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