National Instruments HPC167064 - Manual (Page 28)

HPC167064 CPU
The HPC167064 CPU has a 16-bit ALU and six 16-bit regis-
ters
Arithmetic Logic Unit (ALU)
The ALU is 16 bits wide and can do 16-bit add subtract and
shift or logic AND OR and exclusive OR in one timing cycle
The ALU can also output the carry bit to a 1-bit C register
Accumulator (A) Register
The 16-bit A register is the source and destination register
for most I O arithmetic logic and data memory access op-
erations
Address (B and X) Registers
The 16-bit B and X registers can be used for indirect ad-
dressing They can automatically count up or down to se-
quence through data memory
Boundary (K) Register
The 16-bit K register is used to set limits in repetitive loops
of code as register B sequences through data memory
Stack Pointer (SP) Register
The 16-bit SP register is the pointer that addresses the
stack The SP register is incremented by two for each push
or call and decremented by two for each pop or return The
stack can be placed anywhere in user memory and be as
deep as the available memory permits
Program (PC) Register
The 16-bit PC register addresses program memory
Addressing Modes
ADDRESSING MODES ACCUMULATOR AS
DESTINATION
Register Indirect
This
is the ‘‘normal’’ mode of addressing for the
HPC167064 (instructions are single-byte) The operand is
the memory addressed by the B register (or X register for
some instructions)
Direct
The instruction contains an 8-bit or 16-bit address field that
directly points to the memory for the operand
Indirect
The instruction contains an 8-bit address field The contents
of the WORD addressed points to the memory for the oper-
and
Indexed
The instruction contains an 8-bit address field and an 8- or
16-bit displacement field The contents of the WORD ad-
dressed is added to the displacement to get the address of
the operand
Immediate
The instruction contains an 8-bit or 16-bit immediate field
that is used as the operand
Register Indirect (Auto Increment and Decrement)
The operand is the memory addressed by the X register
This mode automatically increments or decrements the X
register (by 1 for bytes and by 2 for words)
Register Indirect (Auto Increment and Decrement) with
Conditional Skip
The operand is the memory addressed by the B register
This mode automatically increments or decrements the B
register (by 1 for bytes and by 2 for words) The B register is
then compared with the K register A skip condition is gener-
ated if B goes past K
ADDRESSING MODES DIRECT MEMORY AS
DESTINATION
Direct Memory to Direct Memory
The instruction contains two 8- or 16-bit address fields One
field directly points to the source operand and the other field
directly points to the destination operand
Immediate to Direct Memory
The instruction contains an 8- or 16-bit address field and an
8- or 16-bit immediate field The immediate field is the oper-
and and the direct field is the destination
Double Register Indirect Using the B and X Registers
Used only with Reset Set and IF bit instructions a specific
bit within the 64 kbyte address range is addressed using the
B and X registers The address of a byte of memory is
formed by adding the contents of the B register to the most
significant 13 bits of the X register The specific bit to be
modified or tested within the byte of memory is selected
using the least significant 3 bits of register X
HPC Instruction Set Description
Mnemonic Description Action
ARITHMETIC INSTRUCTIONS
ADD Add MAaMemI x MA carry x C
ADC Add with carry MAaMemIaCMA carry x C
ADDS Add short imm8 Aaimm8 x A carry x C
DADC Decimal add with carry MAaMemIaC x MA (Decimal) carry x C
SUBC Subtract with carry MAbMemIaC x MA carry x C
DSUBC Decimal subtract w carry MAbMemIaC x MA (Decimal) carry x C
MULT Multiply (unsigned) MA MemI x MA X 0 x K 0 x C
DIV Divide (unsigned) MA MemI x MA rem x X 0 x K 0 x C
DIVD Divide Double Word (unsigned) X MA MemI x MA rem x X 0 x K carry x C
IFEQ If equal Compare MA MemI Do next if equal
IFGT If greater than Compare MA MemI Do next if MA l MemI
AND Logical AND MA and MemI x MA
OR Logical OR MA or MemI x MA
XOR Logical Exclusive-OR MA xor MemI x MA
MEMORY MODIFY INSTRUCTIONS
INC Increment Mem a 1 x Mem
DECSZ Decrement skip if 0 Mem b1 x Mem Skip next if Mem e 0
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