> Not sure it's that simple. Say for example, in the original Pascal
> source
> you have a data structure that includes the two fields:
>
> abc : byte ;
> def : byte ;

Where did "byte" come from?  Pascal does not guarantee a data type named
"byte".  You need to be more specific and define "byte".

> And lets assume that abc is word aligned, and we have two assignments:
>
> abc := 100 ;
> def := 200 ;
>
> When I convert to the 16 bit target using C I would normally convert
> these into: (with "word" defined as "unsigned int", and "or" defined as
> "|")
>
> word abc_def ;
>
> abc_def = (100 << 8) or 200 ;

There is no need for that.  The fields would be defined as C records,
whether packed or not.  The translator would just emit the C assignments.

> likewise, say you have the comparison:
>
> if abc > 50
>
> I would convert this to:
>
> if ((abc >> 8) > 50)
>
> Can your translator really do this?

There is no need to.  Let the C compiler do it.

> Did you write it yourself?

Yes.

To illustrate, here is a simple Pascal program:


program t;

type
  byte = 0..255;

  rec = record     {normal (not packed) record}
    abc: byte;
    def: byte;
    end;

  recpack = packed record  {packed record}
    abc: byte;
    def: byte;
    end;

var
  r: rec;
  p: recpack;

begin
  r.abc := 100;
  r.def := 200;

  p.abc := 100;
  p.def := 200;

  if p.abc > 50 then begin
    p.def := r.abc + p.abc;
    end;
  end.


I edited the target language configuration file and deleted the line
defining the 8 bit C data type "char".  It now thinks the target language
only has 16 and 32 bit integer data types.  The target compiler is
otherwise Microsoft Visual C++ for Win32 systems.  "INT" is a 32 bit
integer and "SHORT" is an 8 bit integer.  Here is the C that was generated
from the above Pascal:


/*****************************
**
**   Start of program T.
*/
typedef unsigned short byte_t;

typedef struct rec_t {
  byte_t abc;
  byte_t def;
  } rec_t;

typedef struct recpack_t {
  unsigned int abc: 8;
  unsigned int def: 8;
  } recpack_t;

__declspec(dllexport) int main (
    int argc,
    char * argv) {

  static recpack_t p;
  static rec_t r;

  /*
  **   Executable code for program T.
  */
  r.abc = 100;
  r.def = 200;
  p.abc = 100;
  p.def = 200;
  if (p.abc > 50) {
    p.def = r.abc + p.abc;
    };
  return 0;
  }


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