SDK • Re: Proper way to get Heap size

Code:

/* Based on GCC ARM embedded samples.   Defines the following symbols for use by code:    __exidx_start    __exidx_end    __etext    __data_start__    __preinit_array_start    __preinit_array_end    __init_array_start    __init_array_end    __fini_array_start    __fini_array_end    __data_end__    __bss_start__    __bss_end__    __end__    end    __HeapLimit    __StackLimit    __StackTop    __stack (== StackTop)*/MEMORY{    FLASH(rx)      : ORIGIN = 0x10000000, LENGTH = 4096k    RAM(rwx)       : ORIGIN = 0x20000000, LENGTH = 252k    RAM_HEAP(rwx)  : ORIGIN = 0x2003F000, LENGTH = 256k    SCRATCH_X(rwx) : ORIGIN = 0x2007F000, LENGTH = 8k    SCRATCH_Y(rwx) : ORIGIN = 0x20081000, LENGTH = 4k}ENTRY(_entry_point)SECTIONS{    .flash_begin : {        __flash_binary_start = .;    } > FLASH    /* The bootrom will enter the image at the point indicated in your       IMAGE_DEF, which is usually the reset handler of your vector table.       The debugger will use the ELF entry point, which is the _entry_point       symbol, and in our case is *different from the bootrom's entry point.*       This is used to go back through the bootrom on debugger launches only,       to perform the same initial flash setup that would be performed on a       cold boot.    */    .text : {        __logical_binary_start = .;        KEEP (*(.vectors))        KEEP (*(.binary_info_header))        __binary_info_header_end = .;        KEEP (*(.embedded_block))        __embedded_block_end = .;        KEEP (*(.reset))        /* TODO revisit this now memset/memcpy/float in ROM */        /* bit of a hack right now to exclude all floating point and time critical (e.g. memset, memcpy) code from         * FLASH ... we will include any thing excluded here in .data below by default */        *(.init)        *libgcc.a:cmse_nonsecure_call.o        *(EXCLUDE_FILE(*libgcc.a: *libc.a:*lib_a-mem*.o *libm.a:) .text*)        *(.fini)        /* Pull all c'tors into .text */        *crtbegin.o(.ctors)        *crtbegin?.o(.ctors)        *(EXCLUDE_FILE(*crtend?.o *crtend.o) .ctors)        *(SORT(.ctors.*))        *(.ctors)        /* Followed by destructors */        *crtbegin.o(.dtors)        *crtbegin?.o(.dtors)        *(EXCLUDE_FILE(*crtend?.o *crtend.o) .dtors)        *(SORT(.dtors.*))        *(.dtors)        . = ALIGN(4);        /* preinit data */        PROVIDE_HIDDEN (__preinit_array_start = .);        KEEP(*(SORT(.preinit_array.*)))        KEEP(*(.preinit_array))        PROVIDE_HIDDEN (__preinit_array_end = .);        . = ALIGN(4);        /* init data */        PROVIDE_HIDDEN (__init_array_start = .);        KEEP(*(SORT(.init_array.*)))        KEEP(*(.init_array))        PROVIDE_HIDDEN (__init_array_end = .);        . = ALIGN(4);        /* finit data */        PROVIDE_HIDDEN (__fini_array_start = .);        *(SORT(.fini_array.*))        *(.fini_array)        PROVIDE_HIDDEN (__fini_array_end = .);        *(.eh_frame*)        . = ALIGN(4);    } > FLASH    /* Note the boot2 section is optional, and should be discarded if there is       no reference to it *inside* the binary, as it is not called by the       bootrom. (The bootrom performs a simple best-effort XIP setup and       leaves it to the binary to do anything more sophisticated.) However       there is still a size limit of 256 bytes, to ensure the boot2 can be       stored in boot RAM.       Really this is a "XIP setup function" -- the name boot2 is historic and       refers to its dual-purpose on RP2040, where it also handled vectoring       from the bootrom into the user image.    */    .boot2 : {        __boot2_start__ = .;        *(.boot2)        __boot2_end__ = .;    } > FLASH    ASSERT(__boot2_end__ - __boot2_start__ <= 256,        "ERROR: Pico second stage bootloader must be no more than 256 bytes in size")    .rodata : {        *(EXCLUDE_FILE(*libgcc.a: *libc.a:*lib_a-mem*.o *libm.a:) .rodata*)        *(.srodata*)        . = ALIGN(4);        *(SORT_BY_ALIGNMENT(SORT_BY_NAME(.flashdata*)))        . = ALIGN(4);    } > FLASH    .ARM.extab :    {        *(.ARM.extab* .gnu.linkonce.armextab.*)    } > FLASH    __exidx_start = .;    .ARM.exidx :    {        *(.ARM.exidx* .gnu.linkonce.armexidx.*)    } > FLASH    __exidx_end = .;    /* Machine inspectable binary information */    . = ALIGN(4);    __binary_info_start = .;    .binary_info :    {        KEEP(*(.binary_info.keep.*))        *(.binary_info.*)    } > FLASH    __binary_info_end = .;    . = ALIGN(4);    .ram_vector_table (NOLOAD): {        *(.ram_vector_table)    } > RAM    .uninitialized_data (NOLOAD): {        . = ALIGN(4);        *(.uninitialized_data*)    } > RAM    .data : {        __data_start__ = .;        *(vtable)        *(.time_critical*)        /* remaining .text and .rodata; i.e. stuff we exclude above because we want it in RAM */        *(.text*)        . = ALIGN(4);        *(.rodata*)        . = ALIGN(4);        *(.data*)        *(.sdata*)        . = ALIGN(4);        *(.after_data.*)        . = ALIGN(4);        /* preinit data */        PROVIDE_HIDDEN (__mutex_array_start = .);        KEEP(*(SORT(.mutex_array.*)))        KEEP(*(.mutex_array))        PROVIDE_HIDDEN (__mutex_array_end = .);        *(.jcr)        . = ALIGN(4);    } > RAM AT> FLASH    .tdata : {        . = ALIGN(4);*(.tdata .tdata.* .gnu.linkonce.td.*)        /* All data end */        __tdata_end = .;    } > RAM AT> FLASH    PROVIDE(__data_end__ = .);    /* __etext is (for backwards compatibility) the name of the .data init source pointer (...) */    __etext = LOADADDR(.data);    .tbss (NOLOAD) : {        . = ALIGN(4);        __bss_start__ = .;        __tls_base = .;        *(.tbss .tbss.* .gnu.linkonce.tb.*)        *(.tcommon)        __tls_end = .;    } > RAM    .bss (NOLOAD) : {        . = ALIGN(4);        __tbss_end = .;        *(SORT_BY_ALIGNMENT(SORT_BY_NAME(.bss*)))        *(COMMON)        PROVIDE(__global_pointer$ = . + 2K);        *(.sbss*)        . = ALIGN(4);        __bss_end__ = .;    } > RAM    .heap (NOLOAD):    {        __end__ = .;        end = __end__;        KEEP(*(.heap*))        /* historically on GCC sbrk was growing past __HeapLimit to __StackLimit, however           to be more compatible, we now set __HeapLimit explicitly to where the end of the heap is */        . = ORIGIN(RAM) + LENGTH(RAM);        __HeapLimit = .;    } > RAM    /* Start and end symbols must be word-aligned */    .scratch_x : {        __scratch_x_start__ = .;        *(.scratch_x.*)        . = ALIGN(4);        __scratch_x_end__ = .;    } > SCRATCH_X AT > FLASH    __scratch_x_source__ = LOADADDR(.scratch_x);    .scratch_y : {        __scratch_y_start__ = .;        *(.scratch_y.*)        . = ALIGN(4);        __scratch_y_end__ = .;    } > SCRATCH_Y AT > FLASH    __scratch_y_source__ = LOADADDR(.scratch_y);    /* .stack*_dummy section doesn't contains any symbols. It is only     * used for linker to calculate size of stack sections, and assign     * values to stack symbols later     *     * stack1 section may be empty/missing if platform_launch_core1 is not used */    /* by default we put core 0 stack at the end of scratch Y, so that if core 1     * stack is not used then all of SCRATCH_X is free.     */    .stack1_dummy (NOLOAD):    {        *(.stack1*)    } > SCRATCH_X    .stack_dummy (NOLOAD):    {        KEEP(*(.stack*))    } > SCRATCH_Y    .flash_end : {        KEEP(*(.embedded_end_block*))        PROVIDE(__flash_binary_end = .);    } > FLASH =0xaa    /* stack limit is poorly named, but historically is maximum heap ptr */    __StackLimit = ORIGIN(RAM) + LENGTH(RAM) + LENGTH(RAM_HEAP);    __StackOneTop = ORIGIN(SCRATCH_Y) + LENGTH(SCRATCH_Y);    __StackTop = ORIGIN(SCRATCH_X) + LENGTH(SCRATCH_X);    __StackOneBottom = __StackOneTop - SIZEOF(.stack1_dummy);    __StackBottom = __StackTop - SIZEOF(.stack_dummy);    PROVIDE(__stack = __StackTop);    /* picolibc and LLVM */    PROVIDE (__heap_start = __end__);    PROVIDE (__heap_end = __HeapLimit);    PROVIDE( __tls_align = MAX(ALIGNOF(.tdata), ALIGNOF(.tbss)) );    PROVIDE( __tls_size_align = (__tls_size + __tls_align - 1) & ~(__tls_align - 1));    PROVIDE( __arm32_tls_tcb_offset = MAX(8, __tls_align) );    /* llvm-libc */    PROVIDE (_end = __end__);    PROVIDE (__llvm_libc_heap_limit = __HeapLimit);    /* Check if data + heap + stack exceeds RAM limit */    ASSERT(__StackLimit >= __HeapLimit, "region RAM overflowed")    ASSERT( __binary_info_header_end - __logical_binary_start <= 1024, "Binary info must be in first 1024 bytes of the binary")    ASSERT( __embedded_block_end - __logical_binary_start <= 4096, "Embedded block must be in first 4096 bytes of the binary")    /* todo assert on extra code */}

Code:

void *UMM_MALLOC_CFG_HEAP_ADDR = (void*)0x2003F000; uint32_t UMM_MALLOC_CFG_HEAP_SIZE = 256 * 1024;