[PATCH] regcache raw read/write partial; Was: [PATCH] Remove somewrite_register_bytes occurences from i386-tdep.c

[Andrew Cagney <ac131313 at ges dot redhat dot com>]

>    Date: Sun, 18 Aug 2002 16:08:06 -0400
>    From: Andrew Cagney <ac131313@ges.redhat.com>
>
>    > As for write_register_bytes() can it be avoided?  I've just posted ``regcache_cooked_write_with_offset_hack().  But I don't think that hack is right here.  Perhaphs a single register read - modify - write function is needed?
>
>    Hmm,
>
>    I just hit a need for the same operation while implementing some pseudo 
>    registers.  Just adding:
>
>    regcache_raw_read_part(regcache,regnum,offset,length,buf)
>    regcache_raw_write_part(regcache,regnum,offset,length,buf)
>
> Where OFFSET would be the byte offset into the register I suppose.
>
> Seems like a good idea to me.
Yes, something like the attached.

I'll commit in a few hours,
Andrew

2002-08-18  Andrew Cagney  <ac131313@redhat.com>

	* regcache.c (regcache_raw_xfer_part): New function.

	* regcache.h (regcache_raw_read_part): Declare.
	(regcache_raw_write_part): Declare.
	

Index: regcache.c
===================================================================
RCS file: /cvs/src/src/gdb/regcache.c,v
retrieving revision 1.53
diff -u -r1.53 regcache.c
--- regcache.c	13 Aug 2002 23:06:40 -0000	1.53
+++ regcache.c	18 Aug 2002 20:27:18 -0000
@@ -916,6 +916,46 @@
     }
 }
 
+/* Perform a partial register transfer using a read, modify, write
+   operation.  */
+
+void
+regcache_raw_xfer_part (struct regcache *regcache, int regnum,
+			int offset, int len, void *in, const void *out)
+{
+  struct regcache_descr *descr = regcache->descr;
+  bfd_byte *reg = alloca (descr->max_register_size);
+  gdb_assert (regnum >= 0 && regnum < descr->nr_raw_registers);
+  gdb_assert (offset >= 0 && offset < descr->sizeof_register[regnum]);
+  gdb_assert (len >= 0 && len + offset < descr->sizeof_register[regnum]);
+  /* Read (when needed) ... */
+  if (in != NULL
+      || offset > 0
+      || offset + len < descr->sizeof_register[regnum])
+    regcache_raw_read (regcache, regnum, reg);
+  /* ... modify ... */
+  if (in != NULL)
+    memcpy (in, reg + offset, len);
+  if (out != NULL)
+    memcpy (reg + offset, out, len);
+  /* ... write (when needed).  */
+  if (out != NULL)
+    regcache_raw_write (regcache, regnum, reg);
+}
+
+void
+regcache_raw_read_part (struct regcache *regcache, int regnum,
+			int offset, int len, void *buf)
+{
+  regcache_raw_xfer_part (regcache, regnum, offset, len, buf, NULL);
+}
+
+void
+regcache_raw_write_part (struct regcache *regcache, int regnum,
+			 int offset, int len, const void *buf)
+{
+  regcache_raw_xfer_part (regcache, regnum, offset, len, NULL, buf);
+}
 
 /* Return the contents of register REGNUM as an unsigned integer.  */
 
Index: regcache.h
===================================================================
RCS file: /cvs/src/src/gdb/regcache.h,v
retrieving revision 1.14
diff -u -r1.14 regcache.h
--- regcache.h	13 Aug 2002 14:32:28 -0000	1.14
+++ regcache.h	18 Aug 2002 20:27:18 -0000
@@ -44,6 +44,13 @@
 					int regnum, ULONGEST *val);
 int regcache_valid_p (struct regcache *regcache, int regnum);
 
+/* Raw partial transfers.  These perform read, modify, write style
+   operations.  */
+void regcache_raw_read_part (struct regcache *regcache, int regnum,
+			     int offset, int len, void *buf);
+void regcache_raw_write_part (struct regcache *regcache, int regnum,
+			      int offset, int len, const void *buf);
+
 /* Transfer a cooked register [0..NUM_REGS+NUM_PSEUDO_REGS).  */
 void regcache_cooked_read (struct regcache *regcache, int rawnum, void *buf);
 void regcache_cooked_write (struct regcache *regcache, int rawnum,