dspl.backend
Class AssemblyfileGenerator

java.lang.Object
  dspl.backend.AssemblyfileGenerator

public class AssemblyfileGenerator
extends java.lang.Object

Utility used to actually write the provided assembly file and instructions

Author:

dlariviere

Field Summary

private int	nextBranchLabelNum Used to generate unique labels for branching/control flow.
private int	nextStringID Used to generate labels for string constants
private java.util.HashMap	stringLabelsHashMap
private java.io.PrintWriter	writer PrintWriter responsible for writing instructions directly to the asm file
private boolean	writeStdOut If true, all data written to asm file will also be written to std out

Constructor Summary

AssemblyfileGenerator(java.lang.String outputFilename, boolean writeStdOut)
Create an AssemblyfileGenerator to write a basic assembly program to the target file

Method Summary

void	closeFile() Called after the program is done writing instructions to the generator.
java.lang.String	getBranchLabel() Returns a unique branch label to be used for branch instructions
java.lang.String	getStringLabel(Variable stringVar) Returns the label used to refer to a particular String that should've been added to the data section of the ASM file
private void	outputILine(java.lang.String line) Output tabbed (indented) line
private void	outputLine(java.lang.String line) Output line
void	writeAsmInstr(java.lang.String op, java.lang.String arg) Writes one operand ASM instruction
void	writeAsmInstr(java.lang.String op, java.lang.String src, java.lang.String dest) Writes a standard two operand ASM instruction
private void	writeBSSSection(java.util.ArrayList variables) Writes the BSS section, which includes all variables that are not explicitly defined before hand.
private void	writeDataSection(java.util.ArrayList variables) Generate the data section for the program based on its variables.
void	writeLabel(java.lang.String label) Writes an ASM label Example: "L10:"
void	writeSkeletonASM(java.util.ArrayList variables) Generates the initial Assembly file given it's variables Should be called before all other write commands are called on it
void	writeStdEntrySeq() Writes standard entry sequence for a function according to Intel ABI Note: does not handle allocating additional space on the stack for local variables
void	writeStdOutputSeq() Writes standard exit sequence for a function

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

nextBranchLabelNum

private int nextBranchLabelNum

Used to generate unique labels for branching/control flow.

nextStringID

private int nextStringID

Used to generate labels for string constants

writer

private java.io.PrintWriter writer

PrintWriter responsible for writing instructions directly to the asm file

writeStdOut

private boolean writeStdOut

If true, all data written to asm file will also be written to std out

stringLabelsHashMap

private java.util.HashMap stringLabelsHashMap

Constructor Detail

AssemblyfileGenerator

public AssemblyfileGenerator(java.lang.String outputFilename,
                             boolean writeStdOut)
                      throws java.io.FileNotFoundException

Create an AssemblyfileGenerator to write a basic assembly program to the target file

Parameters:

outputFilename: - name of ASM file to write to

writeStdOut - if true, all data written to the file will also be printed to standard out

Throws:

FileNotFoundException: - thrown when file cannot be opened

java.io.FileNotFoundException

Method Detail

closeFile

public void closeFile()

Called after the program is done writing instructions to the generator.
Responsible for flushing and closing the file.

getBranchLabel

public java.lang.String getBranchLabel()

Returns a unique branch label to be used for branch instructions

Returns:

outputLine

private void outputLine(java.lang.String line)

Output line

Parameters:

line: - line to write to file

outputILine

private void outputILine(java.lang.String line)

Output tabbed (indented) line

Parameters:

line: - line to write to file, prepended by tab

getStringLabel

public java.lang.String getStringLabel(Variable stringVar)

Returns the label used to refer to a particular String that should've been added to the data section of the ASM file

Parameters:

stringVar -

Returns:

writeSkeletonASM

public void writeSkeletonASM(java.util.ArrayList variables)

Generates the initial Assembly file given it's variables
Should be called before all other write commands are called on it

Parameters:

variables -

writeDataSection

private void writeDataSection(java.util.ArrayList variables)

Generate the data section for the program based on its variables.

All atomic elements and initially declared variables go in the symbol table.

The only elements that do not are arrays whose defintion is unknown ("i.e.: int_array iA[5];"), which should instead be put in the .bss section

Parameters:

variables -

writeBSSSection

private void writeBSSSection(java.util.ArrayList variables)

Writes the BSS section, which includes all variables that are not explicitly defined before hand.

BSS declared variables differ from those in the Data segment in that variables created in the BSS section to not allocate space within the actual executable, unlike in the Data section where allocating a 1000 element array would actually make the final executable 1000 * sizeof(array element) bigger

Parameters:

variables -

writeStdEntrySeq

public void writeStdEntrySeq()

Writes standard entry sequence for a function according to Intel ABI
Note: does not handle allocating additional space on the stack for local variables

writeStdOutputSeq

public void writeStdOutputSeq()

Writes standard exit sequence for a function

writeAsmInstr

public void writeAsmInstr(java.lang.String op,
                          java.lang.String src,
                          java.lang.String dest)

Writes a standard two operand ASM instruction

writeAsmInstr

public void writeAsmInstr(java.lang.String op,
                          java.lang.String arg)

Writes one operand ASM instruction

Parameters:

op -

arg -

writeLabel

public void writeLabel(java.lang.String label)

Writes an ASM label
Example: "L10:"

Parameters:

label -