Added a small example to test PendSV operation,

The example is implemented using a variable stored on the stack and a couple of procedures. Everything is located in the files sch_context_change.h and sch_context_change.s

Author: drowsymike

examples/stm32f4x/app/src/main.c

@@ -19,14 +19,18 @@ void sch_task_init(sch_task_t* task);
 void echo_task_dispatch(sch_task_t* task);
 void echo_task_init(sch_task_t* task);
 
+/*--External objects-----------------------------------------------------------*/
+
+extern volatile uint8_t sch_context_change_interrupt_check;
+
 int main(void)
 {
   HAL_Init();
   SystemClock_Config();
   MX_GPIO_Init();
   MX_USART2_UART_Init();
 
-  sch_task_t first_task;
+  /*sch_task_t first_task;
   sch_task_t second_task;
   sch_task_t echo_data;
   sch_task_t another_system_task;
@@ -37,16 +41,29 @@ int main(void)
   sch_task_create(&second_task, 3, 0, sch_task_dispatch, sch_task_init);
   sch_task_activate(&second_task);
 
-  sch_task_create(&another_system_task, 2, 0, sch_task_dispatch, sch_task_init);
-  sch_task_activate(&second_task);
+  sch_task_create(&another_system_task, 4, 0, sch_task_dispatch, sch_task_init);
+  sch_task_activate(&another_system_task);
 
   sch_task_create(&echo_data, -4, 3, echo_task_dispatch, echo_task_init);
   sch_task_activate(&echo_data);
-  sch_task_run(&echo_data, NULL);
+  sch_task_run(&echo_data, NULL);*/
+
+  /*char buf[40] = {0};
+  snprintf(buf, sizeof(buf), "%d\r\n", sch_find_most_significant_task(sch_preempt_tasks_ready_set));
+  HAL_UART_Transmit(&huart2, (uint8_t*)buf, strlen(buf), HAL_MAX_DELAY);*/
+
+  sch_context_change_interrupt_check = 1;
+  sch_context_change();
+  if (sch_context_change_interrupt_check == 0) 
+  {
+    HAL_UART_Transmit(&huart2, (uint8_t*)"sch_context_change_interrupt_check = 0", \
+    strlen("sch_context_change_interrupt_check = 0"), HAL_MAX_DELAY);
+  } else 
+  {
+    HAL_UART_Transmit(&huart2, (uint8_t*)"sch_context_change_interrupt_check != 0", \
+    strlen("sch_context_change_interrupt_check != 0"), HAL_MAX_DELAY);
+  }
 
-  char buf[40] = {0};
-  snprintf(buf, sizeof(buf), "%d\r\n", sch_find_most_significant_task(sch_system_tasks_ready_set));
-  HAL_UART_Transmit(&huart2, (uint8_t*)buf, strlen(buf), HAL_MAX_DELAY);
 
   while (1)
   {

examples/stm32f4x/platform/startup/startup_stm32f401xe.s

@@ -138,7 +138,7 @@ g_pfnVectors:
   .word  SVC_Handler
   .word  DebugMon_Handler
   .word  0
-  .word  PendSV_Handler
+  .word  sch_context_change_interrupt_handler
   .word  SysTick_Handler
 
   /* External Interrupts */

sch/inc/sch_context_change.h

@@ -7,6 +7,22 @@ extern "C" {
 
 #include "sch_common.h"
 
+/*--Fucntions for debugging the work of interrupt of changing the context----*/
+
+/**
+ * @brief Function for handling the interrupt of command of
+ * changing the context
+ * 
+ * @return void 
+ */
+__WEAK void sch_context_change_interrupt_handler(void);
+
+/*--Objects for defug--------------------------------------------------------*/
+
+extern volatile uint8_t sch_context_change_interrupt_check;
+
+/*---------------------------------------------------------------------------*/
+
 /**
  * @brief Function for finding the most significant task flag
  * in the "registry" what'd been imaged in variable
@@ -22,7 +38,7 @@ uint8_t sch_find_most_significant_task(uint32_t sch_system_tasks_ready_set);
 void sch_context_change(void);
 
 /**
- * @brief Function for planning goddammit
+ * @brief Function for calling the dispatch function
  * 
  */
 void sch_call_dispatch(uint8_t sch_most_significant_task);

sch/port/stm32f4xx/sch_context_change.s

@@ -6,12 +6,20 @@
 .equ __sch_icsr, (__sch_scs_base + __sch_icsr_offset)
 .equ __sch_icsr_pendvset, (1 << 28)
 
-.section .text.sch_context_change
+@ -----------------------------------------------------------------------------
 
-.type sch_context_change, %function
-.type sch_call_dispatch, %function
+.section .data
+.global sch_context_change_interrupt_check
+.align 2
+sch_context_change_interrupt_check:
+    .byte 1
+    .align 2
 
+@ -----------------------------------------------------------------------------
 
+.section .text.sch_context_change
+
+.type sch_call_dispatch, %function
 .global sch_call_dispatch
 sch_call_dispatch:
     ldr r1, =sch_task_registry
@@ -22,10 +30,18 @@ sch_call_dispatch:
     blx r3
     bx lr
 
-
+.type sch_context_change, %function
 .global sch_context_change
 sch_context_change:
     ldr r0, =__sch_icsr
     ldr r1, =__sch_icsr_pendvset
     str r1, [r0]
     bx lr
+
+.type sch_context_change_interrupt_handler, %function
+.global sch_context_change_interrupt_handler
+sch_context_change_interrupt_handler:
+    ldr r0, =sch_context_change_interrupt_check
+    mov r1, #0
+    str r1, [r0]
+    bx lr

sch/port/stm32f4xx/sch_find_most_significant_task.s

@@ -8,6 +8,7 @@ sch_find_most_significant_task:
     cbz r0, .is_data_zero
     clz r0, r0
     rsb r0, r0, #31
+    add r0, #1
     bx lr
 
 .is_data_zero: