On Jul 5, 2006, at 2:24 AM, Frigging wrote:
Hi,
by the way I'm interesting about tinyos 2.x
you've had wrote:
"Interrupts, however, can preempt tasks. All code that an interrupt
handler
calls must be async. The hardware takes care of pushing some
context on the
stack, and the compiler takes care of spilling registers to memory.
The
question of when interrupts can be handled or not (interrupt
preemption,
etc.) depends on 2 things: the chip architecture and whether the
code has
disabled interrupts or adjusted the interrupt priority level."
but this means that asyc function could preempt an other async
function?
However if an interrupt handler can call only async function, maybe
it's
possible (if the chip architecture and whether the code has not
disabled
interrupts or adjusted the interrupt priority level) preempt an
other async
function. I think so, because I read your paper "TinyOS
Programming" at page
39, and I understand that since "In this example, c can
(theoretically)
preempt a ...", for me this means that async function can preempt
task and
async function. While sync function is running (no-blocking), are
interrupts
disabled? or is there a interrupts queue?
In tinyos 2.x where is interrupt priority level handled ?
You're asking about hardware at this point, rather than TinyOS.
Some interrupt handlers have interrupts disabled during their
execution (e.g., the I2C/two-wire interrupt on the atm128 basically
requires they be disabled in order to work properly). Others keep
interrupts enabled during their execution. IPLs are generally
hardware, not software, mechanisms. In microcontrollers, priority
levels generally indicate execution order, but the MCU does not
support conditional disabling in the way that microprocessors do.
Phil
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