target: Rewrite read/write buffer default implementations

Rewrite the target_*_buffer_default to generate as large accesses as
possible while maintaining natural alignment.

These versions are easy to extend to generate 8-byte accesses to support
64-bit targets, although it requires some conformity from all target
implementations (i.e. they need to refuse unsupported access sizes with
some defined error code, so we can try again with a smaller one).

Change-Id: I00ddcbb1d2fd33f9f8b99cb448cc93505a2421fc
Signed-off-by: Andreas Fritiofson <andreas.fritiofson@gmail.com>
Reviewed-on: http://openocd.zylin.com/1221
Tested-by: jenkins
Reviewed-by: Spencer Oliver <spen@spen-soft.co.uk>

diff --git a/src/target/target.c b/src/target/target.c
index 6aee09832e3983362d278c3caef9394c66cf7fed..d34e14418ff608b2dfe805edcc136b6cf6a684f2 100644 (file)
--- a/src/target/target.c
+++ b/src/target/target.c
@@ -60,9 +60,9 @@
 #define DEFAULT_HALT_TIMEOUT 5000
 
 static int target_read_buffer_default(struct target *target, uint32_t address,
-               uint32_t size, uint8_t *buffer);
+               uint32_t count, uint8_t *buffer);
 static int target_write_buffer_default(struct target *target, uint32_t address,
-               uint32_t size, const uint8_t *buffer);
+               uint32_t count, const uint8_t *buffer);
 static int target_array2mem(Jim_Interp *interp, struct target *target,
                int argc, Jim_Obj * const *argv);
 static int target_mem2array(Jim_Interp *interp, struct target *target,
@@ -1766,50 +1766,37 @@ int target_write_buffer(struct target *target, uint32_t address, uint32_t size,
        return target->type->write_buffer(target, address, size, buffer);
 }
 
-static int target_write_buffer_default(struct target *target, uint32_t address, uint32_t size, const uint8_t *buffer)
+static int target_write_buffer_default(struct target *target, uint32_t address, uint32_t count, const uint8_t *buffer)
 {
-       int retval = ERROR_OK;
-
-       if (((address % 2) == 0) && (size == 2))
-               return target_write_memory(target, address, 2, 1, buffer);
-
-       /* handle unaligned head bytes */
-       if (address % 4) {
-               uint32_t unaligned = 4 - (address % 4);
-
-               if (unaligned > size)
-                       unaligned = size;
-
-               retval = target_write_memory(target, address, 1, unaligned, buffer);
-               if (retval != ERROR_OK)
-                       return retval;
-
-               buffer += unaligned;
-               address += unaligned;
-               size -= unaligned;
-       }
-
-       /* handle aligned words */
-       if (size >= 4) {
-               int aligned = size - (size % 4);
-
-               retval = target_write_memory(target, address, 4, aligned / 4, buffer);
-               if (retval != ERROR_OK)
-                       return retval;
+       uint32_t size;
 
-               buffer += aligned;
-               address += aligned;
-               size -= aligned;
+       /* Align up to maximum 4 bytes. The loop condition makes sure the next pass
+        * will have something to do with the size we leave to it. */
+       for (size = 1; size < 4 && count >= size * 2 + (address & size); size *= 2) {
+               if (address & size) {
+                       int retval = target_write_memory(target, address, size, 1, buffer);
+                       if (retval != ERROR_OK)
+                               return retval;
+                       address += size;
+                       count -= size;
+                       buffer += size;
+               }
        }
 
-       /* handle tail writes of less than 4 bytes */
-       if (size > 0) {
-               retval = target_write_memory(target, address, 1, size, buffer);
-               if (retval != ERROR_OK)
-                       return retval;
+       /* Write the data with as large access size as possible. */
+       for (; size > 0; size /= 2) {
+               uint32_t aligned = count - count % size;
+               if (aligned > 0) {
+                       int retval = target_write_memory(target, address, size, aligned / size, buffer);
+                       if (retval != ERROR_OK)
+                               return retval;
+                       address += aligned;
+                       count -= aligned;
+                       buffer += aligned;
+               }
        }
 
-       return retval;
+       return ERROR_OK;
 }
 
 /* Single aligned words are guaranteed to use 16 or 32 bit access
@@ -1840,58 +1827,34 @@ int target_read_buffer(struct target *target, uint32_t address, uint32_t size, u
        return target->type->read_buffer(target, address, size, buffer);
 }
 
-static int target_read_buffer_default(struct target *target, uint32_t address, uint32_t size, uint8_t *buffer)
+static int target_read_buffer_default(struct target *target, uint32_t address, uint32_t count, uint8_t *buffer)
 {
-       int retval = ERROR_OK;
+       uint32_t size;
 
-       if (((address % 2) == 0) && (size == 2))
-               return target_read_memory(target, address, 2, 1, buffer);
-
-       /* handle unaligned head bytes */
-       if (address % 4) {
-               uint32_t unaligned = 4 - (address % 4);
-
-               if (unaligned > size)
-                       unaligned = size;
-
-               retval = target_read_memory(target, address, 1, unaligned, buffer);
-               if (retval != ERROR_OK)
-                       return retval;
-
-               buffer += unaligned;
-               address += unaligned;
-               size -= unaligned;
-       }
-
-       /* handle aligned words */
-       if (size >= 4) {
-               int aligned = size - (size % 4);
-
-               retval = target_read_memory(target, address, 4, aligned / 4, buffer);
-               if (retval != ERROR_OK)
-                       return retval;
-
-               buffer += aligned;
-               address += aligned;
-               size -= aligned;
+       /* Align up to maximum 4 bytes. The loop condition makes sure the next pass
+        * will have something to do with the size we leave to it. */
+       for (size = 1; size < 4 && count >= size * 2 + (address & size); size *= 2) {
+               if (address & size) {
+                       int retval = target_read_memory(target, address, size, 1, buffer);
+                       if (retval != ERROR_OK)
+                               return retval;
+                       address += size;
+                       count -= size;
+                       buffer += size;
+               }
        }
 
-       /*prevent byte access when possible (avoid AHB access limitations in some cases)*/
-       if (size        >= 2) {
-               int aligned = size - (size % 2);
-               retval = target_read_memory(target, address, 2, aligned / 2, buffer);
-               if (retval != ERROR_OK)
-                       return retval;
-
-               buffer += aligned;
-               address += aligned;
-               size -= aligned;
-       }
-       /* handle tail writes of less than 4 bytes */
-       if (size > 0) {
-               retval = target_read_memory(target, address, 1, size, buffer);
-               if (retval != ERROR_OK)
-                       return retval;
+       /* Read the data with as large access size as possible. */
+       for (; size > 0; size /= 2) {
+               uint32_t aligned = count - count % size;
+               if (aligned > 0) {
+                       int retval = target_read_memory(target, address, size, aligned / size, buffer);
+                       if (retval != ERROR_OK)
+                               return retval;
+                       address += aligned;
+                       count -= aligned;
+                       buffer += aligned;
+               }
        }
 
        return ERROR_OK;