Sample user primitives for VA Smalltalk

User primitives are stored in shared libraries. A shared library called sample exists in the samples\primitiv directory. (For example, for Microsoft Windows, the primitiv subdirectory contains sample.dll.) The name of the sample library must be specified in the Smalltalk primitive declarations.

sample.c contains (at least) the following:

#include "esuser.h"

#include <string.h>

EsUserPrimitive(add2Numbers)

{

I_32 i1;

I_32 i2;

U_32 rc;

EsObject retVal;

rc = EsIntegerToI32(EsPrimArgument(1), &i1);

if (rc != EsPrimErrNoError)

EsPrimFail(rc, 1);

rc = EsIntegerToI32(EsPrimArgument(2), &i2);

if (rc != EsPrimErrNoError)

EsPrimFail(rc, 2);

rc = EsI32ToInteger(i1 + i2, &retval);

if (rc != EsPrimErrNoError)

EsPrimFail(rc, EsPrimArgNumNoArg);

EsPrimSucceed(retVal);

}

 

EsUserPrimitive(exampleMakeAString)

{

EsObject result;

U_32 rc;

rc = EsCStringToString("This is a C string", &result);

if (rc != EsPrimErrNoError)

EsPrimFail(rc, EsPrimArgNumNoArg);

EsPrimSucceed(result);

}

#ifdef LINKED_USER_PRIMITIVES

EsDefinePrimitiveTable(samplePrimitiveTable)

EsPrimitiveTableEntry("add2Numbers", add2Numbers)

EsPrimitiveTableEntry("exampleMakeAString", exampleMakeAString)

EsEndPrimitiveTable

#endif

In Smalltalk, add the following methods to UndefinedObject:

add: a and: b

<primitive: 'sample':add2Numbers>

^self primitiveFailed

makeAString

<primitive: 'sample':exampleMakeAString>

^self primitiveFailed

Now evaluate the following in a workspace (the expected result follows the --->):

nil add: 54 and: 7 ---> 61

nil add: 16r7FFFFFFF and: 1 ---> -2147483648 (overflow)

nil add: -1 and: -2 ---> -3

nil add: 1073741823 and: 1 ---> 1073741824 (LargeInteger)

nil add: $a and: 2 ---> walkback "invalid class in argument 1"

nil add: 0 and: 16r100000000 ---> walkback "value out of range in argument 2"

nil makeAString ---> 'This is a C string'