popenw.c

/*
 * popenw.c
 *
 * popen with writing to pipes for matlab
 * 
 * 2005-11-11 dpwe@ee.columbia.edu  after popen
 * 
 *
 * $Header: /homes/drspeech/src/matlabpopen/RCS/popenw.c,v 1.2 2007/01/14 04:10:18 dpwe Exp $
 */
 
#include    <stdio.h>
#include    <math.h>
#include    <ctype.h>

#include    "mex.h"

#ifndef BIG_ENDIAN
#define BIG_ENDIAN 4321
#endif

#ifndef LITTLE_ENDIAN
#define LITTLE_ENDIAN 1234
#endif

#ifndef BYTE_ORDER
#ifdef  __DARWIN_UNIX03
#define BYTE_ORDER LITTLE_ENDIAN
#else
#define BYTE_ORDER BIG_ENDIAN
#endif
#endif

/* check if flags are working
#if BYTE_ORDER == BIG_ENDIAN
#error "byte order big endian"
#endif

#if BYTE_ORDER == LITTLE_ENDIAN
#error "byte order little endian"
#endif
*/

enum {
    MXPO_INT16BE,
    MXPO_INT16LE,
    MXPO_INT16N,
    MXPO_INT16R,
    MXPO_FLOAT,
    MXPO_DOUBLE,
    MXPO_UINT8,
    MXPO_CHAR,
};

#define FILETABSZ 16
static FILE *filetab[FILETABSZ];
static int filetabix = 0;

int findfreetab() {
    /* find an open slot in the file table */
    int i;
    for (i = 0; i < filetabix; ++i) {
	if ( filetab[i] == NULL ) {
	    /* NULL entries are currently unused */
	    return i;
	}
    }
    if (filetabix < FILETABSZ) {
	i = filetabix;
	/* initialize it */
	filetab[i] = NULL;
	++filetabix;
	return i;
    }
    /* out of space */
    return -1;
}

void
mexFunction(int nlhs, mxArray *plhs[], int nrhs, const mxArray *prhs[])
{
    int 	i, err, len;
    long   	pvl, pvb[16];

    if (nrhs < 1){
	mexPrintf("popenw     Y=popenw(X[,D[,F]])  Open and write an external process\n");
	mexPrintf("           When X is a string, that string is executed as a new process\n");
	mexPrintf("           and Y is returned as a handle (integer) to that stream.\n");
	mexPrintf("           Subsequent calls to popen(Y,D[,F]) with that handle write\n");
	mexPrintf("           the data in D to the the process, converted to binary\n");
	mexPrintf("           according to the format string F (default: big endian int16).\n");
	mexPrintf("           A call with D empty means to close the stream.\n");
	return;
    }
    /* look at the data */
    /* Check to be sure input argument is a string. */
    if ((mxIsChar(prhs[0]))){
	/* first argument is string - opening a new command */
	FILE *f;
	char *cmd;
	int tabix = findfreetab();
	
	if (tabix < 0) {
	    mexErrMsgTxt("Out of file table slots.");
	} else {
	    cmd = mxArrayToString(prhs[0]);
	    /* fprintf(stderr, "cmd=%s\n", cmd); */
	    f = popen(cmd, "w");
	    mxFree(cmd);
	    if ( f == NULL ) {
		mexErrMsgTxt("Error running external command.");
		return;
	    }
	    /* else have a new command path - save the handle */
	    filetab[tabix] = f;
	    /* return the index */
	    if (nlhs > 0) {
		double *pd;
		mxArray *rslt = mxCreateDoubleMatrix(1,1, mxREAL);
		plhs[0] = rslt;
		pd = mxGetPr(rslt);
		*pd = (double)tabix;
	    }
	}
	return;
    }	

    if (nrhs < 2) {
	mexErrMsgTxt("apparently accessing handle, but no D argument");
	return;
    }
    
    /* get the handle */
    {
	int ix, rows, cols, npts, ngot; 
	int fmt = MXPO_INT16BE;
	int sz = 2;
	FILE *f = NULL;
	double *pd;
	char *data;

	if (mxGetN(prhs[0]) == 0) {
	    mexErrMsgTxt("handle argument is empty");
	    return;
	}

	pd = mxGetPr(prhs[0]);
	ix = (int)*pd;
	if (ix < filetabix) {
	    f = filetab[ix];
	}
	if (f == NULL) {
	    mexErrMsgTxt("invalid handle");
	    return;
	}

	/* how many values to write */
	npts = mxGetN(prhs[1]) * mxGetM(prhs[1]); 
	if (npts == 0) {
	    /* close */
	    pclose(f);
	    filetab[ix] = NULL;
	    return;
	}

	/* what is the format? */
	if ( nrhs > 2 ) {
	    char *fmtstr;

	    if (!mxIsChar(prhs[2])) {
		mexErrMsgTxt("format arg must be a string");
		return;
	    }
	    fmtstr = mxArrayToString(prhs[2]);
	    if (strcmp(fmtstr, "int16n")==0 || strcmp(fmtstr, "int16") == 0) {
		fmt = MXPO_INT16N;
	    } else if (strcmp(fmtstr, "int16r")==0) {
		fmt = MXPO_INT16R;
	    } else if (strcmp(fmtstr, "int16be")==0) {
#if BYTE_ORDER == BIG_ENDIAN
		fmt = MXPO_INT16N;
#else
		fmt = MXPO_INT16R;
#endif
	    } else if (strcmp(fmtstr, "int16le")==0) {
#if BYTE_ORDER == BIG_ENDIAN
		fmt = MXPO_INT16R;
#else
		fmt = MXPO_INT16N;
#endif
	    } else if (strcmp(fmtstr, "uint8")==0) {
		fmt = MXPO_UINT8;
		sz = 1;
	    } else if (strcmp(fmtstr, "char")==0) {
		fmt = MXPO_CHAR;
		sz = 1;
	    } else {
		mexErrMsgTxt("unrecognized format");
	    }
            mxFree(fmtstr);
	}

	data = (char *)malloc(sz*npts+1);

	/* format conversion */
	if (sz == 1) {
	    if (mxIsChar(prhs[1])) {
                if (mxGetString(prhs[1], data, npts+1) != 0) {
                    mxErrMsgTxt("Problems copying string data");
                }
            } else {
       	        int i;
       	        double *pd = mxGetPr(prhs[1]);
       	        char *pc = (char *)data;
       	        pd = pd + npts - 1;
       	        pc = pc + npts - 1;
       	        for(i = npts-1; i >= 0; --i) {
       	  	    *pc-- = (char)*pd--;
                }
            }
	} else if (fmt == MXPO_INT16N) {
	    int i;
	    double *pd = mxGetPr(prhs[1]);
	    short *ps = (short *)data;
	    pd = pd + npts - 1;
	    ps = ps + npts - 1;
	    for(i = npts-1; i >= 0; --i) {
		*ps-- = (short)*pd--;
	    }
	} else if (fmt == MXPO_INT16R) {
	    int i;
	    double *pd = mxGetPr(prhs[1]);
	    short *ps = (short *)data;
	    short v;
	    pd = pd + npts - 1;
	    ps = ps + npts - 1;
	    for(i = npts-1; i >= 0; --i) {
		v = (short)*pd--;
		*ps -- = (0xFF & (v >> 8)) + (0xFF00 & (v << 8));
	    }
	} else {
	    mexErrMsgTxt("couldn't handle size");
	}
	
	/* write the data */
	ngot = fwrite(data, sz, npts, f);
	
	free(data);

	/* return # bytes written */
	if (nlhs > 0) {
	    double *pd;
	    mxArray *rslt = mxCreateDoubleMatrix(1,1, mxREAL);
	    plhs[0] = rslt;
	    pd = mxGetPr(rslt);
	    *pd = (double)ngot;
	}

	return;
    }
}