EPICS_driver_modules/StreamDevice
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Find byte order at run-time because there is no standard how to do this at compile-time.

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zimoch
2010-06-09 08:03:49 +00:00
parent 93906dd022
commit eae987e7f1
1 changed files with 16 additions and 31 deletions
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47
src/RawFloatConverter.cc
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@ -21,21 +21,7 @@
#include "StreamFormatConverter.h"
#include "StreamError.h"
#ifdef vxWorks
#include "vxWorks.h"
#define __BYTE_ORDER _BYTE_ORDER
#define __LITTLE_ENDIAN _LITTLE_ENDIAN
#define __BIG_ENDIAN _BIG_ENDIAN
#else
// Let's hope all other architectures have endian.h
#include "endian.h"
#endif
#ifndef __BYTE_ORDER
#error define __BYTE_ORDER as __LITTLE_ENDIAN or __BIG_ENDIAN
#endif
#if (__BYTE_ORDER == __LITTLE_ENDIAN || __BYTE_ORDER == __BIG_ENDIAN)
static int endian = 0;
// Raw Float Converter %R
@ -50,6 +36,17 @@ int RawFloatConverter::
parse(const StreamFormat& format, StreamBuffer&,
const char*&, bool)
{
// Find out byte order
if (!endian) {
union {long l; char c [sizeof(long)];} u;
u.l=1;
if (u.c[0]) { endian = 1234;} // little endian
else if (u.c[sizeof(long)-1]) { endian = 4321;} // big endian
else {
error ("Cannot find out byte order for %%R format.\n");
return false;
}
}
// Assume IEEE formats with 4 or 8 bytes (default: 4)
if (format.width==0 || format.width==4 || format.width==8)
return double_format;
@ -77,14 +74,9 @@ printDouble(const StreamFormat& format, StreamBuffer& output, double value)
else
buffer.dval = value;
#if (__BYTE_ORDER == __BIG_ENDIAN)
bool swap = format.flags & alt_flag;
#else
bool swap = !(format.flags & alt_flag);
#endif
if (swap)
if (!(format.flags & alt_flag) ^ (endian == 4321))
{
// swap if byte orders differ
for (n = nbOfBytes-1; n >= 0; n--)
{
output.append(buffer.bytes[n]);
@ -119,14 +111,9 @@ scanDouble(const StreamFormat& format, const char* input, double& value)
return(nbOfBytes); // just skip input
}
#if (__BYTE_ORDER == __BIG_ENDIAN)
bool swap = format.flags & alt_flag;
#else
bool swap = !(format.flags & alt_flag);
#endif
if (swap)
if (!(format.flags & alt_flag) ^ (endian == 4321))
{
// swap if byte orders differ
for (n = nbOfBytes-1, i = 0; n >= 0; n--, i++)
{
buffer.bytes[n] = input[i];
@ -147,5 +134,3 @@ scanDouble(const StreamFormat& format, const char* input, double& value)
}
RegisterConverter (RawFloatConverter, "R");
#endif /* known byte order */