/* Copyright (C) 2001-2006 artofcode LLC.
   All Rights Reserved.
  
   This software is provided AS-IS with no warranty, either express or
   implied.

   This software is distributed under license and may not be copied, modified
   or distributed except as expressly authorized under the terms of that
   license.  Refer to licensing information at http://www.artifex.com/
   or contact Artifex Software, Inc.,  7 Mt. Lassen Drive - Suite A-134,
   San Rafael, CA  94903, U.S.A., +1(415)492-9861, for further information.
*/

/* $Id: iutil.c 6651 2006-03-13 16:18:19Z stefan $ */
/* Utilities for Ghostscript interpreter */
#include "math_.h"		/* for fabs */
#include "memory_.h"
#include "string_.h"
#include "ghost.h"
#include "ierrors.h"
#include "gsccode.h"		/* for gxfont.h */
#include "gsmatrix.h"
#include "gsutil.h"
#include "gxfont.h"
#include "strimpl.h"
#include "sstring.h"
#include "idict.h"
#include "imemory.h"
#include "iname.h"
#include "ipacked.h"		/* for array_get */
#include "iutil.h"		/* for checking prototypes */
#include "ivmspace.h"
#include "oper.h"
#include "store.h"

/*
 * By design choice, none of the procedures in this file take a context
 * pointer (i_ctx_p).  Since a number of them require a gs_dual_memory_t
 * for store checking or save bookkeeping, we need to #undef idmemory.
 */
#undef idmemory

/* ------ Object utilities ------ */

/* Define the table of ref type properties. */
const byte ref_type_properties[] = {
    REF_TYPE_PROPERTIES_DATA
};

/* Copy refs from one place to another. */
int
refcpy_to_old(ref * aref, uint index, const ref * from,
	      uint size, gs_dual_memory_t *idmemory, client_name_t cname)
{
    ref *to = aref->value.refs + index;
    int code = refs_check_space(from, size, r_space(aref));

    if (code < 0)
	return code;
    /* We have to worry about aliasing.... */
    if (to <= from || from + size <= to)
	while (size--)
	    ref_assign_old(aref, to, from, cname), to++, from++;
    else
	for (from += size, to += size; size--;)
	    from--, to--, ref_assign_old(aref, to, from, cname);
    return 0;
}
void
refcpy_to_new(ref * to, const ref * from, uint size,
	      gs_dual_memory_t *idmemory)
{
    while (size--)
	ref_assign_new(to, from), to++, from++;
}

/* Fill a new object with nulls. */
void
refset_null_new(ref * to, uint size, uint new_mask)
{
    for (; size--; ++to)
	make_ta(to, t_null, new_mask);
}

/* Compare two objects for equality. */
bool
obj_eq(const gs_memory_t *mem, const ref * pref1, const ref * pref2)
{
    ref nref;

    if (r_type(pref1) != r_type(pref2)) {
	/*
	 * Only a few cases need be considered here:
	 * integer/real (and vice versa), name/string (and vice versa),
	 * arrays, and extended operators.
	 */
	switch (r_type(pref1)) {
	    case t_integer:
		return (r_has_type(pref2, t_real) &&
			pref2->value.realval == pref1->value.intval);
	    case t_real:
		return (r_has_type(pref2, t_integer) &&
			pref2->value.intval == pref1->value.realval);
	    case t_name:
		if (!r_has_type(pref2, t_string))
		    return false;
		name_string_ref(mem, pref1, &nref);
		pref1 = &nref;
		break;
	    case t_string:
		if (!r_has_type(pref2, t_name))
		    return false;
		name_string_ref(mem, pref2, &nref);
		pref2 = &nref;
		break;

		/* differing array types can match if length is 0 */
	    case t_array:
	    case t_mixedarray:
	    case t_shortarray:
		return r_is_array(pref2) &&
		       r_size(pref1) == 0 && r_size(pref2) == 0;
	    default:
		if (r_btype(pref1) != r_btype(pref2))
		    return false;
	}
    }
    /*
     * Now do a type-dependent comparison.  This would be very simple if we
     * always filled in all the bytes of a ref, but we currently don't.
     */
    switch (r_btype(pref1)) {
	case t_array:
	    return ((pref1->value.refs == pref2->value.refs ||
	             r_size(pref1) == 0) &&
		    r_size(pref1) == r_size(pref2));
	case t_mixedarray:
	case t_shortarray:
	    return ((pref1->value.packed == pref2->value.packed ||
	             r_size(pref1) == 0) &&
		    r_size(pref1) == r_size(pref2));
	case t_boolean:
	    return (pref1->value.boolval == pref2->value.boolval);
	case t_dictionary:
	    return (pref1->value.pdict == pref2->value.pdict);
	case t_file:
	    return (pref1->value.pfile == pref2->value.pfile &&
		    r_size(pref1) == r_size(pref2));
	case t_integer:
	    return (pref1->value.intval == pref2->value.intval);
	case t_mark:
	case t_null:
	    return true;
	case t_name:
	    return (pref1->value.pname == pref2->value.pname);
	case t_oparray:
	case t_operator:
	    return (op_index(pref1) == op_index(pref2));
	case t_real:
	    return (pref1->value.realval == pref2->value.realval);
	case t_save:
	    return (pref2->value.saveid == pref1->value.saveid);
	case t_string:
	    return (!bytes_compare(pref1->value.bytes, r_size(pref1),
				   pref2->value.bytes, r_size(pref2)));
	case t_device:
	    return (pref1->value.pdevice == pref2->value.pdevice);
	case t_struct:
	case t_astruct:
	    return (pref1->value.pstruct == pref2->value.pstruct);
	case t_fontID:
	    {	/*
		 * In the Adobe implementations, different scalings of a
		 * font have "equal" FIDs, so we do the same.
		 */
		const gs_font *pfont1 = r_ptr(pref1, gs_font);
		const gs_font *pfont2 = r_ptr(pref2, gs_font);

		while (pfont1->base != pfont1)
		    pfont1 = pfont1->base;
		while (pfont2->base != pfont2)
		    pfont2 = pfont2->base;
		return (pfont1 == pfont2);
	    }
    }
    return false;		/* shouldn't happen! */
}

/* Compare two objects for identity. */
bool
obj_ident_eq(const gs_memory_t *mem, const ref * pref1, const ref * pref2)
{
    if (r_type(pref1) != r_type(pref2))
	return false;
    if (r_has_type(pref1, t_string))
	return (pref1->value.bytes == pref2->value.bytes &&
		r_size(pref1) == r_size(pref2));
    return obj_eq(mem, pref1, pref2);
}

/*
 * Set *pchars and *plen to point to the data of a name or string, and
 * return 0.  If the object isn't a name or string, return e_typecheck.
 * If the object is a string without read access, return e_invalidaccess.
 */
int
obj_string_data(const gs_memory_t *mem, const ref *op, const byte **pchars, uint *plen)
{
    switch (r_type(op)) {
    case t_name: {
	ref nref;

	name_string_ref(mem, op, &nref);
	*pchars = nref.value.bytes;
	*plen = r_size(&nref);
	return 0;
    }
    case t_string:
	check_read(*op);
	*pchars = op->value.bytes;
	*plen = r_size(op);
	return 0;
    default:
	return_error(e_typecheck);
    }
}

/*
 * Create a printable representation of an object, a la cvs and =
 * (full_print = 0), == (full_print = 1), or === (full_print = 2).  Return 0
 * if OK, 1 if the destination wasn't large enough, e_invalidaccess if the
 * object's contents weren't readable.  If the return value is 0 or 1,
 * *prlen contains the amount of data returned.  start_pos is the starting
 * output position -- the first start_pos bytes of output are discarded.
 *
 * The mem argument is only used for getting the type of structures,
 * not for allocating; if it is NULL and full_print != 0, structures will
 * print as --(struct)--.
 *
 * This rather complex API is needed so that a client can call obj_cvp
 * repeatedly to print on a stream, which may require suspending at any
 * point to handle stream callouts.
 */
private void ensure_dot(char *);
int
obj_cvp(const ref * op, byte * str, uint len, uint * prlen,
	int full_print, uint start_pos, const gs_memory_t *mem)
{
    char buf[50];  /* big enough for any float, double, or struct name */
    const byte *data = (const byte *)buf;
    uint size;
    int code;
    ref nref;

    if (full_print) {
	static const char * const type_strings[] = { REF_TYPE_PRINT_STRINGS };

	switch (r_btype(op)) {
	case t_boolean:
	case t_integer:
	    break;
	case t_real: {
	    /*
	     * To get fully accurate output results for IEEE
	     * single-precision floats (24 bits of mantissa), the ANSI %g
	     * default of 6 digits is not enough; 9 are needed.
	     * Unfortunately, using %.9g for floats (as opposed to doubles)
	     * produces unfortunate artifacts such as 0.01 5 mul printing as
	     * 0.049999997.  Therefore, we print using %g, and if the result
	     * isn't accurate enough, print again using %.9g.
	     * Unfortunately, a few PostScript programs 'know' that the
	     * printed representation of floats fits into 6 digits (e.g.,
	     * with cvs).  We resolve this by letting cvs, cvrs, and = do
	     * what the Adobe interpreters appear to do (use %g), and only
	     * produce accurate output for ==, for which there is no
	     * analogue of cvs.  What a hack!
	     */
	    float value = op->value.realval;
	    float scanned;

	    sprintf(buf, "%g", value);
	    sscanf(buf, "%f", &scanned);
	    if (scanned != value)
		sprintf(buf, "%.9g", value);
	    ensure_dot(buf);
	    goto rs;
	}
	case t_operator:
	case t_oparray:  
	    code = obj_cvp(op, (byte *)buf + 2, sizeof(buf) - 4, &size, 0, 0, mem);
	    if (code < 0) 
		return code;
	    buf[0] = buf[1] = buf[size + 2] = buf[size + 3] = '-';
	    size += 4;
	    goto nl;
	case t_name:	 
	    if (r_has_attr(op, a_executable)) {
		code = obj_string_data(mem, op, &data, &size);
		if (code < 0)
		    return code;
		goto nl;
	    }
	    if (start_pos > 0)
		return obj_cvp(op, str, len, prlen, 0, start_pos - 1, mem);
	    if (len < 1)
		return_error(e_rangecheck);
	    code = obj_cvp(op, str + 1, len - 1, prlen, 0, 0, mem);
	    if (code < 0)
		return code;
	    str[0] = '/';
	    ++*prlen;
	    return code;
	case t_null:
	    data = (const byte *)"null";
	    goto rs;
	case t_string:  
	    if (!r_has_attr(op, a_read))
		goto other;
	    size = r_size(op);
	    {
		bool truncate = (full_print == 1 && size > CVP_MAX_STRING);
		stream_cursor_read r;
		stream_cursor_write w;
		uint skip;
		byte *wstr;
		uint len1;
		int status = 1;

		if (start_pos == 0) {
		    if (len < 1)
			return_error(e_rangecheck);
		    str[0] = '(';
		    skip = 0;
		    wstr = str + 1;
		} else {
		    skip = start_pos - 1;
		    wstr = str;
		}
		len1 = len + (str - wstr);
		r.ptr = op->value.const_bytes - 1;
		r.limit = r.ptr + (truncate ? CVP_MAX_STRING : size);
		while (skip && status == 1) {
		    uint written;

		    w.ptr = (byte *)buf - 1;
		    w.limit = w.ptr + min(skip + len1, sizeof(buf));
		    status = s_PSSE_template.process(NULL, &r, &w, false);
		    written = w.ptr - ((byte *)buf - 1);
		    if (written > skip) {
			written -= skip;
			memcpy(wstr, buf + skip, written);
			wstr += written;
			skip = 0;
			break;
		    }
		    skip -= written;
		}
		/*
		 * We can reach here with status == 0 (and skip != 0) if
		 * start_pos lies within the trailing ")" or  "...)".
		 */
		if (status == 0) {
#ifdef DEBUG
		    if (skip > (truncate ? 4 : 1)) {
			return_error(e_Fatal);
		    }
#endif
		}
		w.ptr = wstr - 1;
		w.limit = str - 1 + len;
		if (status == 1)
		    status = s_PSSE_template.process(NULL, &r, &w, false);
		*prlen = w.ptr - (str - 1);
		if (status != 0)
		    return 1;
		if (truncate) {
		    if (len - *prlen < 4 - skip)
			return 1;
		    memcpy(w.ptr + 1, "...)" + skip, 4 - skip);
		    *prlen += 4 - skip;
		} else {
		    if (len - *prlen < 1 - skip)
			return 1;
		    memcpy(w.ptr + 1, ")" + skip, 1 - skip);
		    *prlen += 1 - skip;
		}
	    }
	    return 0;
	case t_astruct:
	case t_struct:    
	    if (r_is_foreign(op)) {
		/* gs_object_type may not work. */
		data = (const byte *)"-foreign-struct-";
		goto rs;
	    }
	    if (!mem) {
		data = (const byte *)"-(struct)-";
		goto rs;
	    }
	    data = (const byte *)
		gs_struct_type_name_string(
		     gs_object_type((gs_memory_t *)mem,
				    (const obj_header_t *)op->value.pstruct));
	    size = strlen((const char *)data);
	    if (size > 4 && !memcmp(data + size - 4, "type", 4))
		size -= 4;
	    if (size > sizeof(buf) - 2)
		return_error(e_rangecheck);
	    buf[0] = '-';
	    memcpy(buf + 1, data, size);
	    buf[size + 1] = '-';
	    size += 2;
	    data = (const byte *)buf;
	    goto nl;
	default:
other:
	    {
		int rtype = r_btype(op);

		if (rtype > countof(type_strings))
		    return_error(e_rangecheck);
		data = (const byte *)type_strings[rtype];
		if (data == 0)
		    return_error(e_rangecheck);
	    }
	    goto rs;
	}
    }	
    /* full_print = 0 */
    switch (r_btype(op)) {
    case t_boolean:
	data = (const byte *)(op->value.boolval ? "true" : "false");
	break;
    case t_integer:
	sprintf(buf, "%ld", op->value.intval);
	break;
    case t_string:
	check_read(*op);
	/* falls through */
    case t_name:
	code = obj_string_data(mem, op, &data, &size);
	if (code < 0)
	    return code;
	goto nl;
    case t_oparray: {
	uint index = op_index(op);
	const op_array_table *opt = op_index_op_array_table(index);

	name_index_ref(mem, opt->nx_table[index - opt->base_index], &nref);
	name_string_ref(mem, &nref, &nref);
	code = obj_string_data(mem, &nref, &data, &size);
	if (code < 0)
	    return code;
	goto nl;
    }
    case t_operator: {
	/* Recover the name from the initialization table. */
	uint index = op_index(op);

	/*
	 * Check the validity of the index.  (An out-of-bounds index
	 * is only possible when examining an invalid object using
	 * the debugger.)
	 */
	if (index > 0 && index < op_def_count) {
	    data = (const byte *)(op_index_def(index)->oname + 1);
	    break;
	}
	/* Internal operator, no name. */
	sprintf(buf, "@0x%lx", (ulong) op->value.opproc);
	break;
    }
    case t_real:
	sprintf(buf, "%g", op->value.realval);
	ensure_dot(buf);
	break;
    default:
	data = (const byte *)"--nostringval--";
    }
rs: size = strlen((const char *)data);
nl: if (size < start_pos)
	return_error(e_rangecheck);
    size -= start_pos;
    *prlen = min(size, len);
    memmove(str, data + start_pos, *prlen);
    return (size > len);
}
/*
 * Make sure the converted form of a real number has a decimal point.  This
 * is needed for compatibility with Adobe (and other) interpreters.
 */
private void
ensure_dot(char *buf)
{
    if (strchr(buf, '.') == NULL) {
	char *ept = strchr(buf, 'e');

	if (ept == NULL)
	    strcat(buf, ".0");
	else {
	    /* Insert the .0 before the exponent.  What a nuisance! */
	    char buf1[30];

	    strcpy(buf1, ept);
	    strcpy(ept, ".0");
	    strcat(ept, buf1);
	}
    }
}

/*
 * Create a printable representation of an object, a la cvs and =.  Return 0
 * if OK, e_rangecheck if the destination wasn't large enough,
 * e_invalidaccess if the object's contents weren't readable.  If pchars !=
 * NULL, then if the object was a string or name, store a pointer to its
 * characters in *pchars even if it was too large; otherwise, set *pchars =
 * str.  In any case, store the length in *prlen.
 */
int
obj_cvs(const gs_memory_t *mem, const ref * op, byte * str, uint len, uint * prlen,
	const byte ** pchars)
{
    int code = obj_cvp(op, str, len, prlen, 0, 0, mem);  /* NB: NULL memptr */

    if (code != 1 && pchars) {
	*pchars = str;
	return code;
    }
    obj_string_data(mem, op, pchars, prlen);
    return gs_note_error(e_rangecheck);
}

/* Find the index of an operator that doesn't have one stored in it. */
ushort
op_find_index(const ref * pref /* t_operator */ )
{
    op_proc_t proc = real_opproc(pref);
    const op_def *const *opp = op_defs_all;
    const op_def *const *opend = opp + (op_def_count / OP_DEFS_MAX_SIZE);

    for (; opp < opend; ++opp) {
	const op_def *def = *opp;

	for (; def->oname != 0; ++def)
	    if (def->proc == proc)
		return (opp - op_defs_all) * OP_DEFS_MAX_SIZE + (def - *opp);
    }
    /* Lookup failed!  This isn't possible.... */
    return 0;
}

/*
 * Convert an operator index to an operator or oparray ref.
 * This is only used for debugging and for 'get' from packed arrays,
 * so it doesn't have to be very fast.
 */
void
op_index_ref(uint index, ref * pref)
{
    const op_array_table *opt;

    if (op_index_is_operator(index)) {
	make_oper(pref, index, op_index_proc(index));
	return;
    }
    opt = op_index_op_array_table(index);
    make_tasv(pref, t_oparray, opt->attrs, index,
	      const_refs, (opt->table.value.const_refs
			   + index - opt->base_index));
}

/* Get an element from an array of some kind. */
/* This is also used to index into Encoding vectors, */
/* the error name vector, etc. */
int
array_get(const gs_memory_t *mem, const ref * aref, long index_long, ref * pref)
{
    if ((ulong)index_long >= r_size(aref))
	return_error(e_rangecheck);
    switch (r_type(aref)) {
	case t_array:
	    {
		const ref *pvalue = aref->value.refs + index_long;

		ref_assign(pref, pvalue);
	    }
	    break;
	case t_mixedarray:
	    {
		const ref_packed *packed = aref->value.packed;
		uint index = (uint)index_long;

		for (; index--;)
		    packed = packed_next(packed);
		packed_get(mem, packed, pref);
	    }
	    break;
	case t_shortarray:
	    {
		const ref_packed *packed = aref->value.packed + index_long;

		packed_get(mem, packed, pref);
	    }
	    break;
	default:
	    return_error(e_typecheck);
    }
    return 0;
}

/* Get an element from a packed array. */
/* (This works for ordinary arrays too.) */
/* Source and destination are allowed to overlap if the source is packed, */
/* or if they are identical. */
void
packed_get(const gs_memory_t *mem, const ref_packed * packed, ref * pref)
{
    const ref_packed elt = *packed;
    uint value = elt & packed_value_mask;

    switch (elt >> r_packed_type_shift) {
	default:		/* (shouldn't happen) */
	    make_null(pref);
	    break;
	case pt_executable_operator:
	    op_index_ref(value, pref);
	    break;
	case pt_integer:
	    make_int(pref, (int)value + packed_min_intval);
	    break;
	case pt_literal_name:
	    name_index_ref(mem, value, pref);
	    break;
	case pt_executable_name:
	    name_index_ref(mem, value, pref);
	    r_set_attrs(pref, a_executable);
	    break;
	case pt_full_ref:
	case pt_full_ref + 1:
	    ref_assign(pref, (const ref *)packed);
    }
}

/* Check to make sure an interval contains no object references */
/* to a space younger than a given one. */
/* Return 0 or e_invalidaccess. */
int
refs_check_space(const ref * bot, uint size, uint space)
{
    for (; size--; bot++)
	store_check_space(space, bot);
    return 0;
}

/* ------ String utilities ------ */

/* Convert a C string to a Ghostscript string */
int
string_to_ref(const char *cstr, ref * pref, gs_ref_memory_t * mem,
	      client_name_t cname)
{
    uint size = strlen(cstr);
    int code = gs_alloc_string_ref(mem, pref, a_all, size, cname);

    if (code < 0)
	return code;
    memcpy(pref->value.bytes, cstr, size);
    return 0;
}

/* Convert a Ghostscript string to a C string. */
/* Return 0 iff the buffer can't be allocated. */
char *
ref_to_string(const ref * pref, gs_memory_t * mem, client_name_t cname)
{
    uint size = r_size(pref);
    char *str = (char *)gs_alloc_string(mem, size + 1, cname);

    if (str == 0)
	return 0;
    memcpy(str, (const char *)pref->value.bytes, size);
    str[size] = 0;
    return str;
}

/* ------ Operand utilities ------ */

/* Get N numeric operands from the stack or an array. */
/* Return a bit-mask indicating which ones are integers, */
/* or a (negative) error indication. */
/* The 1-bit in the bit-mask refers to the first operand. */
/* Store float versions of the operands at pval. */
/* The stack underflow check (check for t__invalid) is harmless */
/* if the operands come from somewhere other than the stack. */
int
num_params(const ref * op, int count, double *pval)
{
    int mask = 0;

    pval += count;
    while (--count >= 0) {
	mask <<= 1;
	switch (r_type(op)) {
	    case t_real:
		*--pval = op->value.realval;
		break;
	    case t_integer:
		*--pval = op->value.intval;
		mask++;
		break;
	    case t__invalid:
		return_error(e_stackunderflow);
	    default:
		return_error(e_typecheck);
	}
	op--;
    }
    /* If count is very large, mask might overflow. */
    /* In this case we clearly don't care about the value of mask. */
    return (mask < 0 ? 0 : mask);
}
/* float_params doesn't bother to keep track of the mask. */
int
float_params(const ref * op, int count, float *pval)
{
    for (pval += count; --count >= 0; --op)
	switch (r_type(op)) {
	    case t_real:
		*--pval = op->value.realval;
		break;
	    case t_integer:
		*--pval = (float)op->value.intval;
		break;
	    case t__invalid:
		return_error(e_stackunderflow);
	    default:
		return_error(e_typecheck);
	}
    return 0;
}

/* Get N numeric parameters (as floating point numbers) from an array */
int
process_float_array(const gs_memory_t *mem, const ref * parray, int count, float * pval)
{
    int         code = 0, indx0 = 0;

    /* we assume parray is an array of some type, of adequate length */
    if (r_has_type(parray, t_array))
        return float_params(parray->value.refs + count - 1, count, pval);

    /* short/mixed array; convert the entries to refs */
    while (count > 0 && code >= 0) {
        int     i, subcount;
        ref     ref_buff[20];   /* 20 is arbitrary */

        subcount = (count > countof(ref_buff) ? countof(ref_buff) : count);
        for (i = 0; i < subcount && code >= 0; i++)
            code = array_get(mem, parray, (long)(i + indx0), &ref_buff[i]);
        if (code >= 0)
            code = float_params(ref_buff + subcount - 1, subcount, pval);
        count -= subcount;
        pval += subcount;
        indx0 += subcount;
    }

    return code;
}

/* Get a single real parameter. */
/* The only possible error is e_typecheck. */
/* If an error is returned, the return value is not updated. */
int
real_param(const ref * op, double *pparam)
{
    switch (r_type(op)) {
	case t_integer:
	    *pparam = op->value.intval;
	    break;
	case t_real:
	    *pparam = op->value.realval;
	    break;
	default:
	    return_error(e_typecheck);
    }
    return 0;
}
int
float_param(const ref * op, float *pparam)
{
    double dval;
    int code = real_param(op, &dval);

    if (code >= 0)
	*pparam = (float)dval;	/* can't overflow */
    return code;
}

/* Get an integer parameter in a given range. */
int
int_param(const ref * op, int max_value, int *pparam)
{
    check_int_leu(*op, max_value);
    *pparam = (int)op->value.intval;
    return 0;
}

/* Make real values on the operand stack. */
int
make_reals(ref * op, const double *pval, int count)
{
    /* This should return e_limitcheck if any real is too large */
    /* to fit into a float on the stack. */
    for (; count--; op++, pval++)
	make_real(op, *pval);
    return 0;
}
int
make_floats(ref * op, const float *pval, int count)
{
    /* This should return e_undefinedresult for infinities. */
    for (; count--; op++, pval++)
	make_real(op, *pval);
    return 0;
}

/* Compute the error code when check_proc fails. */
/* Note that the client, not this procedure, uses return_error. */
/* The stack underflow check is harmless in the off-stack case. */
int
check_proc_failed(const ref * pref)
{
    return (r_is_array(pref) ? e_invalidaccess :
	    r_has_type(pref, t__invalid) ? e_stackunderflow :
	    e_typecheck);
}

/* Compute the error code when a type check on the stack fails. */
/* Note that the client, not this procedure, uses return_error. */
int
check_type_failed(const ref * op)
{
    return (r_has_type(op, t__invalid) ? e_stackunderflow : e_typecheck);
}

/* ------ Matrix utilities ------ */

/* Read a matrix operand. */
/* Return 0 if OK, error code if not. */
int
read_matrix(const gs_memory_t *mem, const ref * op, gs_matrix * pmat)
{
    int code;
    ref values[6];
    const ref *pvalues;

    if (r_has_type(op, t_array))
	pvalues = op->value.refs;
    else {
	int i;

	for (i = 0; i < 6; ++i) {
	    code = array_get(mem, op, (long)i, &values[i]);
	    if (code < 0)
		return code;
	}
	pvalues = values;
    }
    check_read(*op);
    if (r_size(op) != 6)
	return_error(e_rangecheck);
    code = float_params(pvalues + 5, 6, (float *)pmat);
    return (code < 0 ? code : 0);
}

/* Write a matrix operand. */
/* Return 0 if OK, error code if not. */
int
write_matrix_in(ref * op, const gs_matrix * pmat, gs_dual_memory_t *idmemory,
		gs_ref_memory_t *imem)
{
    ref *aptr;
    const float *pel;
    int i;

    check_write_type(*op, t_array);
    if (r_size(op) != 6)
	return_error(e_rangecheck);
    aptr = op->value.refs;
    pel = (const float *)pmat;
    for (i = 5; i >= 0; i--, aptr++, pel++) {
	if (idmemory) {
	    ref_save(op, aptr, "write_matrix");
	    make_real_new(aptr, *pel);
	} else {
	    make_tav(aptr, t_real, imemory_new_mask(imem), realval, *pel);
	}
    }
    return 0;
}
