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71 lines
1.7 KiB
71 lines
1.7 KiB
/// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*- |
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/* |
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keep track of available memory on AVR |
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*/ |
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/* |
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* note that we use a 32 bit sentinel to reduce the chance |
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* of false positives with uninitialised stack variables |
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*/ |
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#include <AP_HAL.h> |
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#include <stdlib.h> |
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#include <stdint.h> |
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#if (CONFIG_HAL_BOARD == HAL_BOARD_APM1 || CONFIG_HAL_BOARD == HAL_BOARD_APM2) |
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static const uint32_t *stack_low; |
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extern unsigned __brkval; |
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#define STACK_OFFSET 2 |
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#define SENTINEL 0x28021967 |
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/* |
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* return the current stack pointer |
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*/ |
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static __attribute__((noinline)) const uint32_t *current_stackptr(void) |
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{ |
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return (const uint32_t *)__builtin_frame_address(0); |
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} |
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/* |
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* this can be added in deeply nested code to ensure we catch |
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* deep stack usage. It should be caught by the sentinel, but this |
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* is an added protection |
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*/ |
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static void memcheck_update_stackptr(void) |
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{ |
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if (current_stackptr() < stack_low) { |
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uintptr_t s = (uintptr_t)(current_stackptr() - STACK_OFFSET); |
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stack_low = (uint32_t *)(s & ~3); |
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} |
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} |
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/* |
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* initialise memcheck, setting up the sentinels |
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*/ |
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void memcheck_init(void) |
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{ |
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uint32_t *p; |
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free(malloc(1)); // ensure heap is initialised |
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stack_low = current_stackptr(); |
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memcheck_update_stackptr(); |
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for (p=(uint32_t *)(stack_low-1); p>(uint32_t *)__brkval; p--) { |
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*p = SENTINEL; |
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} |
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} |
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/* |
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* this returns the real amount of free memory by looking for |
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* overwrites of the stack sentinel values |
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*/ |
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unsigned memcheck_available_memory(void) |
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{ |
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memcheck_update_stackptr(); |
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while (*stack_low != SENTINEL && stack_low > (const uint32_t *)__brkval) { |
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stack_low--; |
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} |
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return (uintptr_t)(stack_low) - __brkval; |
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} |
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#endif // CONFIG_HAL_BOARD
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