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| | | PicPuter 2.0 : Appendix D : Vectors |
There are 4 vectors currently in PicPuter. One is used for user IRQ (interupt) routines and the other 3 are used for custom statements.
The vectors are located at $1000 - $1008 if memory serves me, If you are going to use vectors email me to put up the memory adresses up here.
User Statements |
There are 3 user statements USR , USR2 , and USRM . These statements call an assembler routine at a specific address. They are ment so users can extend the language with there own commands.
| IRQ Vector |
To simplify PicPuter, only a single IRQ Vector is provided. The user must figure out which IRQ ocured by checking the necessary interupt flags.
If an interupt mask is enabled, the PWM will begin jitter. It is better not to set the interupt mask, but just use the interupt flag. The IRQ vector is called every __TICK__ if
CONFIGURATOR bit 14 is set. It is best just to do your processing during the __TICK__ interupt to prevent jitter.
However, you can set your interupt mask. PicPuter will call the irq vector when your irq occurs and during a __TICK__ interval.
Interupts are a special context, you can not use the hardware stack durring an interupt. (no calls) You do not need to worry about backing up any registers. When you are finished return controll to the kernel by the statement goto $0003, but make sure the upper address bits are set. |
