ALSA: pcmtest: minor optimizations

Decrease the buffer filling overhead with conditional remainder
calculation in the 'inc_buf_pos' inline function.

Fix the driver to use already defined variables where it is possible
in 'check_buf_block_ni' and 'fill_block_pattern_n' functions.
Signed-off-by: Ivan Orlov <ivan.orlov0322@gmail.com>
Link: https://lore.kernel.org/r/20230713075953.13692-2-ivan.orlov0322@gmail.comSigned-off-by: Takashi Iwai <tiwai@suse.de>

sound/drivers/pcmtest.c

@@ -144,7 +144,8 @@ static inline void inc_buf_pos(struct pcmtst_buf_iter *v_iter, size_t by, size_t
 {
 	v_iter->total_bytes += by;
 	v_iter->buf_pos += by;
-	v_iter->buf_pos %= bytes;
+	if (v_iter->buf_pos >= bytes)
+		v_iter->buf_pos %= bytes;
 }
 
 /*
@@ -200,10 +201,10 @@ static void check_buf_block_ni(struct pcmtst_buf_iter *v_iter, struct snd_pcm_ru
 	u8 current_byte;
 
 	for (i = 0; i < v_iter->b_rw; i++) {
-		current_byte = runtime->dma_area[buf_pos_n(v_iter, channels, i % channels)];
+		ch_num = i % channels;
+		current_byte = runtime->dma_area[buf_pos_n(v_iter, channels, ch_num)];
 		if (!current_byte)
 			break;
-		ch_num = i % channels;
 		if (current_byte != patt_bufs[ch_num].buf[(v_iter->total_bytes / channels)
 							  % patt_bufs[ch_num].len]) {
 			v_iter->is_buf_corrupted = true;
@@ -243,7 +244,7 @@ static void fill_block_pattern_n(struct pcmtst_buf_iter *v_iter, struct snd_pcm_
 
 	for (i = 0; i < v_iter->b_rw; i++) {
 		ch_num = i % channels;
-		runtime->dma_area[buf_pos_n(v_iter, channels, i % channels)] =
+		runtime->dma_area[buf_pos_n(v_iter, channels, ch_num)] =
 			patt_bufs[ch_num].buf[(v_iter->total_bytes / channels)
 					      % patt_bufs[ch_num].len];
 		inc_buf_pos(v_iter, 1, runtime->dma_bytes);