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lenval.cpp
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lenval.cpp
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/*******************************************************/
/* file: lenval.c */
/* abstract: This file contains routines for using */
/* the lenVal data structure. */
/*******************************************************/
#include "lenval.h"
#include "ports.h"
/*****************************************************************************
* Function: value
* Description: Extract the long value from the lenval array.
* Parameters: plvValue - ptr to lenval.
* Returns: long - the extracted value.
*****************************************************************************/
long value( lenVal* plvValue )
{
long lValue; /* result to hold the accumulated result */
short sIndex;
lValue = 0;
for ( sIndex = 0; sIndex < plvValue->len ; ++sIndex )
{
lValue <<= 8; /* shift the accumulated result */
lValue |= plvValue->val[ sIndex]; /* get the last byte first */
}
return( lValue );
}
/*****************************************************************************
* Function: initLenVal
* Description: Initialize the lenval array with the given value.
* Assumes lValue is less than 256.
* Parameters: plv - ptr to lenval.
* lValue - the value to set.
* Returns: void.
*****************************************************************************/
void initLenVal( lenVal* plv,
long lValue )
{
plv->len = 1;
plv->val[0] = (unsigned char)lValue;
}
/*****************************************************************************
* Function: EqualLenVal
* Description: Compare two lenval arrays with an optional mask.
* Parameters: plvTdoExpected - ptr to lenval #1.
* plvTdoCaptured - ptr to lenval #2.
* plvTdoMask - optional ptr to mask (=0 if no mask).
* Returns: short - 0 = mismatch; 1 = equal.
*****************************************************************************/
short EqualLenVal( lenVal* plvTdoExpected,
lenVal* plvTdoCaptured,
lenVal* plvTdoMask )
{
short sEqual;
short sIndex;
unsigned char ucByteVal1;
unsigned char ucByteVal2;
unsigned char ucByteMask;
sEqual = 1;
sIndex = plvTdoExpected->len;
while ( sEqual && sIndex-- )
{
ucByteVal1 = plvTdoExpected->val[ sIndex ];
ucByteVal2 = plvTdoCaptured->val[ sIndex ];
if ( plvTdoMask )
{
ucByteMask = plvTdoMask->val[ sIndex ];
ucByteVal1 &= ucByteMask;
ucByteVal2 &= ucByteMask;
}
if ( ucByteVal1 != ucByteVal2 )
{
sEqual = 0;
}
}
return( sEqual );
}
/*****************************************************************************
* Function: RetBit
* Description: return the (byte, bit) of lv (reading from left to right).
* Parameters: plv - ptr to lenval.
* iByte - the byte to get the bit from.
* iBit - the bit number (0=msb)
* Returns: short - the bit value.
*****************************************************************************/
short RetBit( lenVal* plv,
int iByte,
int iBit )
{
/* assert( ( iByte >= 0 ) && ( iByte < plv->len ) ); */
/* assert( ( iBit >= 0 ) && ( iBit < 8 ) ); */
return( (short)( ( plv->val[ iByte ] >> ( 7 - iBit ) ) & 0x1 ) );
}
/*****************************************************************************
* Function: SetBit
* Description: set the (byte, bit) of lv equal to val
* Example: SetBit("00000000",byte, 1) equals "01000000".
* Parameters: plv - ptr to lenval.
* iByte - the byte to get the bit from.
* iBit - the bit number (0=msb).
* sVal - the bit value to set.
* Returns: void.
*****************************************************************************/
void SetBit( lenVal* plv,
int iByte,
int iBit,
short sVal )
{
unsigned char ucByteVal;
unsigned char ucBitMask;
ucBitMask = (unsigned char)(1 << ( 7 - iBit ));
ucByteVal = (unsigned char)(plv->val[ iByte ] & (~ucBitMask));
if ( sVal )
{
ucByteVal |= ucBitMask;
}
plv->val[ iByte ] = ucByteVal;
}
/*****************************************************************************
* Function: AddVal
* Description: add val1 to val2 and store in resVal;
* assumes val1 and val2 are of equal length.
* Parameters: plvResVal - ptr to result.
* plvVal1 - ptr of addendum.
* plvVal2 - ptr of addendum.
* Returns: void.
*****************************************************************************/
void addVal( lenVal* plvResVal,
lenVal* plvVal1,
lenVal* plvVal2 )
{
unsigned char ucCarry;
unsigned short usSum;
unsigned short usVal1;
unsigned short usVal2;
short sIndex;
plvResVal->len = plvVal1->len; /* set up length of result */
/* start at least significant bit and add bytes */
ucCarry = 0;
sIndex = plvVal1->len;
while ( sIndex-- )
{
usVal1 = plvVal1->val[ sIndex ]; /* i'th byte of val1 */
usVal2 = plvVal2->val[ sIndex ]; /* i'th byte of val2 */
/* add the two bytes plus carry from previous addition */
usSum = (unsigned short)( usVal1 + usVal2 + ucCarry );
/* set up carry for next byte */
ucCarry = (unsigned char)( ( usSum > 255 ) ? 1 : 0 );
/* set the i'th byte of the result */
plvResVal->val[ sIndex ] = (unsigned char)usSum;
}
}
/*****************************************************************************
* Function: readVal
* Description: read from XSVF numBytes bytes of data into x.
* Parameters: plv - ptr to lenval in which to put the bytes read.
* sNumBytes - the number of bytes to read.
* Returns: void.
*****************************************************************************/
void readVal( lenVal* plv,
short sNumBytes )
{
unsigned char* pucVal;
plv->len = sNumBytes; /* set the length of the lenVal */
for ( pucVal = plv->val; sNumBytes; --sNumBytes, ++pucVal )
{
/* read a byte of data into the lenVal */
readByte( pucVal );
}
}