readme.minimips

基于4个mips核的noc设计

Where to start?

	set envionment variable LCCDIR to the directory that contains
	lcc and add $LCCDIR to PATH. Use lcc to compile your program.
	For example: "lcc -o stanford stanford.c".

What are the size of the standard data types?

	* sizeof(char) = 1
	* sizeof(short) = 4
	* sizeof(int) = 4
	* sizeof(long) = 4
	* sizeof(float) = 4
	* sizeof(double) = 4

Which software is used?

	* Lcc v4.1		// compiler
	* Binutils v2.11.2	// assmbler, linker
	* SoftFloat v2b		// floating point emulation
	* BSD4.3 libc		// libc
	* Oink v1.0		// MIPS simulator

Which endianess is used?

	Big-endian

How to specify the load address?

	$LCCDIR/minimips.link. See gld documentation for more information.
	Default load address is 0x1fc00000.

What is the output format of the linker?

	Elf format. Commandline options --oformat=srec or --oformat=binary
	can be used to create binaries in srecord or binary format
	respectively.

How to use custom ops?

	#define sfu0(a, b)       ((a) + ((b) + *(int *) 0x12344321))
	#define sfu1(a, b)       ((a) - ((b) + *(int *) 0x12344321))
	#define sfu2(a, b)       ((a) + ((b) - *(int *) 0x12344321))
	#define sfu3(a, b)       ((a) - ((b) - *(int *) 0x12344321))

	The four custom ops are mapped on instructions:

	msb			     lsb

	000000ssssstttttddddd00000110000 /* Special 0x30 == sfu0 */
	000000ssssstttttddddd00000110001 /* Special 0x31 == sfu1 */
	000000ssssstttttddddd00000110010 /* Special 0x32 == sfu2 */
	000000ssssstttttddddd00000110011 /* Special 0x33 == sfu3 */

	sssss = rs, ttttt = rt, and ddddd = rd.

	Modify minimips.md if you want to add more custom ops or
	in the case you want to change the encoding.

	Because .words are emited for custom ops, you don't have to
	change the assembler.

Which MIPS operations are used by lcc for MINIMIPS?

	* addiu addu subu
	* and andi or ori xor xori
	* beq bne
	* jal jalr jr j
	* lb lw sb sw
	* lui
	* slti sltiu slt sltu
	* sll sra srl (1, 2, 8 bits)

Which linker/assembler/archiver?

	GNU binutils is used. Configure it with --target=mips. Put mips-* 
	tools in $LCCDIR.

Which operations are emulated in software?

	* All floating point operations
	* Multiply, divide, modulo
	* Variable distance shifts 
	* Partial-word operations

How to disassemle (Elf) code?

	mips-objdump -d <file name>

How to change the stack size and heap size?

	Modify constants stack_size and heap_size in lib/crt0.s.
	Default values are 10k and 100k, respectively.

How to generate code for MIPS (in order to compare it with MINIMIPS)?

	Use lcc's -target=mips/irix option.

How to simulate MIPS/MINIMIPS code?

	Use oink -f <file name>. Use Oink's -p 0x10c2000c option to make 
	printf work.