Syntax¶
orangejuice’s syntax is based on AT&T syntax. Source operands preceed destination operands. However, because Magpie is RISC, there’s no need for loads of glyphs and punctuation.
Instructions¶
All I format instructions are written the same:
name value rd
value is either an integer literal or identifier. There is also an additional fake instruction: ldi, load immediate. ldi desugars into a ldl and a ldh upon being parsed, making it simpler to write a 16-bit load.
M format instructions are written:
name ra ro rd
J format instructions are written:
name destination
destination can be a literal or an identifier. orangejuice will automatically work out the excess-K offset for you.
Almost all R format instructions are written the same:
name rs rd
The exceptions are int (just written as int); gf, gr, not (written name rd); and sf (written sf rs).
Registers¶
Registers 0-15 are available as r0 through to r15. There are also some aliases:
pc for r15
link for r14
sp for r13
0 for r0
Identifiers and labels¶
Labels are defined in the usual way: the name and then a colon at the start of a line. Arbitrary values can be defined with the .set directive.
Values can be referred to with either just the name, or the name followed by /l for the lower 8 bits, or the name followed by /h for the upper 8 bits.