C6x programming (1/3) C6x code development Programming levels C - - PowerPoint PPT Presentation

C6x programming (1/3)

C6x code development

Programming levels

◼ C (for the C/C++ compiler) ◼ Linear assembly (for the assembly optimizer)

units and registers may be specified

◼ Assembly (for the assembler)

units and registers are specified (* non parallel assembly: instruction latency is taken into account) * parallel assembly: instruction latency is taken into account + instructions are put in parallel

Pipeline

◼ C30:

| fetch | decode | read | execute |

◼ C5x:

| prefetch+fetch | decode | access+read | execute |

◼ C6x:

| 4 phases | 2 phases | 1 to 5 phases |

Pipeline

(just to have an idea

• n what happens in

the various phases…)

◼ The number of execute phases (E1... E5) depends on the

instruction

Pipeline and branches

◼ The branch target is fetched during E1 (only one E

phase is used), so

◼ the branch is delayed by 5 cycles [spru189e]