[RFC 12/23] regcache: Add functions suitable for regset_supply/collect.

[Andreas Arnez <arnez@linux.vnet.ibm.com>]

These functions are intended to suit all targets that don't require too
special logic in their regset supply/collect methods.  Having such
generic functions helps reducing target-specific complexity.

gdb/
	* regcache.c: Include "regset.h".
	(regcache_supply_regset, regcache_collect_regset): New functions.
	* regcache.h (struct regcache_map_entry): New structure.
	(REGCACHE_MAP_SKIP_BYTES): New enum value.
	(regcache_supply_regset, regcache_collect_regset): New prototypes.
---
 gdb/regcache.c | 66 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 gdb/regcache.h | 38 +++++++++++++++++++++++++++++++++
 2 files changed, 104 insertions(+)

diff --git a/gdb/regcache.c b/gdb/regcache.c
index 8b588c6..b38031e 100644
--- a/gdb/regcache.c
+++ b/gdb/regcache.c
@@ -30,6 +30,7 @@
 #include "exceptions.h"
 #include "remote.h"
 #include "valprint.h"
+#include "regset.h"
 
 /*
  * DATA STRUCTURE
@@ -1031,6 +1032,71 @@ regcache_raw_collect (const struct regcache *regcache, int regnum, void *buf)
   memcpy (buf, regbuf, size);
 }
 
+/* Supply register REGNUM from BUF to REGCACHE, using the register map
+   in REGSET.  If REGNUM is -1, do this for all registers in
+   REGSET.  */
+
+void
+regcache_supply_regset (const struct regset *regset,
+			struct regcache *regcache,
+			int regnum, const void *buf, size_t size)
+{
+  const struct regcache_map_entry *map = regset->descr;
+  int offs = 0;
+  int i, count;
+
+  for (i = 0; (count = map[i].count) != 0; i++)
+    {
+      int regno = map[i].regno;
+
+      if (regno == REGCACHE_MAP_SKIP_BYTES)
+	offs += count;
+      else
+	for (; count--; regno++)
+	  {
+	    int new_offs = offs + regcache->descr->sizeof_register[regno];
+
+	    if (new_offs <= size && (regnum == -1 || regnum == regno))
+	      regcache_raw_supply (regcache, regno,
+				   buf ? (const gdb_byte *) buf + offs
+				   : NULL);
+	    offs = new_offs;
+	  }
+    }
+}
+
+/* Collect register REGNUM from REGCACHE to BUF, using the register
+   map in REGSET.  If REGNUM is -1, do this for all registers in
+   REGSET.  */
+
+void
+regcache_collect_regset (const struct regset *regset,
+			 const struct regcache *regcache,
+			 int regnum, void *buf, size_t size)
+{
+  const struct regcache_map_entry *map = regset->descr;
+  int offs = 0;
+  int i, count;
+
+  for (i = 0; (count = map[i].count) != 0; i++)
+    {
+      int regno = map[i].regno;
+
+      if (regno == REGCACHE_MAP_SKIP_BYTES)
+	offs += count;
+      else
+	for (; count--; regno++)
+	  {
+	    int new_offs = offs + regcache->descr->sizeof_register[regno];
+
+	    if (new_offs <= size && (regnum == -1 || regnum == regno))
+	      regcache_raw_collect (regcache, regno,
+				    (gdb_byte *) buf + offs);
+	    offs = new_offs;
+	  }
+    }
+}
+
 
 /* Special handling for register PC.  */
 
diff --git a/gdb/regcache.h b/gdb/regcache.h
index 8423f57..cc2bda8 100644
--- a/gdb/regcache.h
+++ b/gdb/regcache.h
@@ -147,6 +147,44 @@ extern void regcache_raw_supply (struct regcache *regcache,
 extern void regcache_raw_collect (const struct regcache *regcache,
 				  int regnum, void *buf);
 
+/* Mapping between register numbers and offsets in a buffer, for use
+   in the '*regset' functions below.  The first entry in a map refers
+   to offset 0, and each entry increases the offset by its size.
+   Specifying count=N and regno=R is equivalent to N consecutive
+   entries with count=1 and with regno ranging from R to R+N-1.  The
+   end of the map is marked with a dummy entry having count=0.  */
+
+struct regcache_map_entry
+{
+  int count;
+  int regno;
+};
+
+/* Special value for the 'regno' field in the struct above.  */
+
+enum
+  {
+    REGCACHE_MAP_SKIP_BYTES = -1,
+  };
+
+/* Transfer a set of registers (as described by REGSET) between
+   REGCACHE and BUF.  If REGNUM == -1, transfer all registers
+   belonging to the regset, otherwise just the register numbered
+   REGNUM.  The REGSET's 'descr' field must point to an array of
+   'struct regcache_map_entry'.
+
+   These functions are suitable for the 'regset_supply' and
+   'regset_collect' fields in a regset structure.
+  */
+
+extern void regcache_supply_regset (const struct regset *regset,
+				    struct regcache *regcache,
+				    int regnum, const void *buf,
+				    size_t size);
+extern void regcache_collect_regset (const struct regset *regset,
+				     const struct regcache *regcache,
+				     int regnum, void *buf, size_t size);
+
 
 /* The type of a register.  This function is slightly more efficient
    then its gdbarch vector counterpart since it returns a precomputed
-- 
1.8.4.2