3
Program Control
3 – 25
Syntax
Status Condition
True If:
EQ
Equal Zero
AZ = 1
NE
Not Equal Zero
AZ = 0
LT
Less Than Zero
AN .XOR. AV = 1
GE
Greater Than or Equal Zero AN .XOR. AV = 0
LE
Less Than or Equal Zero
(AN .XOR. AV) .OR. AZ = 1
GT
Greater Than Zero
(AN .XOR. AV) .OR. AZ = 0
AC
ALU Carry
AC = 1
NOT AC
Not ALU Carry
AC = 0
AV
ALU Overflow
AV = 1
NOT AV
Not ALU Overflow
AV = 0
MV
MAC Overflow
MV = 1
NOT MV
Not MAC Overflow
MV = 0
NEG
X Input Sign Negative
AS = 1
POS
X Input Sign Positive
AS = 0
NOT CE
Not Counter Expired
—
FLAG_IN*
FI pin
Last sample of FI pin = 1
NOT FLAG_IN* Not FI pin
Last sample of FI pin = 0
* Only available on JUMP and CALL instructions.
Table 3.9 IF Condition Logic
3.7
TOPPCSTACK
A special version of the Register-to-Register Move instruction, Type 17, is
provided for reading (and popping) or writing (and pushing) the top
value of the PC stack. The normal POP PC instruction does not save the
value popped from the stack, so to save this value into a register you must
use the following special instruction:
reg
=
TOPPCSTACK;
{pop PC stack into reg}
{“toppcstack” may also be
lowercase}
The PC stack is also popped by this instruction, after a one-cycle delay.
A NOP should usually be placed after the special instruction, to allow the
pop to occur properly:
reg
=
TOPPCSTACK;
NOP;
{allow pop to occur correctly}