[PATCH] sbc: ensure 16-byte buffer position alignment for 4 subbands encoding

[PATCH] sbc: ensure 16-byte buffer position alignment for 4 subbands encoding

[Siarhei Siamashka]

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Hello,

Buffer position in X array was not always 16-bytes aligned. Strict 16-byte 
alignment is strictly required for powerpc altivec simd optimizations because
altivec does not have support for unaligned vector loads at all.

-- 
Best regards,
Siarhei Siamashka

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From b8570469477f1a92089cd12bcf6c07247ca110d4 Mon Sep 17 00:00:00 2001
From: Siarhei Siamashka <siarhei.siamashka@nokia.com>
Date: Mon, 16 Mar 2009 02:27:26 +0200
Subject: [PATCH] sbc: ensure 16-byte buffer position alignment for 4 subbands encoding

Buffer position in X array was not always 16-bytes aligned.
Strict 16-byte alignment is strictly required for powerpc altivec
simd optimizations because altivec does not have support for
unaligned vector loads at all.
---
 sbc/sbc.c            |    2 +-
 sbc/sbc_primitives.c |    6 +++---
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/sbc/sbc.c b/sbc/sbc.c
index a33ed57..f40def8 100644
--- a/sbc/sbc.c
+++ b/sbc/sbc.c
@@ -924,7 +924,7 @@ static void sbc_encoder_init(struct sbc_encoder_state *state,
 				const struct sbc_frame *frame)
 {
 	memset(&state->X, 0, sizeof(state->X));
-	state->position = SBC_X_BUFFER_SIZE - frame->subbands * 9;
+	state->position = (SBC_X_BUFFER_SIZE - frame->subbands * 9) & ~7;
 
 	sbc_init_primitives(state);
 }
diff --git a/sbc/sbc_primitives.c b/sbc/sbc_primitives.c
index 6b0be3f..2105280 100644
--- a/sbc/sbc_primitives.c
+++ b/sbc/sbc_primitives.c
@@ -231,12 +231,12 @@ static SBC_ALWAYS_INLINE int sbc_encoder_process_input_s4_internal(
 	/* handle X buffer wraparound */
 	if (position < nsamples) {
 		if (nchannels > 0)
-			memcpy(&X[0][SBC_X_BUFFER_SIZE - 36], &X[0][position],
+			memcpy(&X[0][SBC_X_BUFFER_SIZE - 40], &X[0][position],
 							36 * sizeof(int16_t));
 		if (nchannels > 1)
-			memcpy(&X[1][SBC_X_BUFFER_SIZE - 36], &X[1][position],
+			memcpy(&X[1][SBC_X_BUFFER_SIZE - 40], &X[1][position],
 							36 * sizeof(int16_t));
-		position = SBC_X_BUFFER_SIZE - 36;
+		position = SBC_X_BUFFER_SIZE - 40;
 	}
 
 	#define PCM(i) (big_endian ? \
-- 
1.5.6.5

Re: [PATCH] sbc: ensure 16-byte buffer position alignment for 4 subbands encoding

[Marcel Holtmann]

Hi Siarhei,

> Buffer position in X array was not always 16-bytes aligned. Strict 16-byte 
> alignment is strictly required for powerpc altivec simd optimizations because
> altivec does not have support for unaligned vector loads at all.

patch has been applied. Thanks.

Regards

Marcel