Intel ITANIUM ARCHITECTURE - SOFTWARE DEVELOPERS MANUAL VOLUME 3 REV 2.3 Manual page 237

psub
Operation: if (PR[qp]) {
check_target_register(r
if (one_byte_form) {
x[0] = GR[r
x[1] = GR[r
x[2] = GR[r
x[3] = GR[r
x[4] = GR[r
x[5] = GR[r
x[6] = GR[r
x[7] = GR[r
if (sss_saturation_form) {
} else if (uus_saturation_form) {
} else if (uuu_saturation_form) {
} else {
}
if (sss_saturation_form || uus_saturation_form ||
}
GR[r
} else if (two_byte_form) {
x[0] = GR[r
x[1] = GR[r
x[2] = GR[r
x[3] = GR[r
if (sss_saturation_form) {
3:228
);
1
]{7:0};
2
]{15:8};
2
]{23:16};
2
]{31:24};
2
]{39:32};
2
]{47:40};
2
]{55:48};
2
]{63:56};
2
max = sign_ext(0x7f, 8);
min = sign_ext(0x80, 8);
for (i = 0; i < 8; i++) {
temp[i] = sign_ext(x[i], 8) - sign_ext(y[i], 8);
}
max = 0xff;
min = 0x00;
for (i = 0; i < 8; i++) {
temp[i] = zero_ext(x[i], 8) - sign_ext(y[i], 8);
}
max = 0xff;
min = 0x00;
for (i = 0; i < 8; i++) {
temp[i] = zero_ext(x[i], 8) - zero_ext(y[i], 8);
}
for (i = 0; i < 8; i++) {
temp[i] = zero_ext(x[i], 8) - zero_ext(y[i], 8);
}
uuu_saturation_form) {
for (i = 0; i < 8; i++) {
if (temp[i] > max)
temp[i] = max;
if (temp[i] < min)
temp[i] = min;
}
] = concatenate8(temp[7], temp[6], temp[5], temp[4],
1
temp[3], temp[2], temp[1], temp[0]);
]{15:0};
2
]{31:16};
2
]{47:32};
2
]{63:48};
2
y[0] = GR[r ]{7:0};
3
y[1] = GR[r ]{15:8};
3
y[2] = GR[r ]{23:16};
3
y[3] = GR[r ]{31:24};
3
y[4] = GR[r ]{39:32};
3
y[5] = GR[r ]{47:40};
3
y[6] = GR[r ]{55:48};
3
y[7] = GR[r ]{63:56};
3
y[0] = GR[r ]{15:0};
3
y[1] = GR[r ]{31:16};
3
y[2] = GR[r ]{47:32};
3
y[3] = GR[r ]{63:48};
3
// one-byte elements
// sss_saturation_form
// uus_saturation_form
// uuu_saturation_form
// modulo_form
// two-byte elements
// sss_saturation_form
Volume 3: Instruction Reference