| Syntax | Meaning |
|---|---|
| .data | Introduces the data (i.e. global variables) section of the program. |
| .text | Introduces the text (i.e. code) section of the program. |
Directives which can only be used in a .data section of an assembly language program file:
| Syntax | Meaning | Example |
|---|---|---|
| .asciiz "characters" | characters will be stored in memory as a zero byte terminated string constant. | .asciiz "Hello world" |
| .space number | number of bytes is reserved in memory. | .space 400 |
| .word number | The 32-bit number number is stored in memory. | .word 1234 |
| Syntax | Meaning |
|---|---|
| identifier: | identifier is associated with the address of the item following the label |
Convenient ways to refer to addresses. Can be used in .data and .text sections.
For global variables:
The address associated with a label of a global variable can be interpreted
directly as an offset because it is as though we start addressing the global
variables from address 0. They are actually addressed starting from the address
that is held in the global pointer register $gp. However the actual
address is not known until the program starts executing. We do know what the
offset should be however.
For instructions:
The address associated with a label of an instruction is used to calculate the
number of instructions to branch forwards or backwards by in a branch
instruction. It is used to calculate the instruction number to jump
instruction.
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