Assembly: Difference between revisions

* Literal values such as 123 are prefixed with '$' (see example above).

* Memory locations have no prefix: mov 123, %eax. Moves the value stored at 123 to eax.

* Registers are prefixed with '%'

* When using a register as a pointer, it is put in parenthesis: mov (%eax), %ebx. Moves the value stored at the pointer stored in eax to ebx.

* When using a statement with memory locations (with no register present), a suffix is needed after the instruction. For example: movl $123, 123. The 'l' (stands for long) is needed to tell the assembler that the values are 32 bits.

* Pointers can be offset by constants by prefixing them: 4(%eax) points to 4+%eax.

* Pointers can be offset by another register by writing them as: (%eax,%ebx) points to %eax+%ebx

* Finally you can combine it all and throw in a scale if you want: 4(%eax,%ebx,2) would be 4+%eax+%ebx*2

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