CS 2734 Computer Organization II

Lecture 11: Program Layout and Variables - 2/10/97

Answers to Informal Quiz 2: Tracing Instruction Cycle
Program layout (refer to Figure 9.1 on page 229 of Paul).
- Text segment - program code (starts at 0x2000 in Sparc).
- Data segment - initialized static variables.
- bss - uninitialized static variables are initialized to zero.
- Heap - where malloc obtains free space.
- Stack
- Environment
Defining a one-dimensional array in the data segment using:
- .word
- .byte
- .ascii
- .asciz
Defining data in the bss:
- .common name,bytes
- The .align is used to align data.
Addressing of memory by loading the address in a register, e.g. to load the address of the memory at label MYARRAY into register %l1
```
       sethi   %hi(MYARRAY), %l1
       or      %l1, %lo(MYARRAY), %l1
```

SKILL: You should understand how static and automatic variables in C are related to the corresponding structures in Sparc assembly language.

Revision Date: 2/10/97