io.dvlopt.linux.i2c.I2CBlock Maven / Gradle / Ivy
/*
* Copyright 2018 Adam Helinski
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package io.dvlopt.linux.i2c ;
import com.sun.jna.Memory ;
import io.dvlopt.linux.NativeMemory ;
import io.dvlopt.linux.i2c.internal.NativeI2CSmbusData ;
/**
* Class representing a block of bytes for SMBUS operations.
*
* Such a buffer is limited to 32 bytes.
*/
public class I2CBlock {
/**
* The length of a buffer.
*/
public static final int SIZE = NativeI2CSmbusData.SIZE - 2 ;
private int length ;
final Memory memory ;
/**
* Allocates a block.
*/
public I2CBlock() {
this.memory = new Memory( NativeI2CSmbusData.SIZE + 1 ) ;
this.memory.clear() ;
}
/**
* Fills the block with 0.
*
* @return This instance.
*/
public I2CBlock clear() {
this.memory.clear() ;
this.length = 0 ;
return this ;
}
/**
* Retrieves the current length of this block.
*
* Setting a byte to an index adjusts the length of the block to the
* highest index.
*
* @return The length.
*
* @see #set( int, int )
*/
public int length() {
return this.length ;
}
// Retrieves and syncs the length set by a native SMBUS call.
//
int readLength() {
this.length = NativeMemory.getUnsignedByte( this.memory ,
0 ) ;
return this.length ;
}
// Syncs the length for a native SMBUS call.
//
void writeLength() {
this.writeLength( this.length ) ;
}
// Writes and syncs the length for a native SMBUS call.
//
void writeLength( int length ) {
NativeMemory.setUnsignedByte( this.memory ,
0 ,
length ) ;
this.length = length ;
}
/**
* Retrieves the byte at the given position.
*
* @param index Where.
*
* @return An unsigned byte.
*/
public int get( int index ) {
return NativeMemory.getUnsignedByte( this.memory ,
index + 1 ) ;
}
/**
* Sets the byte at the given position.
*
* The length of this block will be adjusted to reflect the highest index
* of a byte set by the user or by an SMBUS operation.
*
* @param index Which one.
*
* @param b An unsigned byte.
*
* @return This instance.
*/
public I2CBlock set( int index ,
int b ) {
index += 1 ;
NativeMemory.setUnsignedByte( this.memory ,
index ,
b ) ;
this.length = Math.max( this.length ,
index ) ;
return this ;
}
}