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Newsgroups: comp.lang.postscript
Subject: C macros for reading PostScript binary object format
Date: Mon, 08 Jun 2020 12:03:12 -0700
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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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