Propeller Manual

Table Of Contents

3: Assembly Language Reference – CALL

Propeller Manual v1.1 · Page 269

instruction is really just a JMP instruction without a hard-coded destination address, and this

run-time action provides it with the “return” address to jump back to. After storing the return

address,

CALL jumps to the destination address; Symbol.

The diagram below uses a short program example to demonstrate the

CALL instruction’s run-

time behavior; the store operation (left) and the jump-execute-return operation (right).

Figure 3-1: Run-time CALL Procedure

Store operation Jump, execute and return operation

this example, the following occurs when the

CALL instruction is reached at run time:

source

②

y leading to the

Routine_ret line.

rce

① The cog stores the return address (PC+1; that of

<next instruction>) into the

(s-field) of the register at

Routine_ret (see left image).

The cog jumps to Routine (see right image).

③

Routine’s instructions are executed, eventuall

④ Since the

Routine_ret location contains a RET instruction with an updated sou

(s-field), which is the return address written by step 1, it returns, or jumps, back to

the

<next instruction> line.