W90210F Datasheet, PDF (66/67 Pages) Winbond – PA-RISC EMBEDDED CONTROLLER

W90210F
Load Halfword Unpacked
LDHU
Format:
LDHU, cmplt d(s,b),t
0:5
5:10
11:15
21:25 26 27:31
05
b im5 s a - 14 m t
6
5 5 213 5 1 5
Purpose:
To load a halfword and unpack into a general register.
Description: The aligned halfword at the effective address is uppacked into two bytes, zero-extended to
two halfwords and loaded into GR t. The completer, cmplt, determines if the offset is the
base register, b, or the base register plus the short displacement, d. The displacement is
encoded in the im5 field. The completer, encoded in the a and m fields of the instruction,
also specifies base register modification. If base register modification is specified and b=t,
the value loaded is the unpacked halfwords at the effective address.
Operation: switch (cmplt) {
case MB: offset ← GR[b] + low_sign_ext(im5,5); /* a=1,m=1 */
GR[b] ← GR[b] + low_sign_ext(im5,5);
break;
case MA: offset ← GR[b];
/* a=0,m=1 */
GR[b] ← GR[b] + low_sign_ext(im5,5);
break;
default: offset ← GR[b] + low_sign_ext(im5,5); /* m=0 */
break;
}
GR[t] ← cat(zero_ext(mem_load(offset,0,7),16), zero_ext(mem_load(offset,8,15),16))
Exception: None.
Restriction: Winbond defined instruction for W90210F.
66
The above information is the exclusive intellectual property of Winbond Electronics Corp. and shall not be disclosed, distributed or reproduced without permission from Winbond.
Version 1.4, 10/8/97