (zero) if successful, or appropriate error code (those described in error.ch, with 'EG_' prefix).

Example:
/* my.c */
#include <stdio.h>
#include "clip.h"

int clip_MYFUNCTION(ClipMachine *cm)
{
printf("Hello from MyFunction()\n");
return 0;
}
/* end of my.c */

/* test.prg */
MyFunction()
/* end of test.prg */

Compilation:

gcc -c -I${CLIPROOT}/include my.c
clip -eM test.prg my.o

Running:
#./test
Hello from MyFunction
#

Function _CLIP_PARND() 

 _clip_parnd(ClipMachine * cm,int num) --> double

_clip_parnd() retrieves a numeric value passed as a parameter from CLIP and converts it to a double type.

<num>

- position of the parameter in parameters list

Returns :

_clip_parnd() returns the value of the specified parameter as a double type.

See also : _clip_parni() _clip_parnl() _clip_retnd() _clip_stornd()

Example :

 #include "clip.h"
 
 int clip_MYFUNCTION(ClipMachine * cm)
 {
 double num = _clip_parnd(cm,1);
 /* ... */
 return 0;
 }

Function _CLIP_PARNI() 

 _clip_parni(ClipMachine * cm,int num) --> int

_clip_parni() retrieves a numeric value passed as a parameter from CLIP and converts it to an int type.

<num>

- position of the parameter in parameters list

Returns :

_clip_parni() returns the value of the specified parameter as an int type.

See also : _clip_parnd() _clip_parnl() _clip_retni() _clip_storni()

Example :

 #include "clip.h"
 
 int clip_MYFUNCTION(ClipMachine * cm)
 {
 int num = _clip_parni(cm,1);
 /* ... */
 return 0;
 }

Function _CLIP_PARNL() 

 _clip_parnl(ClipMachine * cm,int num) --> long

_clip_parnl() retrieves a numeric value passed as a parameter from CLIP and converts it to a long type.

<num>

- position of the parameter in parameters list

Returns :

_clip_parnl() returns the value of the specified parameter as a long type.

See also : _clip_parni() _clip_parnd() _clip_retnl() _clip_stornl()

Example :

 #include "clip.h"
 
 int clip_MYFUNCTION(ClipMachine * cm)
 {
 long num = _clip_parnl(cm,1);
 /* ... */
 return 0;
 }

Function _CLIP_RETND() 

 _clip_retnd(ClipMachine * cm,double n) --> void

_clip_retnd() posts a numeric value into CLIP's return value area. When your exported function returns control to the calling CLIP program, the posted value becomes the CLIP return value of your exported function.

<n>

- a numeric expression of double type

Returns :

_clip_retnd() has no return value.

See also : _clip_parnd() _clip_retni() _clip_retnl() _clip_stornd()

Example :

 #include "clip.h"
 
 int clip_MYFUNCTION(ClipMachine * cm)
 {
 double n;
 /* ... */
 _clip_retnd(cm,n);
 return 0;
 }

Function _CLIP_RETNI() 

 _clip_retni(ClipMachine * cm,int n) --> void

_clip_retni() posts a numeric value into CLIP's return value area. When your exported function returns control to the calling CLIP program, the posted value becomes the CLIP return value of your exported function.

<n>

- a numeric expression of integer type

Returns :

_clip_retni() has no return value.

See also : _clip_parni() _clip_retnd() _clip_retnl() _clip_storni()

Example :

 #include "clip.h"
 
 int clip_MYFUNCTION(ClipMachine * cm)
 {
 int n;
 /* ... */
 _clip_retni(cm,n);
 return 0;
 }

Function _CLIP_RETNL() 

 _clip_retnl(ClipMachine * cm,long n) --> void

_clip_retnl() posts a numeric value into CLIP's return value area. When your exported function returns control to the calling CLIP program, the posted value becomes the CLIP return value of your exported function.

<n>

- a numeric expression of long type

Returns :

_clip_retnl() has no return value.

See also : _clip_parnl() _clip_retni() _clip_retnd() _clip_stornl()

Example :

 #include "clip.h"
 
 int clip_MYFUNCTION(ClipMachine * cm)
 {
 long n;
 /* ... */
 _clip_retnl(cm,n);
 return 0;
 }

Function _CLIP_STORND() 

Returns :
NIL
Function  _CLIP_STORNI() 
 _clip_storni(ClipMachine * mp, int n, int num, int ind) --> int
Returns :
NIL
Function  _CLIP_STORNL() 
 _clip_stornl(ClipMachine * mp, long n, int num, int ind) --> int
Returns :
NIL
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