Propeller Manual

3: Assembly Language Reference – WAITPEQ
Propeller Manual v1.1 · Page 369
WAITPEQ
Instruction: Pause a cog’s execution until I/O pin(s) match designated state(s).
WAITPEQ State, 〈#〉 Mask
• State (d-field) is the register with the target state(s) to compare against INx ANDed
with Mask.
•
Mask (s-field) is the register or a 9-bit literal whose value is bitwise ANDed with INx
before the comparison with State.
Opcode Table:
–INSTR– ZCRI –CON– –DEST– –SRC– Z Result C Result Result Clocks
111100 000i 1111 ddddddddd sssssssss
--- --- Not Written 5+
Concise Truth Table:
In Out
Destination Source Z C Effects Destination
1
Z C
$0000_0000; 0 $0000_0000; 0 - -
wr wz wc
$0000_0000; 0 1 0
$0000_0000; 0 $0000_0001; 1 - -
wr wz wc
$0000_0001; 1 0 0
$0000_0001; 1 $0000_0001; 1 - -
wr wz wc
$0000_0002; 2 0 0
$0000_0000; 0 $0000_0002; 2 - -
wr wz wc
$0000_0002; 2 0 0
$0000_0002; 2 $0000_0002; 2 - -
wr wz wc
$0000_0004; 4 0 0
1
Destination is not written unless the WR effect is given.
Explanation
WAITPEQ, “Wait for Pin(s) to Equal,” is one of four wait instructions (WAITCNT, T WAITPEQ,
WAITPNE, and WAITVID) used to pause execution of a cog until a condition is met. The WAITPEQ
instruction pauses the cog until the result of
INx ANDed with Mask equals the value in the
State register.
INx is either INA or INB depending on the value of the C flag upon execution;
INA if C = 0, INB if C = 1 (the P8X32A is an exception to this rule; it always tests INA).
The
WAITPEQ instruction behaves similar to Spin’s WAITPEQ command; see WAITPEQ on page
222.