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SubjectRe: [PATCH 1/2] lib: Add lz4 compressor module
From
On Thu, Mar 14, 2013 at 10:48 AM, Chanho Min <chanho.min@lge.com> wrote:
> +#ifdef __BIG_ENDIAN
> +#define LZ4_NBCOMMONBYTES(val) (__builtin_clzll(val) >> 3)
> +#else
> +#define LZ4_NBCOMMONBYTES(val) (__builtin_ctzll(val) >> 3)
> +#endif
>
> #else /* 32-bit */
> #define STEPSIZE 4
> @@ -83,6 +130,14 @@ typedef struct _U64_S { u64 v; } U64_S;
> } while (0)
>
> #define LZ4_SECURECOPY LZ4_WILDCOPY
> +#define HTYPE const u8*
> +
> +#ifdef __BIG_ENDIAN
> +#define LZ4_NBCOMMONBYTES(val) (__builtin_clz(val) >> 3)
> +#else
> +#define LZ4_NBCOMMONBYTES(val) (__builtin_ctz(val) >> 3)
> +#endif

It seems at least m68k and sparc don't have the __builtin_clz() functions:

m68k-allmodconfig (http://kisskb.ellerman.id.au/kisskb/buildresult/8572593/):

ERROR: "__clzsi2" [lib/lz4/lz4hc_compress.ko] undefined!
ERROR: "__clzsi2" [lib/lz4/lz4_compress.ko] undefined!

sparc64-allmodconfig (http://kisskb.ellerman.id.au/kisskb/buildresult/8572790/):

ERROR: "__clzdi2" [lib/lz4/lz4hc_compress.ko] undefined!
ERROR: "__clzdi2" [lib/lz4/lz4_compress.ko] undefined!

sparc-allmodconfig (http://kisskb.ellerman.id.au/kisskb/buildresult/8572795/):

ERROR: "__clzdi2" [lib/lz4/lz4hc_compress.ko] undefined!
ERROR: "__clzdi2" [lib/lz4/lz4_compress.ko] undefined!

There may be more, hidden by build errors before reaching the link or modpost
phases.

The gmail-whitespace-damaged patch below fixes the m68k and sparc builds
for me, does this look acceptable?

diff --git a/lib/lz4/lz4defs.h b/lib/lz4/lz4defs.h
index abcecdc..81d3251 100644
--- a/lib/lz4/lz4defs.h
+++ b/lib/lz4/lz4defs.h
@@ -107,12 +107,6 @@ typedef struct _U64_S { u64 v; } U64_S;
} while (0)
#define HTYPE u32

-#ifdef __BIG_ENDIAN
-#define LZ4_NBCOMMONBYTES(val) (__builtin_clzll(val) >> 3)
-#else
-#define LZ4_NBCOMMONBYTES(val) (__builtin_ctzll(val) >> 3)
-#endif
-
#else /* 32-bit */
#define STEPSIZE 4

@@ -132,12 +126,12 @@ typedef struct _U64_S { u64 v; } U64_S;
#define LZ4_SECURECOPY LZ4_WILDCOPY
#define HTYPE const u8*

-#ifdef __BIG_ENDIAN
-#define LZ4_NBCOMMONBYTES(val) (__builtin_clz(val) >> 3)
-#else
-#define LZ4_NBCOMMONBYTES(val) (__builtin_ctz(val) >> 3)
#endif

+#ifdef __BIG_ENDIAN
+#define LZ4_NBCOMMONBYTES(val) (((STEPSIZE * 8) - 1 - __fls(val)) >> 3)
+#else
+#define LZ4_NBCOMMONBYTES(val) (__ffs(val) >> 3)
#endif

#define LZ4_READ_LITTLEENDIAN_16(d, s, p) \
Gr{oetje,eeting}s,
Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds


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