[PATCH v4 02/16] sbc: Break 4 blocks processing to variable steps

["Frédéric Dalleau" <frederic.dalleau@linux.intel.com>]

Until now SBC processed 4 blocks at a time. If we want to process 15 blocks,
then we need to break this processing in one block steps. 4 blocks is still
default increment.
---
 sbc/sbc.c            |   19 +++++++++++--------
 sbc/sbc_primitives.h |    6 ++++--
 2 files changed, 15 insertions(+), 10 deletions(-)

diff --git a/sbc/sbc.c b/sbc/sbc.c
index e51ed57..4a7dd2e 100644
--- a/sbc/sbc.c
+++ b/sbc/sbc.c
@@ -688,30 +688,32 @@ static int sbc_analyze_audio(struct sbc_encoder_state *state,
 	switch (frame->subbands) {
 	case 4:
 		for (ch = 0; ch < frame->channels; ch++) {
-			x = &state->X[ch][state->position - 16 +
-							frame->blocks * 4];
-			for (blk = 0; blk < frame->blocks; blk += 4) {
+			x = &state->X[ch][state->position - 4 *
+					state->increment + frame->blocks * 4];
+			for (blk = 0; blk < frame->blocks;
+						blk += state->increment) {
 				state->sbc_analyze_4b_4s(
 					state, x,
 					frame->sb_sample_f[blk][ch],
 					frame->sb_sample_f[blk + 1][ch] -
 					frame->sb_sample_f[blk][ch]);
-				x -= 16;
+				x -= 4 * state->increment;
 			}
 		}
 		return frame->blocks * 4;
 
 	case 8:
 		for (ch = 0; ch < frame->channels; ch++) {
-			x = &state->X[ch][state->position - 32 +
-							frame->blocks * 8];
-			for (blk = 0; blk < frame->blocks; blk += 4) {
+			x = &state->X[ch][state->position - 8 *
+					state->increment + frame->blocks * 8];
+			for (blk = 0; blk < frame->blocks;
+						blk += state->increment) {
 				state->sbc_analyze_4b_8s(
 					state, x,
 					frame->sb_sample_f[blk][ch],
 					frame->sb_sample_f[blk + 1][ch] -
 					frame->sb_sample_f[blk][ch]);
-				x -= 32;
+				x -= 8 * state->increment;
 			}
 		}
 		return frame->blocks * 8;
@@ -906,6 +908,7 @@ static void sbc_encoder_init(struct sbc_encoder_state *state,
 {
 	memset(&state->X, 0, sizeof(state->X));
 	state->position = (SBC_X_BUFFER_SIZE - frame->subbands * 9) & ~7;
+	state->increment = 4;
 
 	sbc_init_primitives(state);
 }
diff --git a/sbc/sbc_primitives.h b/sbc/sbc_primitives.h
index a7bbef1..2a7d4a1 100644
--- a/sbc/sbc_primitives.h
+++ b/sbc/sbc_primitives.h
@@ -38,13 +38,15 @@
 
 struct sbc_encoder_state {
 	int position;
+	/* Number of consecutive blocks handled by the encoder */
+	int increment;
 	int16_t SBC_ALIGNED X[2][SBC_X_BUFFER_SIZE];
 	/* Polyphase analysis filter for 4 subbands configuration,
-	 * it handles 4 blocks at once */
+	 * it handles "increment" blocks at once */
 	void (*sbc_analyze_4b_4s)(struct sbc_encoder_state *state,
 			int16_t *x, int32_t *out, int out_stride);
 	/* Polyphase analysis filter for 8 subbands configuration,
-	 * it handles 4 blocks at once */
+	 * it handles "increment" blocks at once */
 	void (*sbc_analyze_4b_8s)(struct sbc_encoder_state *state,
 			int16_t *x, int32_t *out, int out_stride);
 	/* Process input data (deinterleave, endian conversion, reordering),
-- 
1.7.9.5