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资源说明：contr is a library designed to allow a reactive programming style to be used in C for embedded applications.
contr - A continuation based reactive programming library in C for real-time embedded applications
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__contr__ is a library designed to allow a reactive programming style to be used in C for embedded applications. It was originally written to make writing a simple timer running on TI's MSP430 LaunchPad (to control a pump for my aeroponic garden) more fun.
USE
---
Define indices into the contexts array for each unique reactive value.
enum reactives {
R_TIME = 0,
R_BUTTON
};
In the code where you want to use these values, get the stack pointer with `GET_SP`, and store it.
word *start;
GET_SP(start);
Call the `r_{type}()` function, passing `start`, `NULL`, the reactive value's index, and the initial value. The control flow of your program must call the `r_{type}()` functions before calling the corresponding `r_call_{type}()` functions for them to work correctly.
t = r_uint16_t(start, NULL, R_TIME, 0);
If you want to evaluate a block of code only when the reactive value changes, wrap it in a `BLOCK`. Make sure that any variables you want to stay updated are not on the stack. (e.g. static)
static uint16_t x;
BLOCK(a_block) {
t = r_uint16_t(start, a_block, R_TIME, 0);
x = computationally_expensive_function(t);
}
In your interrupt handler, call `r_call_{type}()` with the reactive value's index and the new value.
__attribute__((interrupt(TIMERA0_VECTOR)))
void timer_isr() {
static uint16_t timer_cnt = 0;
r_call_uint16_t(R_TIME, timer_cnt++);
}
Make sure there are enough contexts and stack storage for your program by defining the `MAX_CONTEXTS` and `MAX_STACK_SPACE` appropriately, by passing `-DMAX_CONTEXTS=x` and `-DMAX_STACK_SPACE=y` to gcc when compiling the library. If you define `DEBUG`, __contr__ will warn you if you don't have enough stack space. See the Makefile for examples.
Now you're ready to use __contr__ in your program!
Building the examples
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Run `make clean` first.
* __test__: `make ARCH=X86 test` or `make ARCH=X86_64 test`
* __test-msp430__ (for MSP430 LaunchPad): `make ARCH=MSP430 test-msp430.elf`
* __pump__ (for MSP430 LaunchPad): `make ARCH=MSP430 pump.elf`
* __exp\_board__ (for FRAM Experimenter's Board): `make ARCH=MSP430 exp\_board.elf
Adding Architectures
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The `GET_SP` and `SET_SP` functions need to be defined in assembly. Also, if the stack does not grow down (towards a lower address), more work will need to be done. I intend to add support for the AVR ATmega family of microprocessors.
Credits
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The method of using continuations in C was inspired by Dan Piponi's (sigfpe) [Continuations in C](http://homepage.mac.com/sigfpe/Computing/continuations.html).
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