ALSA: firewire-lib: code refactoring for data block calculation

When calculating the number of data blocks per packet, some states are
stored in AMDTP stream structure. This is inconvenient when reuse the
calculation from non-stream structure.

This commit applies refactoring to helper function for the calculation
so that the function doesn't touch AMDTP stream structure.
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Link: https://lore.kernel.org/r/20200508043635.349339-8-o-takashi@sakamocchi.jpSigned-off-by: Takashi Iwai <tiwai@suse.de>

sound/firewire/amdtp-stream.c

@@ -339,25 +339,26 @@ void amdtp_stream_pcm_prepare(struct amdtp_stream *s)
 }
 EXPORT_SYMBOL(amdtp_stream_pcm_prepare);
 
-static unsigned int calculate_data_blocks(struct amdtp_stream *s,
-					  unsigned int syt)
+static unsigned int calculate_data_blocks(unsigned int *data_block_state,
+				bool is_blocking, bool is_no_info,
+				unsigned int syt_interval, enum cip_sfc sfc)
 {
-	unsigned int phase, data_blocks;
+	unsigned int data_blocks;
 
 	/* Blocking mode. */
-	if (s->flags & CIP_BLOCKING) {
+	if (is_blocking) {
 		/* This module generate empty packet for 'no data'. */
-		if (syt == CIP_SYT_NO_INFO)
+		if (is_no_info)
 			data_blocks = 0;
 		else
-			data_blocks = s->syt_interval;
+			data_blocks = syt_interval;
 	/* Non-blocking mode. */
 	} else {
-		if (!cip_sfc_is_base_44100(s->sfc)) {
+		if (!cip_sfc_is_base_44100(sfc)) {
 			// Sample_rate / 8000 is an integer, and precomputed.
-			data_blocks = s->ctx_data.rx.data_block_state;
+			data_blocks = *data_block_state;
 		} else {
-			phase = s->ctx_data.rx.data_block_state;
+			unsigned int phase = *data_block_state;
 
 		/*
 		 * This calculates the number of data blocks per packet so that
@@ -367,16 +368,16 @@ static unsigned int calculate_data_blocks(struct amdtp_stream *s,
 		 *    as possible in the sequence (to prevent underruns of the
 		 *    device's buffer).
 		 */
-			if (s->sfc == CIP_SFC_44100)
+			if (sfc == CIP_SFC_44100)
 				/* 6 6 5 6 5 6 5 ... */
 				data_blocks = 5 + ((phase & 1) ^
 						   (phase == 0 || phase >= 40));
 			else
 				/* 12 11 11 11 11 ... or 23 22 22 22 22 ... */
-				data_blocks = 11 * (s->sfc >> 1) + (phase == 0);
-			if (++phase >= (80 >> (s->sfc >> 1)))
+				data_blocks = 11 * (sfc >> 1) + (phase == 0);
+			if (++phase >= (80 >> (sfc >> 1)))
 				phase = 0;
-			s->ctx_data.rx.data_block_state = phase;
+			*data_block_state = phase;
 		}
 	}
 
@@ -769,7 +770,11 @@ static void generate_ideal_pkt_descs(struct amdtp_stream *s,
 		} else {
 			desc->syt = syt_offset;
 		}
-		desc->data_blocks = calculate_data_blocks(s, desc->syt);
+		desc->data_blocks =
+			calculate_data_blocks(&s->ctx_data.rx.data_block_state,
+					      !!(s->flags & CIP_BLOCKING),
+					      desc->syt == CIP_SYT_NO_INFO,
+					      s->syt_interval, s->sfc);
 
 		if (s->flags & CIP_DBC_IS_END_EVENT)
 			dbc = (dbc + desc->data_blocks) & 0xff;