private void STEP2(int A, int B, int MAC, int MIC, short[] LAR, int index) {
short temp = 0;
temp = Add.GSM_MULT((short) A, LAR[index]);
temp = Add.GSM_ADD(temp, (short) B);
temp = Add.GSM_ADD(temp, (short) 256);
temp = Add.SASR(temp, 9);
LAR[index] = (short) (temp > MAC ? MAC - MIC : (temp < MIC ? 0 : temp - MIC));
}
private void Reflection_coefficients(short[] r /* 0...7 OUT */)
throws IllegalArgumentException {
short temp = 0;
int ltmp = 0;
int r_index = 0;
short[] ACF = new short[9]; /* 0..8 */
short[] P = new short[9]; /* 0..8 */
short[] K = new short[9]; /* 2..8 */
/* Schur recursion with 16 bits arithmetic.
*/
if (L_ACF[0] == 0) {
/* everything is the same. */
for (int i = 0; i < 8; i++) {
r[i] = 0;
}
return;
}
if (L_ACF[0] == 0) {
throw new IllegalArgumentException(
"Reflection_coefficients: L_ACF[0] = " + L_ACF[0] + " should not = 0.");
}
temp = Add.gsm_norm(L_ACF[0]);
if (!(temp >= 0 && temp < 32)) {
throw new IllegalArgumentException(
"Reflection_coefficients: temp = " + temp + " should be >= 0 and < 32.");
}
/* ? overflow ? */
for (int i = 0; i <= 8; i++) {
ACF[i] = Add.SASR(L_ACF[i] << temp, 16);
}
/* Initialize array P[..] and K[..] for the recursion.
*/
System.arraycopy(ACF, 0, K, 0, 7);
System.arraycopy(ACF, 0, P, 0, 8);
/* CoreCompute reflection coefficients
*/
for (int n = 1; n <= 8; n++, r_index++) {
temp = P[1];
temp = Add.GSM_ABS(temp);
if (P[0] < temp) {
for (int i = n; i < 8; i++) {
r[i] = 0;
}
return;
}
r[r_index] = Add.gsm_div(temp, P[0]);
if (!(r[r_index] >= 0)) {
throw new IllegalArgumentException(
"Reflection_coefficients: r[" + r_index + "] = " + r[r_index] + " should be >= 0");
}
if (P[1] > 0) {
/* r[n] = sub(0, r[n]) */
r[r_index] = (short) (-(r[r_index]));
}
if (r[r_index] == Gsm_Def.MIN_WORD) {
throw new IllegalArgumentException(
"Reflection_coefficients: r["
+ r_index
+ "] = "
+ r[r_index]
+ " should not be "
+ Gsm_Def.MIN_WORD);
}
if (n == 8) {
return;
}
/* Schur recursion
*/
temp = Add.GSM_MULT_R(P[1], r[r_index]);
P[0] = Add.GSM_ADD(P[0], temp);
for (int m = 1; m <= 8 - n; m++) {
temp = Add.GSM_MULT_R(K[m], r[r_index]);
P[m] = Add.GSM_ADD(P[m + 1], temp);
temp = Add.GSM_MULT_R(P[m + 1], r[r_index]);
K[m] = Add.GSM_ADD(K[m], temp);
}
}
}
