cpu/lpc2387: provide ISR_STACKSIZE & thread_isr_stack_start()

Those are needed by MicroPython

cpu/arm7_common/arm7_init.c

@@ -49,6 +49,26 @@ static inline void _init_data(void)
     register unsigned int *dst;
     register unsigned int *end;
 
+#ifdef DEVELHELP
+    /* Fill user stack with canary values up until the current stack pointer */
+    /* Read current stack pointer from CPU register */
+    __asm__ volatile ("mov %[end], sp" : [end] "=r" (end) : : );
+    dst = &__stack_start;
+    while (dst < end) {
+        *(dst++) = STACK_CANARY_WORD;
+    }
+
+    /* fill the interrupt stacks with canary values */
+    extern unsigned int __stack_usr_start;
+    extern unsigned int __stack_end;
+
+    dst = &__stack_usr_start;
+    end = &__stack_end;
+    while (dst < end) {
+        *(dst++) = STACK_CANARY_WORD;
+    }
+#endif
+
     /* initialize data from flash */
     src = &_etext;
     dst = &_srelocate;

cpu/arm7_common/arm_cpu.c

@@ -94,3 +94,43 @@ void thread_print_stack(void)
 
     printf("STACK (%d)= %X \n", i, *s);
 }
+
+void *thread_isr_stack_start(void)
+{
+    extern uintptr_t __stack_irq_start;
+    return (void *)&__stack_irq_start;
+}
+
+void *thread_isr_stack_pointer(void)
+{
+    void *_sp;
+
+    /* If we are not in interrupt mode, the interrupt stack pointer will
+     * always point to the start of the interrupt stack.
+     */
+    if (irq_is_in()) {
+        /* read stack pointer */
+        __asm volatile ("mov %0, r13" : "=r" (_sp) );
+    } else {
+        _sp = thread_isr_stack_start();
+    }
+
+    return _sp;
+}
+
+/* This function returns the number of bytes used on the ISR stack */
+int thread_isr_stack_usage(void)
+{
+    extern uintptr_t __stack_irq_start;
+    extern uintptr_t __stack_irq_size;
+
+    uintptr_t *ptr = &__stack_irq_start - (unsigned) &__stack_irq_size;
+
+    while(((*ptr) == STACK_CANARY_WORD) && (ptr < &__stack_irq_start)) {
+        ++ptr;
+    }
+
+    ptrdiff_t num_used_words = &__stack_irq_start - ptr;
+
+    return num_used_words;
+}

cpu/arm7_common/include/arm_cpu.h

@@ -25,6 +25,16 @@ void cpu_clock_scale(uint32_t source, uint32_t target, uint32_t *prescale);
 
 void arm_reset(void);
 
+/**
+ * @brief Interrupt stack canary value
+ *
+ * @note 0xeafffffe is the ARM machine code equivalent of asm("b #0") or
+ * 'while (1);', i.e. an infinite loop.
+ * @internal
+ */
+#define STACK_CANARY_WORD   (0xEAFFFFFEu)
+
+
 #ifdef __cplusplus
 }
 #endif

cpu/lpc2387/include/cpu_conf.h

@@ -76,6 +76,14 @@ extern "C" {
  */
 #define PUF_SRAM_ATTRIBUTES __attribute__((used, section(".noinit")))
 
+/**
+ * @brief   Stack size used for the exception (ISR) stack
+ * @{
+ */
+extern unsigned __stack_irq_size;
+#define ISR_STACKSIZE                   ((unsigned) &__stack_irq_size)
+/** @} */
+
 #ifdef __cplusplus
 }
 #endif