NonStop S-Series Server Description Manual (G06.24+)

TNS Instruction Set

HP NonStop S-Series Server Description Manual—520331-003

11-8

Move, Compare, and Scan Instructions

One bit in the instruction word format of nonextended memory-to-memory move,

compare, and scan instructions specifies an ascending order or descending order of

addresses used for the source and destination of the moved data. Starting addresses

for the destination and the source are specified in the register stack, as well as the

count of elements to be moved.

Figure 11-7 provides a comparison of ascending and descending moves, compares,

and scans, as described in the instruction definitions for MOVW, MOVB, COMW,

COMB, SBW, and SBU.

Note that bit 9 of the instruction word format specifies ascending order of addresses if

0 and descending order if 1. Elements are 16-bit words for MOVW and COMW (Move

Words and Compare Words). Elements are bytes for MOVB, COMB, SBW, and SBU

(Move Bytes, Compare Bytes, Scan Bytes While, and Scan Bytes Until).

The upper example shows an ascending move (or compare or scan). Register A

specifies the count of elements involved, B specifies the source address, and C

specifies the destination address. These values are updated as the operation

progresses.