RFA: V850: Separate DATA and HEAP memory areas

[Nick Clifton]

Hi Jeff,

  I would like permission to apply the patch below to the V850 version
  of the sbrk() function in newlib and libgloss.  It does two things.
  Firstly it tidies up the code.  Secondly it changes the start of the
  heap to be based on the symbol "heap_start" rather than the symbol
  "end".  The importance of the second change is that it allows the heap
  to be placed somewhere other than at the end of data.  This means that
  on a V850 board with two separate banks of memory, for example, the
  stack and heap can be in one bank and the data in another.  Eg:

    MEMORY
    {
      ROM       : ORIGIN = 0x00001000, LENGTH = 0x001ff000 /* 2Mb */
      RAM2 (w)  : ORIGIN = 0xfebf0000, LENGTH = 0x00010000 /* 64k */
      STACK (w) : ORIGIN = 0xfebffff0, LENGTH = 16         /* Top of RAM2 */
      RAM (w)   : ORIGIN = 0xfedf0000, LENGTH = 0x00010000 /* 64k */
    }

    SECTIONS
    {
      .text :
      {
        *(.text)
      } >ROM =0

      .data :
      {
        PROVIDE (__datastart = .);
        *(.data)
      } >RAM AT>ROM

      .bss :
      {
	*(.bss)
	PROVIDE (end = .);
      } >RAM
  
      .heap :
      {
	KEEP (*(.heap))
	PROVIDE (_heap_start = .);
      } >RAM2
	
      .stack :
      {
	__stack = .;
	KEEP ( *(.stack) )
      } > STACK
    } 

  Ok to apply ?

Cheers
  Nick

newlib/ChangeLog
2011-05-23  Nick Clifton  <nickc@redhat.com>

	* libc/sys/sysnecv850/sbrk.c (_sbrk): Tidy code.
        Base start of heap on the "heap_start" symbol.

libgloss/ChangeLog
2011-05-23  Nick Clifton  <nickc@redhat.com>

	* v8500/sbrk.c (_sbrk): Tidy code.
        Base start of heap on the "heap_start" symbol.

  
Index: newlib/libc/sys/sysnecv850/sbrk.c
===================================================================
RCS file: /cvs/src/src/newlib/libc/sys/sysnecv850/sbrk.c,v
retrieving revision 1.1.1.1
diff -u -3 -p -r1.1.1.1 sbrk.c
--- newlib/libc/sys/sysnecv850/sbrk.c	17 Feb 2000 19:39:50 -0000	1.1.1.1
+++ newlib/libc/sys/sysnecv850/sbrk.c	23 May 2011 09:38:00 -0000
@@ -3,34 +3,27 @@
 #include <sys/stat.h>
 #include "sys/syscall.h"
 
-int errno;
-
-int __trap0 (int function, int p1, int p2, int p3);
-
-#define TRAP0(f, p1, p2, p3) __trap0(f, (int)(p1), (int)(p2), (int)(p3))
-
 caddr_t
 _sbrk (int incr)
 {
-  extern char end;		/* Defined by the linker */
-  static char *heap_end;
-  char *prev_heap_end;
-#if 0
-  char *sp = (char *)stack_ptr;
-#else
-  char *sp = (char *)&sp;
-#endif
+  extern char   heap_start;	/* Defined by the linker script.  */
+  static char * heap_end = NULL;
+  char *        prev_heap_end;
+  char *        sp = (char *) & sp;
+
+  if (heap_end == NULL)
+    heap_end = & heap_start;
 
-  if (heap_end == 0)
-    {
-      heap_end = &end;
-    }
   prev_heap_end = heap_end;
+
   if (heap_end + incr > sp)
     {
-      _write (1, "Heap and stack collision\n", 25);
+#define MESSAGE "Heap and stack collision\n"
+      _write (1, MESSAGE, sizeof MESSAGE);
       abort ();
     }
+
   heap_end += incr;
+
   return (caddr_t) prev_heap_end;
 }
Index: libgloss/v850/sbrk.c
===================================================================
RCS file: /cvs/src/src/libgloss/v850/sbrk.c,v
retrieving revision 1.1
diff -u -3 -p -r1.1 sbrk.c
--- libgloss/v850/sbrk.c	23 Jul 2010 17:52:37 -0000	1.1
+++ libgloss/v850/sbrk.c	23 May 2011 09:38:00 -0000
@@ -3,34 +3,27 @@
 #include <sys/stat.h>
 #include "sys/syscall.h"
 
-int errno;
-
-int __trap0 (int function, int p1, int p2, int p3);
-
-#define TRAP0(f, p1, p2, p3) __trap0(f, (int)(p1), (int)(p2), (int)(p3))
-
 caddr_t
 _sbrk (int incr)
 {
-  extern char end;		/* Defined by the linker */
-  static char *heap_end;
-  char *prev_heap_end;
-#if 0
-  char *sp = (char *)stack_ptr;
-#else
-  char *sp = (char *)&sp;
-#endif
+  extern char   heap_start;		/* Defined by the linker script. */
+  static char * heap_end = NULL;
+  char *        prev_heap_end;
+  char *        sp = (char *) & sp;
+
+  if (heap_end == NULL)
+    heap_end = & heap_start;
 
-  if (heap_end == 0)
-    {
-      heap_end = &end;
-    }
   prev_heap_end = heap_end;
+
   if (heap_end + incr > sp)
     {
-      _write (1, "Heap and stack collision\n", 25);
+#define MESSAGE "Heap and stack collision\n"
+      _write (1, MESSAGE, sizeof MESSAGE);
       abort ();
     }
+
   heap_end += incr;
+
   return (caddr_t) prev_heap_end;
 }

PPS. Assuming that you approve the newlib/libgloss patch, I will apply
this patch to the linker sources:
 
Index: ld/scripttempl/v850.sc
===================================================================
RCS file: /cvs/src/src/ld/scripttempl/v850.sc,v
retrieving revision 1.10
diff -u -3 -p -r1.10 v850.sc
--- ld/scripttempl/v850.sc	10 Feb 2011 08:18:58 -0000	1.10
+++ ld/scripttempl/v850.sc	23 May 2011 09:38:00 -0000
@@ -180,6 +180,7 @@ SECTIONS
 
   ${RELOCATING+_end = . ;}
   ${RELOCATING+PROVIDE (end = .);}
+  ${RELOCATING+PROVIDE (_heap_start = .);}
 
   /* Stabs debugging sections.  */
   .stab 0		: { *(.stab) }