Program Control
3
3 – 26
There is no standard PUSH PC stack instruction. To push a specific value
onto the PC stack, therefore, use the following special instruction:
TOPPCSTACK
=
reg;
{push reg contents onto PC stack}
The stack is pushed immediately, in the same cycle.
Examples:
AX0
=
TOPPCSTACK;
{pop PC stack into AX0}
NOP;
TOPPCSTACK
=
I7;
{push contents of I7 onto PC stack}
Only the following registers may be used in the special TOPPCSTACK
instructions:
ALU, MAC,
& Shifter
DAG
Registers
Registers
AX0
I0
I4
AX1
I1
I5
MX0
I2
I6
MX1
I3
I7
AY0
M0
M4
AY1
M1
M5
MY0
M2
M6
MY1
M3
M7
AR
L0
L4
MR0
L1
L5
MR1
L2
L6
MR
L3
L7
SI
SE
SR0
SR1
The Type 17 Register Move instruction is described in Chapter 15,
Instruction Set Reference. Note that TOPPCSTACK may not be used as a
register in any other instruction type!