fpu with single/double precision - bugfix and extension

- creating new core name Cortex_M7F_DP for a target with a double precision fpu
- adding new core name to arm.py to set compiler/linker flags to a double precision fpu when configured in target.json
- up to now: gcc wrote flag for a double precision fpu -> target with STM32F746 didn't run when using double variables - mcu has only single precision fpu
- changing gcc.py to use single precision for Cortex-M7 und double precision for Cortex_M7F_DP

tested with NUCLEO_F746, NUCLEO_F767 and build.py+make.py and exporting with project.py + compiling/flashing

- iar.py need a similar extention - I didn't change that yet because
  - did not run at the moment - python exception
  - currently worked on in PR #1948

hal/targets.json

@@ -815,7 +815,7 @@
     },
     "NUCLEO_F767ZI": {
         "inherits": ["Target"],
-        "core": "Cortex-M7F",
+        "core": "Cortex-M7F_DP",
         "extra_labels": ["STM", "STM32F7", "STM32F767", "STM32F767ZI"],
         "supported_toolchains": ["ARM", "uARM", "GCC_ARM", "IAR"],
         "default_toolchain": "ARM",

tools/targets.py

@@ -25,6 +25,7 @@ CORE_LABELS = {
     "Cortex-M4F" : ["M4", "CORTEX_M", "RTOS_M4_M7", "LIKE_CORTEX_M4"],
     "Cortex-M7" : ["M7", "CORTEX_M", "RTOS_M4_M7", "LIKE_CORTEX_M7"],
     "Cortex-M7F" : ["M7", "CORTEX_M", "RTOS_M4_M7", "LIKE_CORTEX_M7"],
+    "Cortex-M7F_DP" : ["M7", "CORTEX_M", "RTOS_M4_M7", "LIKE_CORTEX_M7"],
     "Cortex-A9" : ["A9", "CORTEX_A", "LIKE_CORTEX_A9"]
 }
 

tools/toolchains/__init__.py

@@ -219,6 +219,7 @@ class mbedToolchain:
         "Cortex-M4F" : ["__CORTEX_M4", "ARM_MATH_CM4", "__FPU_PRESENT=1", "__CMSIS_RTOS", "__MBED_CMSIS_RTOS_CM"],
         "Cortex-M7" : ["__CORTEX_M7", "ARM_MATH_CM7", "__CMSIS_RTOS", "__MBED_CMSIS_RTOS_CM"],
         "Cortex-M7F" : ["__CORTEX_M7", "ARM_MATH_CM7", "__FPU_PRESENT=1", "__CMSIS_RTOS", "__MBED_CMSIS_RTOS_CM"],
+        "Cortex-M7F_DP" : ["__CORTEX_M7", "ARM_MATH_CM7", "__FPU_PRESENT=1", "__CMSIS_RTOS", "__MBED_CMSIS_RTOS_CM"],
         "Cortex-A9" : ["__CORTEX_A9", "ARM_MATH_CA9", "__FPU_PRESENT", "__CMSIS_RTOS", "__EVAL", "__MBED_CMSIS_RTOS_CA9"],
     }
 

tools/toolchains/arm.py

@@ -51,6 +51,8 @@ class ARM(mbedToolchain):
             cpu = "Cortex-M4.fp"
         elif target.core == "Cortex-M7F":
             cpu = "Cortex-M7.fp.sp"
+        elif target.core == "Cortex-M7F_DP":
+            cpu = "Cortex-M7.fp.dp"
         else:
             cpu = target.core
 

tools/toolchains/gcc.py

@@ -52,6 +52,8 @@ class GCC(mbedToolchain):
             cpu = "cortex-m4"
         elif target.core == "Cortex-M7F":
             cpu = "cortex-m7"
+        elif target.core == "Cortex-M7F_DP":
+            cpu = "cortex-m7"
         else:
             cpu = target.core.lower()
 
@@ -62,7 +64,12 @@ class GCC(mbedToolchain):
         if target.core == "Cortex-M4F":
             self.cpu.append("-mfpu=fpv4-sp-d16")
             self.cpu.append("-mfloat-abi=softfp")
+
         elif target.core == "Cortex-M7F":
+            self.cpu.append("-mfpu=fpv5-sp-d16")
+            self.cpu.append("-mfloat-abi=softfp")
+
+        elif target.core == "Cortex-M7F_DP":
             self.cpu.append("-mfpu=fpv5-d16")
             self.cpu.append("-mfloat-abi=softfp")