Package asm

The Cebollita assembler implements a subset of standard MIPS assembly language.

See:
Description

Class Summary

Asm	Entry point to the assembler.
AsmData	An abstract class representing literal data in an assembly file.
AsmDataSpace	Assembly file space directive.
AsmDataString	Assembly file string as data.
AsmDataWord	Assembly file word as data.
AsmFile	Represents a file of assembly code.
AsmIns	Represents a single assembly instruction.
Linker	The Linker takes multiple object files and produces a single executable.
Module	Used to represent a single object file.

Package asm Description

The Cebollita assembler implements a subset of standard MIPS assembly language. The assembler is somewhat table driven, so the actual set of MIPS instructions that it handles can vary. However, here is the bare minimum set of instructions it can and does encode:

Arithmetic

ADD, ADDI, SUB, MULT*, DIV*, SLT, SLTI

Logic

OR, ORI, AND, ANDI, XOR, XORI, SLL, SRL, SRA, SLLV, SRAV, SRLV

Memory

LW, SW, LB, SB

Control

J, JAL, JR, BEQ, BNE, BLEZ, BGTZ

Random

SYSCALL, BREAK, NOP, RFE, MFC0, MTC0

(*) In the Cebollita world, MULT and DIV are implemented as regular R-type (three register) instructions. They do not make use of the HI and LO registers -- rather, they simply place the 32 interesting (low) bits of their result into the destination register. The high bits are discarded.

Running the assembler:

Please see the tools section for the definitive guide to using this tool.

This will create a file called file.o:

  java asm.parser file.s

Passing the --version flag will print out version info.

MIPS assembly subset

The Cebollita MIPS assembler implements a subset of real MIPS assembly. Instructions: It implements most of the standard R-type, I-type, and J-type instructions for arithmetic, control, and memory operations. It does not handle floating point instructions, or ANY pseudo-operations. Pseudo-ops are a lie that confuse the capabilities of the assembler, and have no real place in an introductory setting like this.

Data: The following data directives are the only ones recognized:

[label] .space [bytes]
[label] .word  [value]
[label] .asciiz [string]

Because of limitations of the linker, labels can ONLY be used in conjunction with BEQ, BNE, BGTZ, BLTZ, LW, SW, LB, SB, J, JAL, ADDI, ORI.

Running the linker:

Please see the tools section for the definitive guide to using this tool.

This will link the two provided files:

  java asm.Linker file1.o file2.o

The linker understand the following flag:

--bare

spit out a bare executable (just instructions).

--version

spit out version info and die

--at [address]

link the executable as if it living at [address] (default 0)

--start [label]

use [label] for the executable entry point (default __start)

Inspecting a module:

Please see the tools section for the definitive guide to using this tool.

This will spit out information about an object file:

  java asm.Module file1.o