New patch to review for coreboot: 647507e load_payload: Use 32-bit accesses to speed up decompression.

[Vladimir Serbinenko]

Vladimir Serbinenko ([e-mail]) just uploaded a new patch set to gerrit, which you can find at http://review.coreboot.org/5144

-gerrit

commit 647507ee168359b3bfad0370e5536f355ce25fae
Author: Vladimir Serbinenko 
Date:   Wed Feb 5 17:00:40 2014 +0100

load_payload: Use 32-bit accesses to speed up decompression.

Flash prefers 32-bit sequential access. On some platforms ROM is
    not cached due to i.a. MTRR shortage. Moreover ROM caching is not currently
    enabled by default. With this patch payload decompress is sped up by factor of
    4.

Change-Id: Id17e61316dbbf73f4a837bf173f88bf26c01c62b
    Signed-off-by: Vladimir Serbinenko 
---
 src/lib/cbfs_core.c  |  6 ++++++
 src/lib/lzmadecode.c | 11 ++++++++++-
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/src/lib/cbfs_core.c b/src/lib/cbfs_core.c
index 839b994..50c037e 100644
--- a/src/lib/cbfs_core.c
+++ b/src/lib/cbfs_core.c
@@ -202,6 +202,12 @@ int cbfs_decompress(int algo, void *src, void *dst, int len)
 {
    switch (algo) {
    	case CBFS_COMPRESS_NONE:
+			/* Reads need to be aligned at 4 bytes to avoid
+			   poor flash performance.  */
+			while (len && ((u32)src & 3)) {
+				*(u8*)dst++ = *(u8*)src++;
+				len--;
+			}
    		memmove(dst, src, len);
    		return len;
 #ifdef CBFS_CORE_WITH_LZMA
diff --git a/src/lib/lzmadecode.c b/src/lib/lzmadecode.c
index 1cf647d..b27e811 100644
--- a/src/lib/lzmadecode.c
+++ b/src/lib/lzmadecode.c
@@ -28,7 +28,10 @@
 #define kBitModelTotal (1 << kNumBitModelTotalBits)
 #define kNumMoveBits 5

-#define RC_READ_BYTE (*Buffer++)
+/* Use 32-bit reads whenever possible to avoid bad flash performance.  */
+#define RC_READ_BYTE (look_ahead_ptr < 4 ? look_ahead.raw[look_ahead_ptr++] \
+		      : ((((UInt32) Buffer & 3) || ((unsigned long long) (BufferLim - Buffer) < 4)) ? (*Buffer++) \
+	   : ((look_ahead.dw = *(UInt32 *)Buffer), (Buffer += 4), (look_ahead_ptr = 1), look_ahead.raw[0])))

#define RC_INIT2 Code = 0; Range = 0xFFFFFFFF; \
   { int i; for(i = 0; i < 5; i++) { RC_TEST; Code = (Code << 8) | RC_READ_BYTE; }}
@@ -149,6 +152,12 @@ int LzmaDecode(CLzmaDecoderState *vs,
   int len = 0;
   const Byte *Buffer;
   const Byte *BufferLim;
+  int look_ahead_ptr = 4;
+  union
+  {
+	  Byte raw[4];
+	  UInt32 dw;
+  } look_ahead;
   UInt32 Range;
   UInt32 Code;