Simple Assembly Loop

[diltsman]

When I attempt to compile the following code I get an error "./src/app_test.S:5: Error: A00004 Unknown opcode 'brbu'".

Code: Select all

  .text
  .align 2
  .globl _start
_start:
  brbu _start

I am not compiling against any of the C runtime, so _start should be the entry point. How is it that this will not compile? BRBU is an opcode on page 62 of The XMOS XS1 Architecture?

[Guest]

While BRBU is the CPU-level opcode, the assembler does some of the final opcode selection for you, such as choosing forward/backward jump, or long/short literal variants of the instruction. The asm instruction you're looking for is bu _start.

The assembly programming manual lists the instructions accepted by the assembler.

[JohnWilson]

Also, the raw (vs. massaged for direction etc.) mnemonics are in upper case. So it would have been BRBU not brbu. Yes the assembler is case-sensitive ...