As part of TeXnicard, I wrote a set of C macros to read the PostScript
binary object format. I am also including a copy of them here. TeXnicard
is in the public domain, so you can use this for whatever you want to do.

#define TY_NULL 0
#define TY_INT 1
#define TY_REAL 2
#define TY_NAME 3
#define TY_BOOL 4
#define TY_STRING 5
#define TY_ARRAY 9
#define TY_MARK 10

#define obj_float(x) ({ int x__=(x); int t_=obj_type(x__); t_==TY_INT?(float)obj_rawvalue(x__):t_==TY_REAL?obj_ufloat(x__):0; })
#define obj_index(x,y) (obj_rawvalue(x)+(y)*8)
#define obj_int(x) ({ int x__=(x); int t_=obj_type(x__); t_==TY_INT||t_==TY_BOOL?obj_rawvalue(x__):t_==TY_REAL?(int)obj_ufloat(x__):0; })
#define obj_int64(x) ({ int x__=(x); int t_=obj_type(x__); t_==TY_INT||t_==TY_BOOL?obj_rawvalue(x__):t_==TY_REAL?(sqlite3_int64)obj_ufloat(x__):0; })
#define obj_isnum(x) ({ int x__=(x); obj_type(x__)==TY_INT || obj_type(x__)==TY_REAL; })
#define obj_length(x) ({ int x__=(x); (object[x__+2]<<8)|object[x__+3]; }) #define obj_ptr(x) (object+obj_rawvalue(x))
#define obj_rawvalue(x) ({ int y__=(x); (int)((object[y__+4]<<24)|(object[y__+5]<<16)|(object[y__+6]<<8)|object[y__+7]); })
#define obj_tag() (object[1])
#define obj_type(x) (object[x]&127)
#define obj_ufloat(x) ({ union { int i; float f; } f__; f__.i=obj_rawvalue(x); f__.f; }) // see psi/ibnum.h in Ghostscript for an explanation of this bug

You can read the header of the PostScript binary object data to find the
total size of the data; the pointer "object" is of type "unsigned char*"
and points to just after the header.

Note that the above uses "sqlite3_int64" as the 64-bit integer type. If
your program does not use SQLite, then you must change this.

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(But if it has these words, then actually it isn't blank, isn't it?)

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On Monday, June 8, 2020 at 2:03:16 PM UTC-5, ne...@zzo38computer.org.invalid wrote:

As part of TeXnicard, I wrote a set of C macros to read the PostScript
binary object format. I am also including a copy of them here. TeXnicard
is in the public domain, so you can use this for whatever you want to do.

I rewrote these macros as K&R style functions. Modest increase in size but
I find it easier to read this way. I think I got all the types in that
look like they're not int.

#include <stdint.h>

enum { TY_NULL, TY_INT, TY_REAL, TY_NAME, TY_BOOL, TY_STRING, TY_ARRAY = 9, TY_MARK };

float obj_float(object,x)unsigned char *object;{
int t = obj_type(object,x);
return t==TY_INT ? (float)x
: t==TY_REAL ? obj_ufloat(object,x)
: 0;
}

obj_index(object,x,y)unsigned char *object;{
return obj_rawvalue(object,x) + y*8;
}

obj_int(object,x)unsigned char *object;{
int t = obj_type(x);
return t==TY_INT ||
t==TY_BOOL ? obj_rawvalue(object,x)
: t==TY_REAL ? (int)obj_ufloat(x)
: 0;
}

int_64_t obj_int64(object,x)unsigned char *object;{
int t = obj_type(x);
return t==TY_INT ||
t==TY_BOOL ? obj_rawvalue(object,x)
: t==TY_REAL ? (int64_t)obj_ufloat(x)
: 0;
}

obj_isnum(object,x)unsigned char *object;{
return obj_type(x)==TY_INT || obj_type(x)==TY_REAL;
}

obj_length(object,x)unsigned char *object;{
return object[x+2]<<8 | object[x+3];
}

obj_ptr(object,x)unsigned char *object;{
return object + obj_rawvalue(x);
}

obj_rawvalue(object,x)unsigned char *object;{
return object[x+4]<<24 | object[x+5]<<16 | object[x+6]<<8 | object[x+7];
}

obj_tag(object)unsigned char *object;{
return object[1];
}

obj_type(object,x)unsigned char *object;{
return object[x]&127;
}

float obj_ufloat(object,x)unsigned char *object;{
union{ int i; float f; } f;
f.i = obj_rawvalue(object,x);
return f.f;
}

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