What does ## mean in Prop-2 assembly language?

JonTitus

I have seen the double pound sign symbol (##) used in several assembly-language programs for the Propeller-2, but don't understand what it means. It's not mentioned in the Prop-1 docs. Can someone offer an explanation and an example?

Thanks. --Jon

Wuerfel_21

It inserts an AUGS and/or AUGD instruction before the actual instruction to allow for large immediates

whicker

It means you want a value larger than 511, at the cost of doubling the size of the instruction.

JonTitus

Ah, perfect. Thank you both. --Jon

Cluso99

## if used in the D operand (main use) then the instruction

[label]  opcode  [#]S,##D

will become 2 instructions something like

label  AUGD    #(D>>9)            ' D[22:0] are 23-bits forwarded to D [31:9] in the next instruction
       opcode  [#]S,#(D & $1FF)   ' D[8:0] plus the forwarded D[31:9] from the previous instruction

such that the AUGS instruction feeds the top 23 bits [31:9] (ie 32-9) bits which gets fed forward to be used in the next "S" instruction when it executes. Note that addresssing is only 20 bits, so if it's an address in the next instruction, only the bits [19:0} will be forwarded. This allows for the following instruction to be able to load a register with a full 32 bit value. The following instruction provides the bits [8:0] (ie 9 lower bits) which are combined with those forwarded by the previous AUGS instruction.

AUGD provides a similar method for the D bits in the following instruction.

evanh

There is very terse pasm2 description in "Instructions.txt" of the Pnut zip download. Should be some help - https://forums.parallax.com/discussion/171196/pnut-spin2-latest-version-v34r

Rayman

You picked a great time to learn PASM!
In the past, it was a pain to use any numeric value > 511
Now, it's no problem! Just use ## and the assembler will magically make it all work.
(It just adds an extra instruction)