Paul Clarke
Diff: lenval.c
- Revision:
- 0:1be76329b246
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/lenval.c Sat Jun 30 13:17:05 2012 +0000
@@ -0,0 +1,190 @@
+/*******************************************************/
+/* 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 );
+ }
+}
+