dioscuri.module.cpu
Class Util

java.lang.Object
  dioscuri.module.cpu.Util

public class Util
extends java.lang.Object

Author:

Bram Lohman, Bart Kiers

Field Summary

protected static boolean	cf
protected static int	lowerByteCarry

Method Summary

protected static byte[]	addRegRegDisp(byte[] reg1, byte[] reg2, byte[] displacement) Adds two registers and the memory reference displacement. Does not check carry or overflow flags.
protected static byte[]	addWords(byte[] word1, byte[] word2, int carryBit) Adds two words (16-bit) including a possible carry bit. Takes care of possible carry from LSB to MSB.
protected static byte[]	booleansToBytes(boolean[] booleans) Converts a boolean[] into a byte[] Each boolean value is converted into a hexadecimal (0 or 1) value and placed in a byte[].
protected static boolean[]	bytesToBooleans(byte[] bytes) Converts a byte[] into a boolean[] Each bit is converted into a boolean value and placed in a boolean[].
protected static boolean	checkParityOfByte(byte data) Check the parity of a given byte and given size in bits.
protected static java.lang.String	convertByteToString(byte b)
protected static byte	convertStringToByte(java.lang.String strValue) Converts a given string into a byte of one integer
protected static byte[]	convertStringToWord(java.lang.String strValue) Converts a given string into a word of bytes
protected static java.lang.String	convertWordToString(byte[] word)
static int	getExponent(double val)
static int	getExponent(float val)
static double	scalb(double d, int i)
static float	scalb(float f, int i)
protected static byte	signExtend(byte inputByte) Determines the sign of the input byte and returns the complementary (sign-extended) byte
protected static byte[]	subtractWords(byte[] word1, byte[] word2, int borrowBit) Subtracts two words (16-bit) including a possible borrow bit. Takes care of possible borrow from LSB to MSB.
protected static boolean	test_AF_ADD(byte input, byte result) Test the auxiliary flag (AF) for addition with possible carry. AF is set when carry occurs to higher nibble.
protected static boolean	test_AF_ShiftLeft(byte input, int shifts) Test the auxiliary flag (AF) for shift operations with byte. AF is set when carry occurs.
protected static boolean	test_AF_SUB(byte input, byte result) Test the auxiliary flag (AF) for subtraction with possible borrow. AF is set when borrow occurs from higher nibble.
protected static boolean	test_CF_ADD(byte[] input1, byte[] input2, int carry) Test the carry flag for addition operations with words. CF is set when unsigned overflow occurs.
protected static boolean	test_CF_ADD(byte input1, byte input2, int carry) Test the carry flag for addition operations with bytes. CF is set when unsigned overflow occurs.
protected static boolean	test_CF_SUB(byte[] input1, byte[] input2, int carry) Test the carry flag for subtraction operations with words. CF is set when unsigned overflow occurs.
protected static boolean	test_CF_SUB(byte input1, byte input2, int carry) Test the carry flag for subtraction operations with bytes. CF is set when unsigned overflow occurs.
protected static boolean	test_OF_ADD(byte[] input1, byte[] input2, byte[] result, int carry) Test the overflow flag for addition operations with words. OF is set when 2's complement signed overflow occur.
protected static boolean	test_OF_ADD(byte input1, byte input2, byte result, int carry) Test the overflow flag for addition operations with bytes. OF is set when 2's complement signed overflow occur.
protected static boolean	test_OF_SUB(byte[] input1, byte[] input2, byte[] result, int carry) Test the overflow flag for subtraction operations with words. OF is set when 2's complement signed overflow occurs.
protected static boolean	test_OF_SUB(byte input1, byte input2, byte result, int carry) Test the overflow flag for subtraction operations with bytes. OF is set when 2's complement signed overflow occurs.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

cf

protected static boolean cf

lowerByteCarry

protected static int lowerByteCarry

Method Detail

checkParityOfByte

protected static boolean checkParityOfByte(byte data)

Check the parity of a given byte and given size in bits.

Parameters:

data -

Returns:

-

addWords

protected static byte[] addWords(byte[] word1,
                                 byte[] word2,
                                 int carryBit)

Adds two words (16-bit) including a possible carry bit.
Takes care of possible carry from LSB to MSB. Not beyond MSB. Does not care about signed/unsigned as this doesn't effect the actual result in hex.

Parameters:

word1 - first word

word2 - second word

carryBit -

Returns:

sum of both words including possible carry between LSB and MSB

subtractWords

protected static byte[] subtractWords(byte[] word1,
                                      byte[] word2,
                                      int borrowBit)

Subtracts two words (16-bit) including a possible borrow bit.
Takes care of possible borrow from LSB to MSB. Not beyond MSB. Does not care about signed/unsigned as this doesn't effect the actual result in hex. Operation: word1 - (word2 + borrow)

Parameters:

word1 - first word

word2 - second word

borrowBit -

Returns:

subtraction of both words plus borrow including possible borrow between LSB and MSB

addRegRegDisp

protected static byte[] addRegRegDisp(byte[] reg1,
                                      byte[] reg2,
                                      byte[] displacement)

Adds two registers and the memory reference displacement.
Does not check carry or overflow flags.

Parameters:

reg1 - first register to be added

reg2 - second register to be added

displacement -

Returns:

sum of both registers and memory displacement

test_AF_ADD

protected static boolean test_AF_ADD(byte input,
                                     byte result)

Test the auxiliary flag (AF) for addition with possible carry.
AF is set when carry occurs to higher nibble.

Parameters:

input -

result -

Returns:

true if carry occurs, false otherwise

test_AF_SUB

protected static boolean test_AF_SUB(byte input,
                                     byte result)

Test the auxiliary flag (AF) for subtraction with possible borrow.
AF is set when borrow occurs from higher nibble.

Parameters:

input -

result -

Returns:

true if borrow occurs, false otherwise

test_AF_ShiftLeft

protected static boolean test_AF_ShiftLeft(byte input,
                                           int shifts)

Test the auxiliary flag (AF) for shift operations with byte.
AF is set when carry occurs. This happens when last shift causes a carry out of lowest nibble

Parameters:

input -

shifts -

Returns:

true if carry/borrow occurs, false otherwise

test_CF_ADD

protected static boolean test_CF_ADD(byte input1,
                                     byte input2,
                                     int carry)

Test the carry flag for addition operations with bytes.
CF is set when unsigned overflow occurs. This happens when we cross over from 255 to 0 while adding or cross over from 0 to 255 while subtracting. The operation is (input1 + carry) + input2

Parameters:

input1 -

input2 -

carry -

Returns:

true if carry occurs, false otherwise

test_CF_ADD

protected static boolean test_CF_ADD(byte[] input1,
                                     byte[] input2,
                                     int carry)

Test the carry flag for addition operations with words.
CF is set when unsigned overflow occurs. This happens when we cross over from 65535 (0xFFFF) to 0 while adding or cross over from 0 to 65535 (0xFFFF) while subtracting. The operation is (input1 + carry) + input2

Parameters:

input1 -

input2 -

carry -

Returns:

true if carry occurs, false otherwise

test_CF_SUB

protected static boolean test_CF_SUB(byte input1,
                                     byte input2,
                                     int carry)

Test the carry flag for subtraction operations with bytes.
CF is set when unsigned overflow occurs. This happens when we cross over from 255 to 0 while adding or cross over from 0 to 255 while subtracting. The operation is input1 - (input2 + carry)

Parameters:

input1 - unsigned input1 of operation

input2 - unsigned input2 of operation

carry - possible carry bit

Returns:

true if borrow occurs, false otherwise

test_CF_SUB

protected static boolean test_CF_SUB(byte[] input1,
                                     byte[] input2,
                                     int carry)

Test the carry flag for subtraction operations with words.
CF is set when unsigned overflow occurs. This happens when we cross over from 255 to 0 while adding or cross over from 0 to 255 while subtracting. The operation is input1 - (input2 + carry)

Parameters:

input1 -

input2 -

carry -

Returns:

true if borrow occurs, false otherwise

test_OF_ADD

protected static boolean test_OF_ADD(byte input1,
                                     byte input2,
                                     byte result,
                                     int carry)

Test the overflow flag for addition operations with bytes.
OF is set when 2's complement signed overflow occur. This happens when we cross over from 127 to -128 while adding or cross over from -128 to 127 while subtracting.

Parameters:

input1 -

input2 -

result -

carry -

Returns:

true if overflow occurs, false otherwise

test_OF_ADD

protected static boolean test_OF_ADD(byte[] input1,
                                     byte[] input2,
                                     byte[] result,
                                     int carry)

Test the overflow flag for addition operations with words.
OF is set when 2's complement signed overflow occur. This happens when we cross over from 32767 (0x7FFF) to -32768 (0x8000) while adding or cross over from -32768 to 32767 while subtracting.

Parameters:

input1 -

result -

input2 -

carry -

Returns:

true if overflow occurs, false otherwise

test_OF_SUB

protected static boolean test_OF_SUB(byte input1,
                                     byte input2,
                                     byte result,
                                     int carry)

Test the overflow flag for subtraction operations with bytes.
OF is set when 2's complement signed overflow occurs. This happens when we cross over from 127 to -128 while adding or cross over from -128 to 127 while subtracting.

Parameters:

input1 -

input2 -

carry -

result -

Returns:

true if overflow occurs, false otherwise

test_OF_SUB

protected static boolean test_OF_SUB(byte[] input1,
                                     byte[] input2,
                                     byte[] result,
                                     int carry)

Test the overflow flag for subtraction operations with words.
OF is set when 2's complement signed overflow occurs. This happens when we cross over from 32767 (0x7FFF) to -32768 (0x8000) while adding or cross over from -32768 to 32767 while subtracting.

Parameters:

input1 -

input2 -

result -

carry -

Returns:

true if overflow occurs, false otherwise

signExtend

protected static byte signExtend(byte inputByte)

Determines the sign of the input byte and returns the complementary (sign-extended) byte

Parameters:

inputByte - Byte whose sign determines value of sign-extension

Returns:

Byte of value 0x00 if no sign, 0xFF if signed

booleansToBytes

protected static byte[] booleansToBytes(boolean[] booleans)

Converts a boolean[] into a byte[] Each boolean value is converted into a hexadecimal (0 or 1) value and placed in a byte[]. Note: boolean[] must be of multiple of 8 booleans.

Parameters:

booleans -

Returns:

byte[] containing the converted booleans

bytesToBooleans

protected static boolean[] bytesToBooleans(byte[] bytes)

Converts a byte[] into a boolean[] Each bit is converted into a boolean value and placed in a boolean[].

Parameters:

bytes -

Returns:

boolean[] containing the converted bytes

convertByteToString

protected static java.lang.String convertByteToString(byte b)

Parameters:

b -

Returns:

-

convertWordToString

protected static java.lang.String convertWordToString(byte[] word)

Parameters:

word -

Returns:

-

convertStringToByte

protected static byte convertStringToByte(java.lang.String strValue)

Converts a given string into a byte of one integer

Parameters:

strValue -

Returns:

int as byte

convertStringToWord

protected static byte[] convertStringToWord(java.lang.String strValue)

Converts a given string into a word of bytes

Parameters:

strValue -

Returns:

byte[] as word

getExponent

public static int getExponent(double val)

Parameters:

val -

Returns:

-

getExponent

public static int getExponent(float val)

Parameters:

val -

Returns:

-

scalb

public static double scalb(double d,
                           int i)

Parameters:

d -

i -

Returns:

-

scalb

public static float scalb(float f,
                          int i)

Parameters:

f -

i -

Returns:

-