Add configurable FPU support

Author: kar-rahul-aws

portable/GCC/ARM_CRx_No_GIC/port.c

@@ -28,6 +28,7 @@
 
 /* Standard includes. */
 #include <stdlib.h>
+#include <string.h>
 
 /* Scheduler includes. */
 #include "FreeRTOS.h"
@@ -80,10 +81,16 @@
     #define portTASK_RETURN_ADDRESS    prvTaskExitError
 #endif
 
+/* The space on the stack required to hold the FPU registers. */
+#if ( configFPU_D32 == 1 )
+    #define portFPU_REGISTER_WORDS     ( ( 32 * 2 ) + 1 ) /* D0-D31 and FPSCR. */
+#else
+    #define portFPU_REGISTER_WORDS     ( ( 16 * 2 ) + 1 ) /* D0-D15 and FPSCR. */
+#endif
 /*-----------------------------------------------------------*/
 
 /*
- * These functions are necessarily written in assembly code, so are implemented 
+ * These functions are necessarily written in assembly code, so are implemented
  * in portASM.S.
  */
 extern void vPortRestoreTaskContext( void );
@@ -186,12 +193,33 @@ StackType_t * pxPortInitialiseStack( StackType_t * pxTopOfStack,
     /* The task will start with a critical nesting count of 0 as interrupts are
      * enabled. */
     *pxTopOfStack = portNO_CRITICAL_NESTING;
-    pxTopOfStack--;
 
-    /* The task will start without a floating point context.  A task that uses
-     * the floating point hardware must call vPortTaskUsesFPU() before executing
-     * any floating point instructions. */
-    *pxTopOfStack = portNO_FLOATING_POINT_CONTEXT;
+    #if ( configUSE_TASK_FPU_SUPPORT == 1 )
+    {
+        /* The task will start without a floating point context.  A task that uses
+         * the floating point hardware must call vPortTaskUsesFPU() before executing
+         * any floating point instructions. */
+        pxTopOfStack--;
+        *pxTopOfStack = portNO_FLOATING_POINT_CONTEXT;
+    }
+    #elif ( configUSE_TASK_FPU_SUPPORT == 2 )
+    {
+        /* The task will start with a floating point context.  Leave enough
+         * space for the registers - and ensure they are initialised to 0. */
+        pxTopOfStack -= portFPU_REGISTER_WORDS;
+        memset( pxTopOfStack, 0x00, portFPU_REGISTER_WORDS * sizeof( StackType_t ) );
+
+        /* Initialise the slot containing ulPortTaskHasFPUContext to true as
+         * the task starts with a floating point context. */
+        pxTopOfStack--;
+        *pxTopOfStack = pdTRUE;
+        ulPortTaskHasFPUContext = pdTRUE;
+    }
+    #else
+    {
+        #error "Invalid configUSE_TASK_FPU_SUPPORT value - configUSE_TASK_FPU_SUPPORT must be set to 1, 2, or left undefined."
+    }
+    #endif /* if ( configUSE_TASK_FPU_SUPPORT == 1 ) */
 
     return pxTopOfStack;
 }
@@ -312,13 +340,17 @@ void FreeRTOS_Tick_Handler( void )
 }
 /*-----------------------------------------------------------*/
 
-void vPortTaskUsesFPU( void )
-{
-    /* A task is registering the fact that it needs an FPU context.  Set the
-     * FPU flag (which is saved as part of the task context). */
-    ulPortTaskHasFPUContext = pdTRUE;
+#if ( configUSE_TASK_FPU_SUPPORT != 2 )
 
-    /* Initialise the floating point status register. */
-    vPortInitialiseFPSCR();
-}
+    void vPortTaskUsesFPU( void )
+    {
+        /* A task is registering the fact that it needs an FPU context.  Set the
+         * FPU flag (which is saved as part of the task context). */
+        ulPortTaskHasFPUContext = pdTRUE;
+
+        /* Initialise the floating point status register. */
+        vPortInitialiseFPSCR();
+    }
+
+#endif /* configUSE_TASK_FPU_SUPPORT */
 /*-----------------------------------------------------------*/

portable/GCC/ARM_CRx_No_GIC/portmacro.h

@@ -105,9 +105,6 @@ extern void vPortEnableInterrupts( void );
 extern void vPortDisableInterrupts( void );
 extern uint32_t ulPortSetInterruptMaskFromISR( void );
 
-/* The I bit within the CPSR. */
-#define portINTERRUPT_ENABLE_BIT    ( 1 << 7 )
-
 /* In the absence of a priority mask register, these functions and macros
  * globally enable and disable interrupts. */
 #define portENTER_CRITICAL()                    vPortEnterCritical();
@@ -135,9 +132,18 @@ extern uint32_t ulPortSetInterruptMaskFromISR( void );
  * handler for whichever peripheral is used to generate the RTOS tick. */
 void FreeRTOS_Tick_Handler( void );
 
-/* Any task that uses the floating point unit MUST call vPortTaskUsesFPU()
- * before any floating point instructions are executed. */
-void vPortTaskUsesFPU( void );
+/* If configUSE_TASK_FPU_SUPPORT is set to 1 (or left undefined) then tasks are
+ * created without an FPU context and must call vPortTaskUsesFPU() to give
+ * themselves an FPU context before using any FPU instructions.  If
+ * configUSE_TASK_FPU_SUPPORT is set to 2 then all tasks will have an FPU
+ * context by default. */
+#if ( configUSE_TASK_FPU_SUPPORT != 2 )
+    void vPortTaskUsesFPU( void );
+#else
+    /* Each task has an FPU context already, so define this function away to
+     * nothing to prevent it from being called accidentally. */
+    #define vPortTaskUsesFPU()
+#endif
 #define portTASK_USES_FLOATING_POINT()    vPortTaskUsesFPU()
 
 #define portLOWEST_INTERRUPT_PRIORITY           ( ( ( uint32_t ) configUNIQUE_INTERRUPT_PRIORITIES ) - 1UL )