Propeller Manual

WRWORD – Assembly Language Reference
WRWORD
Instruction: Write a word to main memory.
WRWORD Value, 〈#〉 Address
• Value (d-field) is the register containing the 16-bit value to write to main memory.
•
Address (s-field) is a register or a 9-bit literal whose value is the main memory
address to write to.
Opcode Table:
–INSTR– ZCRI –CON– –DEST– –SRC– Z Result C Result Result Clocks
000001 000i 1111 ddddddddd sssssssss
--- --- Not Written 7..22
Concise Truth Table:
In Out
Destination Source Z C Effects Destination
1
Z
2
C
$----_----; - $----_----; - - -
wz wc
n/a 1 0
1
Destination Out doesn’t exist since including a WR effect would turn WRWORD into a RDWORD instruction.
2
The Z flag is set (1) unless the main memory address (bits 13:1) is on a long boundary.
Explanation
WRWORD synchronizes to the Hub and writes the lowest word in Value to main memory at
Address.
The
WR effect can not be used with WRWORD as that would change it to a RDWORD instruction.
WRWORD is a hub instruction. Hub instructions require 7 to 22 clock cycles to execute
depending on the relation between the cog’s hub access window and the instruction’s moment
of execution. See Hub on page 24 for more information.
Page 376 · Propeller Manual v1.1