| 1 | /** |
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| 2 | ****************************************************************************** |
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| 3 | * @file sysmem.c |
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| 4 | * @author Generated by STM32CubeMX |
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| 5 | * @brief System Memory calls file |
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| 6 | * |
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| 7 | * For more information about which C functions |
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| 8 | * need which of these lowlevel functions |
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| 9 | * please consult the Newlib or Picolibc libc manual |
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| 10 | ****************************************************************************** |
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| 11 | * @attention |
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| 12 | * |
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| 13 | * Copyright (c) 2025 STMicroelectronics. |
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| 14 | * All rights reserved. |
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| 15 | * |
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| 16 | * This software is licensed under terms that can be found in the LICENSE file |
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| 17 | * in the root directory of this software component. |
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| 18 | * If no LICENSE file comes with this software, it is provided AS-IS. |
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| 19 | * |
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| 20 | ****************************************************************************** |
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| 21 | */ |
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| 22 | |
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| 23 | /* Includes */ |
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| 24 | #include <errno.h> |
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| 25 | #include <stdint.h> |
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| 26 | #include <stddef.h> |
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| 27 | |
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| 28 | /** |
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| 29 | * Pointer to the current high watermark of the heap usage |
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| 30 | */ |
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| 31 | static uint8_t *__sbrk_heap_end = NULL; |
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| 32 | |
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| 33 | /** |
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| 34 | * @brief _sbrk() allocates memory to the newlib heap and is used by malloc |
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| 35 | * and others from the C library |
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| 36 | * |
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| 37 | * @verbatim |
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| 38 | * ############################################################################ |
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| 39 | * # .data # .bss # newlib heap # MSP stack # |
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| 40 | * # # # # Reserved by _Min_Stack_Size # |
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| 41 | * ############################################################################ |
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| 42 | * ^-- RAM start ^-- _end _estack, RAM end --^ |
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| 43 | * @endverbatim |
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| 44 | * |
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| 45 | * This implementation starts allocating at the '_end' linker symbol |
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| 46 | * The '_Min_Stack_Size' linker symbol reserves a memory for the MSP stack |
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| 47 | * The implementation considers '_estack' linker symbol to be RAM end |
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| 48 | * NOTE: If the MSP stack, at any point during execution, grows larger than the |
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| 49 | * reserved size, please increase the '_Min_Stack_Size'. |
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| 50 | * |
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| 51 | * @param incr Memory size |
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| 52 | * @return Pointer to allocated memory |
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| 53 | */ |
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| 54 | void *_sbrk(ptrdiff_t incr) |
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| 55 | { |
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| 56 | extern uint8_t _end; /* Symbol defined in the linker script */ |
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| 57 | extern uint8_t _estack; /* Symbol defined in the linker script */ |
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| 58 | extern uint32_t _Min_Stack_Size; /* Symbol defined in the linker script */ |
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| 59 | const uint32_t stack_limit = (uint32_t)&_estack - (uint32_t)&_Min_Stack_Size; |
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| 60 | const uint8_t *max_heap = (uint8_t *)stack_limit; |
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| 61 | uint8_t *prev_heap_end; |
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| 62 | |
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| 63 | /* Initialize heap end at first call */ |
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| 64 | if (NULL == __sbrk_heap_end) |
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| 65 | { |
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| 66 | __sbrk_heap_end = &_end; |
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| 67 | } |
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| 68 | |
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| 69 | /* Protect heap from growing into the reserved MSP stack */ |
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| 70 | if (__sbrk_heap_end + incr > max_heap) |
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| 71 | { |
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| 72 | errno = ENOMEM; |
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| 73 | return (void *)-1; |
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| 74 | } |
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| 75 | |
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| 76 | prev_heap_end = __sbrk_heap_end; |
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| 77 | __sbrk_heap_end += incr; |
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| 78 | |
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| 79 | return (void *)prev_heap_end; |
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| 80 | } |
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| 81 | |
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| 82 | #if defined(__PICOLIBC__) |
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| 83 | // Picolibc expects syscalls without the leading underscore. |
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| 84 | // This creates a strong alias so that |
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| 85 | // calls to `sbrk()` are resolved to our `_sbrk()` implementation. |
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| 86 | __strong_reference(_sbrk, sbrk); |
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| 87 | #endif |
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