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Subject[PATCH 2/2] zstd: use U16 data type for rankPos
Date
rankPos structure variables value can not be more than 512.
So it can easily be declared as U16 rather than U32.

It will reduce stack usage of HUF_sort from 256 bytes to 128 bytes

original:
e92ddbf0 push {r4, r5, r6, r7, r8, r9, fp, ip, lr, pc}
e24cb004 sub fp, ip, #4
e24ddc01 sub sp, sp, #256 ; 0x100

changed:
e92ddbf0 push {r4, r5, r6, r7, r8, r9, fp, ip, lr, pc}
e24cb004 sub fp, ip, #4
e24dd080 sub sp, sp, #128 ; 0x80


Signed-off-by: Maninder Singh <maninder1.s@samsung.com>
Signed-off-by: Vaneet Narang <v.narang@samsung.com>
---
lib/zstd/huf_compress.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/lib/zstd/huf_compress.c b/lib/zstd/huf_compress.c
index e727812..2203124 100644
--- a/lib/zstd/huf_compress.c
+++ b/lib/zstd/huf_compress.c
@@ -382,8 +382,8 @@ static U32 HUF_setMaxHeight(nodeElt *huffNode, U32 lastNonNull, U32 maxNbBits)
}

typedef struct {
- U32 base;
- U32 curr;
+ U16 base;
+ U16 curr;
} rankPos;

static void HUF_sort(nodeElt *huffNode, const U32 *count, U32 maxSymbolValue)
--
2.7.4
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