Provide 'end' symbol for C std library

This replaces the previous definition of 'end' that was in error (it was an empty void void function). This is a (more) appropriate solution that provides a memory address that is computed from the linker script. 'end' allows malloc + friends to operate correctly. This in turn allows some other important functions to work, like Arduino Strings and stdlib 'rand()'

Author: oclyke

cores/arduino/ard_sup/main.cpp

@@ -12,10 +12,7 @@ extern "C" void _init(void)
 {
   // Empty definition to resolve linker error within '__libc_init_array'
 }
-extern "C" void end(void)
-{
-  // Empty definition to satisfy linker error in '_sbrk'
-}
+void *__dso_handle; // providing the __dso_handle symbol manually. Todo: more research for the *correct* solution
 
 extern "C" int main(void)
 {

variants/SparkFun_Artemis/linker_scripts/gcc/ambiq_sbl_app.ld

@@ -66,5 +66,13 @@ SECTIONS
         _ebss = .;
     } > SRAM
 
+    .heap (COPY):
+	{
+		__end__ = .;
+		PROVIDE(end = .);
+		*(.heap*)
+		__HeapLimit = .;
+	} > SRAM
+
     .ARM.attributes 0 : { *(.ARM.attributes) }
 }

variants/SparkFun_Artemis/linker_scripts/gcc/artemis_sbl_svl_app.ld

@@ -66,5 +66,15 @@ SECTIONS
         _ebss = .;
     } > SRAM
 
+    .heap (COPY):
+	{
+		__end__ = .;
+		PROVIDE(end = .);
+		*(.heap*)
+		__HeapLimit = .;
+	} > SRAM
+
+    /* TODO: Collision Checking (at link time) */
+
     .ARM.attributes 0 : { *(.ARM.attributes) }
 }

variants/SparkFun_BlackBoard_Artemis/linker_scripts/gcc/ambiq_sbl_app.ld

@@ -66,5 +66,13 @@ SECTIONS
         _ebss = .;
     } > SRAM
 
+    .heap (COPY):
+	{
+		__end__ = .;
+		PROVIDE(end = .);
+		*(.heap*)
+		__HeapLimit = .;
+	} > SRAM
+
     .ARM.attributes 0 : { *(.ARM.attributes) }
 }

variants/SparkFun_BlackBoard_Artemis/linker_scripts/gcc/artemis_sbl_svl_app.ld

@@ -66,5 +66,15 @@ SECTIONS
         _ebss = .;
     } > SRAM
 
+    .heap (COPY):
+	{
+		__end__ = .;
+		PROVIDE(end = .);
+		*(.heap*)
+		__HeapLimit = .;
+	} > SRAM
+
+    /* TODO: Collision Checking (at link time) */
+
     .ARM.attributes 0 : { *(.ARM.attributes) }
 }

variants/SparkFun_BlackBoard_Artemis_Mega/linker_scripts/gcc/ambiq_sbl_app.ld

@@ -66,5 +66,13 @@ SECTIONS
         _ebss = .;
     } > SRAM
 
+    .heap (COPY):
+	{
+		__end__ = .;
+		PROVIDE(end = .);
+		*(.heap*)
+		__HeapLimit = .;
+	} > SRAM
+
     .ARM.attributes 0 : { *(.ARM.attributes) }
 }

variants/SparkFun_BlackBoard_Artemis_Mega/linker_scripts/gcc/artemis_sbl_svl_app.ld

@@ -66,5 +66,15 @@ SECTIONS
         _ebss = .;
     } > SRAM
 
+    .heap (COPY):
+	{
+		__end__ = .;
+		PROVIDE(end = .);
+		*(.heap*)
+		__HeapLimit = .;
+	} > SRAM
+
+    /* TODO: Collision Checking (at link time) */
+
     .ARM.attributes 0 : { *(.ARM.attributes) }
 }

variants/SparkFun_BlackBoard_Artemis_Nano/linker_scripts/gcc/ambiq_sbl_app.ld

@@ -66,5 +66,13 @@ SECTIONS
         _ebss = .;
     } > SRAM
 
+    .heap (COPY):
+	{
+		__end__ = .;
+		PROVIDE(end = .);
+		*(.heap*)
+		__HeapLimit = .;
+	} > SRAM
+
     .ARM.attributes 0 : { *(.ARM.attributes) }
 }

variants/SparkFun_BlackBoard_Artemis_Nano/linker_scripts/gcc/artemis_sbl_svl_app.ld

@@ -66,5 +66,15 @@ SECTIONS
         _ebss = .;
     } > SRAM
 
+    .heap (COPY):
+	{
+		__end__ = .;
+		PROVIDE(end = .);
+		*(.heap*)
+		__HeapLimit = .;
+	} > SRAM
+
+    /* TODO: Collision Checking (at link time) */
+
     .ARM.attributes 0 : { *(.ARM.attributes) }
 }

variants/SparkFun_Edge/linker_scripts/gcc/ambiq_sbl_app.ld

@@ -66,5 +66,13 @@ SECTIONS
         _ebss = .;
     } > SRAM
 
+    .heap (COPY):
+	{
+		__end__ = .;
+		PROVIDE(end = .);
+		*(.heap*)
+		__HeapLimit = .;
+	} > SRAM
+
     .ARM.attributes 0 : { *(.ARM.attributes) }
 }