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herkforth's PPC assembler

"There are only 10 types of people in the world: Those who understand binary, and those who don't"

<hSyntax<>

This assembler does not use the standard syntax. To assemble an instruction you
put all the parameters on the stack (see Syntax Exceptions below) and call the
word to assemble it (which is an underscore followed by the mnemonic.)

Example:

To assemble rlwinm equivalent to the following:

You would do:

Define a word according to the naming scheme (underscore followed by mnemonic.)

Call <copcode<> (or <c2opcode<> if your instruction has a secondary opcode.)
This gets the assembling started by clearing all bits in the A register, and
then putting the opcode(s) in. If your instruction has a standard form (such as
2 five bit fields followed by a 16 bit field) you can just call the appropriate
word for that form and you're done (<c_5-5-16<> in this case.) If there is not
a word for assembling the form for your instruction, either make it, or use the
words such as <c|51 |52 |10<> etc. to or in the operands.

Here's how I wrote <c_rlwinm<>:

<c: _5-5-5-5-5 opcode |55 |54 |53 |51 |52 a, ;<>

<c: _rlwimi 21 _5-5-5-5-5 ;<>

<copcode<> ( x -- )  call this (first) to shift the opcode up and put it in the
A register

<c|51<> ( x -- ) or x into the a register as the 1st 5 bit operand

<c|52<> ( x -- ) or x into the a register as the 2nd 5 bit operand

<c|10<> ( x -- ) or x into the a register as the 10 bit field

See blocks/005 for complete reference

This section describes the exceptions to the rule that you put the parameters
for your instruction on the stack in the same order that they are documented in
standard PPC assembly documentation.

1) load/store with immediate: these take the immediate on top of the stack. eg:
_stw _lwz

2) in cmp I've combined the first two operands and the reserved bit. so pass
the condition register field shifted up two.

<lrlwinm<> (PPC instruction "Rotate Left Word Immediate then aNd with Mask")

<lherkforth<>

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