From Micro to Macro

1
From Micro- to Macro-

• Each machine instruction is itself a program
• Control store has microinstructions
• 1 instruction sequence of microinstructions
• But, a few things to cover first
• Memory organization and stacks
• Instruction set organization

2
Memory Organization

• What happens when an application loads?
• List of instructions established in RAM
• Ditto for data (constants and initial variables)
• Instructions arranged in groups
• Each procedure/method accounts for a group
• Data arranged in groups
• Blocked/framed according to procedure calls

3
A Simple Stack Example
4
Stack During Invocation
5
Stack During Return
6
Some IJVM Instructions

• Most deal with data on the stack
• POP (0x57) - delete word
• IADD (0x60) - add two words
• IINC (0x84) - add a constant to a word
• IAND (0x7E) - and two words
• IF_ICMPEQ (0x9F) - branch if equal
• SWAP (0x5F) - exchange values

7
Translating High-Level to Assembler
ILOAD j ILOAD k IADD ISTORE i ILOAD
i BIPUSH 3 IF_ICMPEQ L1 ILOAD j BIPUSH
1 ISUB ISTORE j GO TO L2 L1 BIPUSH 0 ISTORE
k L2
i j k if (i 3) k 0 else j j - 1
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The IADD Instruction
iadd1 MAR SP SP - 1 rd iadd2 H
TOS iadd3 MDR TOS MDR H wr goto Main1