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Add (untested) routines to fetch IEEE single-precision and 

double-precision floating-point numbers, in big-endian and little-endian
format (hopefully there aren't any middle-endian formats; if there are,
we'll have to add them), from a tvbuff, and to return floats (for
single-precision) and doubles (for double-precision).

svn path=/trunk/; revision=5147
This commit is contained in:
Guy Harris 2002-04-12 23:25:24 +00:00
parent f19587347e
commit 661056aac4
2 changed files with 130 additions and 2 deletions
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126
epan/tvbuff.c
View File

@ -9,7 +9,7 @@
* the data of a backing tvbuff, or can be a composite of
* other tvbuffs.
*
* $Id: tvbuff.c,v 1.31 2002/03/06 19:17:05 gram Exp $
* $Id: tvbuff.c,v 1.32 2002/04/12 23:25:24 guy Exp $
*
* Copyright (c) 2000 by Gilbert Ramirez <gram@alumni.rice.edu>
*
@ -1005,6 +1005,71 @@ tvb_get_ntohl(tvbuff_t *tvb, gint offset)
return pntohl(ptr);
}
/*
* Fetches an IEEE single-precision floating-point number, in
* big-endian form, and returns a "float".
*
* XXX - should this be "double", in case there are IEEE single-
* precision numbers that won't fit in some platform's native
* "float" format?
*/
float
tvb_get_ntohieee_float(tvbuff_t *tvb, int offset)
{
/*
* XXX - other non-IEEE boxes that can run UNIX include some
* Crays, and possibly other machines.
*
* It appears that the official Linux port to System/390 and
* zArchitecture uses IEEE format floating point (not a
* huge surprise).
*
* I don't know whether there are any other machines that
* could run Ethereal and that don't use IEEE format.
* As far as I know, all of the main commercial microprocessor
* families on which OSes that support Ethereal can run
* use IEEE format (x86, 68k, SPARC, MIPS, PA-RISC, Alpha,
* IA-64, and so on).
*/
#if defined(vax)
#error "Sorry, you'll have to write code to translate to VAX format"
#else
union {
float f;
guint32 w;
} ieee_fp_union;
ieee_fp_union.w = tvb_get_ntohl(tvb, offset);
return ieee_fp_union.f;
#endif
}
/*
* Fetches an IEEE double-precision floating-point number, in
* big-endian form, and returns a "double".
*/
double
tvb_get_ntohieee_double(tvbuff_t *tvb, int offset)
{
#if defined(vax)
#error "Sorry, you'll have to write code to translate to VAX format"
#else
union {
double d;
guint32 w[2];
} ieee_fp_union;
#ifdef WORDS_BIGENDIAN
ieee_fp_union.w[0] = tvb_get_ntohl(tvb, offset);
ieee_fp_union.w[1] = tvb_get_ntohl(tvb, offset+4);
#else
ieee_fp_union.w[0] = tvb_get_ntohl(tvb, offset+4);
ieee_fp_union.w[1] = tvb_get_ntohl(tvb, offset);
#endif
return ieee_fp_union.d;
#endif
}
guint16
tvb_get_letohs(tvbuff_t *tvb, gint offset)
{
@ -1032,6 +1097,65 @@ tvb_get_letohl(tvbuff_t *tvb, gint offset)
return pletohl(ptr);
}
/*
* Fetches an IEEE single-precision floating-point number, in
* little-endian form, and returns a "float".
*
* XXX - should this be "double", in case there are IEEE single-
* precision numbers that won't fit in some platform's native
* "float" format?
*/
float
tvb_get_letohieee_float(tvbuff_t *tvb, int offset)
{
/*
* XXX - other non-IEEE boxes that can run UNIX include Crays
* and System/3x0 and zArchitecture, although later S/390
* and zArchitecture machines also support IEEE floating
* point; I don't know what the compilers used by Linux
* for S/390 and zArchitecture use - they might have chosen
* to support only machines with IEEE format, and used IEEE
* format to avoid portability headaches.
*/
#if defined(vax)
#error "Sorry, you'll have to write code to translate to VAX format"
#else
union {
float f;
guint32 w;
} ieee_fp_union;
ieee_fp_union.w = tvb_get_letohl(tvb, offset);
return ieee_fp_union.f;
#endif
}
/*
* Fetches an IEEE double-precision floating-point number, in
* little-endian form, and returns a "double".
*/
double
tvb_get_letohieee_double(tvbuff_t *tvb, int offset)
{
#if defined(vax)
#error "Sorry, you'll have to write code to translate to VAX format"
#else
union {
double d;
guint32 w[2];
} ieee_fp_union;
#ifdef WORDS_BIGENDIAN
ieee_fp_union.w[0] = tvb_get_letohl(tvb, offset+4);
ieee_fp_union.w[1] = tvb_get_letohl(tvb, offset);
#else
ieee_fp_union.w[0] = tvb_get_letohl(tvb, offset);
ieee_fp_union.w[1] = tvb_get_letohl(tvb, offset+4);
#endif
return ieee_fp_union.d;
#endif
}
/* Find first occurence of needle in tvbuff, starting at offset. Searches
* at most maxlength number of bytes; if maxlength is -1, searches to
* end of tvbuff.

6
epan/tvbuff.h
View File

@ -9,7 +9,7 @@
* the data of a backing tvbuff, or can be a composite of
* other tvbuffs.
*
* $Id: tvbuff.h,v 1.23 2002/03/06 19:17:06 gram Exp $
* $Id: tvbuff.h,v 1.24 2002/04/12 23:25:24 guy Exp $
*
* Copyright (c) 2000 by Gilbert Ramirez <gram@alumni.rice.edu>
*
@ -230,10 +230,14 @@ extern guint8 tvb_get_guint8(tvbuff_t*, gint offset);
extern guint16 tvb_get_ntohs(tvbuff_t*, gint offset);
extern guint32 tvb_get_ntoh24(tvbuff_t*, gint offset);
extern guint32 tvb_get_ntohl(tvbuff_t*, gint offset);
extern float tvb_get_ntohieee_float(tvbuff_t*, gint offset);
extern double tvb_get_ntohieee_double(tvbuff_t*, gint offset);
extern guint16 tvb_get_letohs(tvbuff_t*, gint offset);
extern guint32 tvb_get_letoh24(tvbuff_t*, gint offset);
extern guint32 tvb_get_letohl(tvbuff_t*, gint offset);
extern float tvb_get_letohieee_float(tvbuff_t*, gint offset);
extern double tvb_get_letohieee_double(tvbuff_t*, gint offset);
/* Returns target for convenience. Does not suffer from possible
* expense of tvb_get_ptr(), since this routine is smart enough