HPC-DEV-WDBC datasheet(25/30 Pages) NSC

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HPC Instruction Set Description (Continued)

Mnemonic

Description

Action

TRANSFER OF CONTROL INSTRUCTIONS

JSRP

Jump subroutine from table

xW(SP)SPa2xSP

W(table )

xPC

JSR

Jump subroutine relative

xW(SP)SPa2xSPPCa xPC

( is a1024 to b1023)

JSRL

Jump subroutine long

xW(SP)SPa2xSPPCa xPC

Jump relative short

PCa

xPC( is a32 to b31)

JMP

Jump relative

PCa

xPC( is a256 to b255)

JMPL

Jump relative long

PCa

xPC

JID

Jump indirect at PC a APCaAa1

xPC

JIDW

then Mem(PC)aPC

xPC

NOP

No Operation

wPC a 1

RET

Return

SPb2

xSPW(SP)xPC

RETS

Return then skip next

SPb2

xSPW(SP)xPC

skip

RETI

Return from interrupt

SPb2

xSPW(SP)xPC interrupt re-enabled

Note

W is 16-bit word of memory

MA is Accumulator A or direct memory (8-bit or 16-bit)

Mem is 8-bit byte or 16-bit word of memory

MemI is 8-bit or 16-bit memory or 8-bit or 16-bit immediate data

imm is 8-bit or 16-bit immediate data

Memory Usage

For information on memory usage and instruction timing

please refer to the HPC46400E User’s Manual (See page

25 for ordering information)

Code Efficiency

The HPC46400E has been designed to be extremely code-

efficient The HPC46400E looks very good in all the stan-

dard coding benchmarks however it is not realistic to rely

only on benchmarks Many large jobs have been pro-

grammed onto the HPC46400E and the code savings over

other popular microcontrollers has been considerable

Reasons for this saving of code include the following

SINGLE BYTE INSTRUCTIONS

The majority of instructions on the HPC46400E are single-

byte There are two especially code-saving instructions

JP is a 1-byte jump True it can only jump within a range of

plus or minus 32 but many loops and decisions are often

within a small range of program memory Most other micros

need 2-byte instructions for any short jumps

JSRP is a 1-byte call subroutine The user makes a table of

his 16 most frequently called subroutines and these calls

will only take one byte Most other micros require two and

even three bytes to call a subroutine The user does not

have to decide which subroutine addresses to put into his

table the assembler can give him this information

EFFICIENT SUBROUTINE CALLS

The 2-byte JSR instructions can call any subroutine within

plus or minus 1k of program memory

MULTIFUNCTION INSTRUCTIONS FOR DATA MOVE-

MENT AND PROGRAM LOOPING

The HPC46400E has single-byte instructions that perform

multiple tasks For example the XS instruction will do the

following

1 Exchange A and memory pointed to by the B register

2 Increment or decrement the B register

3 Compare the B register to the K register

4 Generate a conditional skip if B has passed K

The value of this multipurpose instruction becomes evident

when looping through sequential areas of memory and exit-

ing when the loop is finished

BIT MANIPULATION INSTRUCTIONS

Any bit of memory IO or registers can be set reset or

tested by the single byte bit instructions The bits can be

addressed directly or indirectly Since all registers and IO

are mapped into the memory it is very easy to manipulate

specific bits to do efficient control

DECIMAL ADD AND SUBTRACT

This instruction is needed to interface with the decimal user

world

It can handle both 16-bit words and 8-bit bytes

The 16-bit capability saves code since many variables can

be stored as one piece of data and the programmer does

not have to break his data into two bytes Many applications

store most data in 4-digit variables The HPC46400E sup-

plies 8-bit byte capability for 2-digit variables and literal vari-

ables

MULTIPLY AND DIVIDE INSTRUCTIONS

The HPC46400E has 16-bit multiply 16-bit by 16-bit divide

and 32-bit by 16-bit divide instructions This saves both

code and time Multiply and divide can use immediate data

or data from memory The ability to multiply and divide by

immediate data saves code since this function is often

needed for scaling base conversion computing indexes of

arrays etc

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