| Passing string array to a DLM [message #33027] |
Fri, 29 November 2002 10:25 |
Randall Skelton
Messages: 169
Registered: October 2000
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Senior Member |
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Hi all,
I've managed to stymie myself with a DLM yet again. In this case, I want
to pass a single dimension string array from IDL into C and return a
corresponding array of indicies. Accordingly from C, I want to be able to
index through this string array calling a C function that processes the
strings in a for-loop. Below is a sample that should segfault for IDL
5.x. My problem is basically that I cannot consistently index through the
strings that are sitting in the argv[0]->value.arr->data pointer. I
assume that this pointer points to the first IDL string structure so it
is cast as (IDL_STRING *). I have tried various ways of sub-scripting and
augmenting the 'strings->s' pointer and can get the next string in a
hit-and-miss way that leaves me to believe I am truly missing something.
Call in IDL as:
a = test_passstrings(['blah', 'blah', 'blacksheep'])
Any ideas?
Thanks and happy thanksgiving :)
Randall
--- START: test.dlm ---
MODULE TEST
DESCRIPTION Testing passing a string array
VERSION 1.0
SOURCE Me
BUILD_DATE November 2002
FUNCTION TEST_PASSSTRINGS 1 1
--- END: test.dlm ---
--- START: test.c ---
/* ANSI */
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <string.h>
/* IDL */
#include "export.h"
/* Message Numbers */
#define TEST_ERROR 0
/* Useful macro */
#define ARRLEN(arr) (sizeof(arr)/sizeof(arr[0]))
extern IDL_MSG_BLOCK msg_block;
extern void TEST_exit_handler(void);
extern int TEST_Startup(void);
extern IDL_VPTR IDL_CDECL
TEST_PassStrings(int argc, IDL_VPTR argv[], char *argk);
/* Globals here */
static char statusBuffer[256]; /* for IDL message passing */
static IDL_MSG_DEF msg_arr[] = {
{ "TEST_Error", "%NError: %s." },
{ "TEST_NOSTRINGARRAY", "%Nstring arrays not allowed %s"},
};
IDL_MSG_BLOCK msg_block;
int IDL_Load(void) {
/* Define the message block */
if (!(msg_block = IDL_MessageDefineBlock("TEST", ARRLEN(msg_arr),
msg_arr))) {
return IDL_FALSE;
}
/* Call the startup function to add the routines to IDL. */
/* Routines */
if (!TEST_Startup()) {
IDL_MessageFromBlock(msg_block, TEST_ERROR,
IDL_MSG_RET, "Unable to initialize TEST interface");
}
return IDL_TRUE;
}
#ifdef __IDLPRE53__
/* FOR IDL < 5.3 */
/* Define the functions */
static IDL_SYSFUN_DEF TEST_functions[] = {
{TEST_PassStrings, "TEST_PASSSTRINGS", 1, 1, 0},
};
#else
/* FOR IDL >= 5.3 */
/* Define the functions */
static IDL_SYSFUN_DEF2 TEST_functions[] = {
{TEST_PassStrings, "TEST_PASSSTRINGS", 1, 1, 0, 0},
};
#endif
/* Startup call when DLM is loaded */
int TEST_Startup(void)
{
/* If IDL is pre-5.3 then change IDL_SysRtnAdd to IDL_AddSystemRoutine,
* (NB: the parameters stay the same) */
#ifdef __IDLPRE53__
/* FOR IDL < 5.3 */
/* Add functions */
if (!IDL_AddSystemRoutine(TEST_functions, TRUE,
ARRLEN(TEST_functions))) {
return IDL_FALSE;
}
#else
/* FOR IDL >= 5.3 */
/* Add functions */
if (!IDL_SysRtnAdd(TEST_functions, TRUE,
ARRLEN(TEST_functions))) {
return IDL_FALSE;
}
#endif
/* Register the error handler */
IDL_ExitRegister(TEST_exit_handler);
return(IDL_TRUE);
}
/* Called when IDL is shutdown */
void TEST_exit_handler(void) {
/* Nothing special to do in this case */
}
/*---------------------------------------------------------- ------------------*/
/* Function: TEST_PassStrings
*
* Purpose: Returns an index associated with the given name.
*
* Called in IDL as:
* index = TEST_PassString('string')
*
* Where:
* string = the field name (IDL_STRING)
* index = returned index number
*
*/
IDL_VPTR IDL_CDECL TEST_PassStrings(int argc, IDL_VPTR argv[], char *argk) {
/* Local */
int i;
IDL_STRING *strings;
IDL_VPTR tmp;
IDL_LONG *lonarr;
IDL_LONG lDim[IDL_MAX_ARRAY_DIM];
long n = 0;
/* Get the field index from IDL */
IDL_ENSURE_SIMPLE(argv[0]);
/* Determine if passed argv is an array */
if (argv[0]->flags & IDL_V_ARR) {
/* ARGV IS AN ARRAY */
/* Ensure we only pass one dimension */
if (argv[0]->value.arr->n_dim > 1) {
sprintf(statusBuffer,"Index cannot exceed one dimension");
IDL_Message(IDL_M_NAMED_GENERIC, IDL_MSG_LONGJMP, statusBuffer);
}
/* Get the number of elements */
n = argv[0]->value.arr->n_elts;
/* Create the output string array */
lDim[0] = n;
lonarr = (IDL_LONG *) IDL_MakeTempArray((int) IDL_TYP_LONG, 1, lDim,
IDL_ARR_INI_NOP, &tmp);
strings = (IDL_STRING *) argv[0]->value.arr->data;
/* ----- PROBLEM IS BELOW ----- */
for (i=0; i<n; i++) printf("Strings[%i]: %s\n", i,
(char *) strings->s + i * sizeof(IDL_STRING));
/* for (i=0; i<n; i++) printf("Strings[%i]: %s\n", i,
(char *) strings->s[i]); */
/* ----- PROBLEM IS ABOVE ----- */
/* Fill the array */
for (i=0; i<n; i++) lonarr[i] = i;
} else {
/* Allocate a scalar long to return */
tmp = IDL_GettmpLong(1);
}
return (tmp);
}
--- END: test.c ---
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