Add some CACHEALIGN_* macros and a helper function to assist in aligning data and buffers on PortalPlayer processors to cache line boundaries. They're noops when PROC_NEED_CACHEALIGN isn't defined. Go safe and increase the value to 32 since I'm not sure yet if 16 is sufficient - changing that is a one-liner. Add helper to plugin API which will be needed shortly.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@15523 a1c6a512-1295-4272-9138-f99709370657

2 files changed, 34 insertions, 0 deletions

diff --git a/firmware/export/general.h b/firmware/export/general.h
index 427e2773b8..f4ea9e206a 100644
--- a/firmware/export/general.h
+++ b/firmware/export/general.h
@@ -21,6 +21,7 @@
 #define GENERAL_H
 
 #include <stdbool.h>
+#include <stddef.h>
 
 /* round a signed/unsigned 32bit value to the closest of a list of values */
 /* returns the index of the closest value */
@@ -34,5 +35,6 @@ int make_list_from_caps32(unsigned long src_mask,
                           unsigned long caps_mask,
                           unsigned long *caps_list);
 
+size_t align_buffer(void **start, size_t size, size_t align);
 
 #endif /* GENERAL_H */
diff --git a/firmware/export/system.h b/firmware/export/system.h
index dc10c4545f..cba4b81631 100644
--- a/firmware/export/system.h
+++ b/firmware/export/system.h
@@ -229,4 +229,36 @@ static inline uint32_t swap_odd_even32(uint32_t value)
 #define flush_icache()
 #endif
 
+#ifdef PROC_NEEDS_CACHEALIGN
+/* Cache alignment attributes and sizes are enabled */
+
+/* 2^CACHEALIGN_BITS = the byte size */
+#define CACHEALIGN_SIZE (1u << CACHEALIGN_BITS)
+
+#define CACHEALIGN_ATTR __attribute__((aligned(CACHEALIGN_SIZE)))
+/* Aligns x up to a CACHEALIGN_SIZE boundary */
+#define CACHEALIGN_UP(x) \
+    ((typeof (x))ALIGN_UP_P2((uintptr_t)(x), CACHEALIGN_BITS))
+/* Aligns x down to a CACHEALIGN_SIZE boundary */
+#define CACHEALIGN_DOWN(x) \
+    ((typeof (x))ALIGN_DOWN_P2((uintptr_t)(x), CACHEALIGN_BITS))
+/* Aligns at least to the greater of size x or CACHEALIGN_SIZE */
+#define CACHEALIGN_AT_LEAST_ATTR(x) __attribute__((aligned(CACHEALIGN_UP(x))))
+/* Aligns a buffer pointer and size to proper boundaries */
+#define CACHEALIGN_BUFFER(start, size) \
+    ({ align_buffer((start), (size), CACHEALIGN_SIZE); })
+
+#else /* ndef PROC_NEEDS_CACHEALIGN */
+
+/* Cache alignment attributes and sizes are not enabled */
+#define CACHEALIGN_ATTR
+#define CACHEALIGN_AT_LEAST_ATTR(x) __attribute__((aligned(x)))
+#define CACHEALIGN_UP(x) (x)
+#define CACHEALIGN_DOWN(x) (x)
+/* Make no adjustments */
+#define CACHEALIGN_BUFFER(start, size) \
+    ({ (void)(start); (size); })
+
+#endif /* PROC_NEEDS_CACHEALIGN */
+
 #endif /* __SYSTEM_H__ */