Add support of heap memory split between 2-RAM banks.

Please note the heap address of the both the banks must not be contigious else
GCC considers it to be single memory bank and does allocation across the banks,
which might result into hard-fault

platform/mbed_retarget.cpp

@@ -1240,6 +1240,41 @@ extern "C" WEAK void __cxa_pure_virtual(void)
 // SP.  This make it compatible with RTX RTOS thread stacks.
 #if defined(TOOLCHAIN_GCC_ARM)
 
+#if defined(MBED_SPLIT_HEAP)
+
+extern uint32_t __mbed_sbrk_start;
+extern uint32_t __mbed_krbs_start;
+extern uint32_t __mbed_sbrk_start_0;
+extern uint32_t __mbed_krbs_start_0;
+
+extern "C" WEAK caddr_t _sbrk(int incr)
+{
+    static uint32_t heap = (uint32_t) &__mbed_sbrk_start_0;
+    static bool once = true;
+    uint32_t prev_heap = heap;
+    uint32_t new_heap = heap + incr;
+
+    /**
+     * If the new address is outside the first region, start allocating from the second region.
+     */
+    if (once && (new_heap > (uint32_t) &__mbed_krbs_start_0)) {
+        once = false;
+        prev_heap = (uint32_t) &__mbed_sbrk_start;
+        new_heap = prev_heap + incr;
+    } else if (new_heap > (uint32_t) &__mbed_krbs_start) {
+        /**
+        * If the new address is outside the second region, return out-of-memory.
+        */
+        errno = ENOMEM;
+        return (caddr_t) - 1;
+    }
+
+    heap = new_heap;
+    return (caddr_t) prev_heap;
+}
+
+#else
+
 extern "C" uint32_t         __end__;
 extern "C" uint32_t         __HeapLimit;
 
@@ -1264,6 +1299,7 @@ extern "C" WEAK caddr_t _sbrk(int incr)
     return (caddr_t) prev_heap;
 }
 #endif
+#endif
 
 #if defined(TOOLCHAIN_GCC_ARM)
 extern "C" void _exit(int return_code)

targets/TARGET_STM/TARGET_STM32L4/l4_retarget.c

@@ -1,78 +0,0 @@
-/**
-  ******************************************************************************
-  * @file    l4_retarget.c
- * @author   MCD Application Team
-  * @brief   CMSIS Cortex-M4 Core Peripheral Access Layer Source File for STM32L475xG
-  ******************************************************************************
-  * @attention
-  *
-  * <h2><center>&copy; COPYRIGHT(c) 2018 STMicroelectronics</center></h2>
-  *
-  * Redistribution and use in source and binary forms, with or without modification,
-  * are permitted provided that the following conditions are met:
-  *   1. Redistributions of source code must retain the above copyright notice,
-  *      this list of conditions and the following disclaimer.
-  *   2. Redistributions in binary form must reproduce the above copyright notice,
-  *      this list of conditions and the following disclaimer in the documentation
-  *      and/or other materials provided with the distribution.
-  *   3. Neither the name of STMicroelectronics nor the names of its contributors
-  *      may be used to endorse or promote products derived from this software
-  *      without specific prior written permission.
-  *
-  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
-  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
-  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
-  * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
-  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
-  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
-  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
-  * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
-  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
-  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-  *
-  ******************************************************************************
-  */
-#if (defined(TWO_RAM_REGIONS) && defined(__GNUC__) && !defined(__CC_ARM) && !defined(__ARMCC_VERSION))
-#include <stdbool.h>
-#include <errno.h>
-#include "stm32l4xx.h"
-extern uint32_t __mbed_sbrk_start;
-extern uint32_t __mbed_krbs_start;
-extern uint32_t __mbed_sbrk_start_0;
-extern uint32_t __mbed_krbs_start_0;
-
-/**
- * The default implementation of _sbrk() (in platform/mbed_retarget.cpp) for GCC_ARM only supports one region.
- * This implementation supports two regions by continuing the allocation to the second region after the first
- * one is full.
- * Define __wrap__sbrk() to override the default _sbrk(). It is expected to get called through gcc
- * hooking mechanism ('-Wl,--wrap,_sbrk') or in _sbrk().
- */
-void *__wrap__sbrk(int incr)
-{
-    static uint32_t heap_ind = (uint32_t) &__mbed_sbrk_start_0;
-    static bool once = true;
-    uint32_t heap_ind_old = heap_ind;
-    uint32_t heap_ind_new = heap_ind_old + incr;
-
-    /**
-     * If the new address is outside the first region, start allocating from the second region.
-     */
-    if (once && (heap_ind_new >= (uint32_t)&__mbed_krbs_start_0)) {
-        once = false;
-        heap_ind_old = (uint32_t)&__mbed_sbrk_start;
-        heap_ind_new = heap_ind_old + incr;
-    /**
-     * If the new address is outside the second region, return out-of-memory.
-     */
-    } else if (heap_ind_new >= (uint32_t)&__mbed_krbs_start) {
-        errno = ENOMEM;
-        return (void *) - 1;
-    }
-
-    heap_ind = heap_ind_new;
-
-    return (void *) heap_ind_old;
-}
-#endif /* GCC_ARM toolchain && TWO_RAM_REGIONS*/
-

targets/targets.json

@@ -4147,7 +4147,8 @@
         "detect_code": ["0764"],
         "macros_add": [
             "MBED_TICKLESS",
-            "USBHOST_OTHER"
+            "USBHOST_OTHER",
+            "MBED_SPLIT_HEAP"
         ],
         "device_has_add": [
             "ANALOGOUT",
@@ -4178,7 +4179,7 @@
             }
         },
         "detect_code": ["0468"],
-        "macros_add": ["USBHOST_OTHER", "TWO_RAM_REGIONS"],
+        "macros_add": ["USBHOST_OTHER", "MBED_SPLIT_HEAP"],
         "device_has_add": [
             "ANALOGOUT",
             "CAN",