Preparation for more rate conversion types

diff --git a/src/pcm/pcm_rate.c b/src/pcm/pcm_rate.c
index 0fefae4e8881b7185bcea11b434cba7959d52d8f..cae92e8f51becc8997bab0933db7d6350f8e8ad3 100644 (file)
--- a/src/pcm/pcm_rate.c
+++ b/src/pcm/pcm_rate.c
@@ -40,11 +40,21 @@ const char *_snd_module_pcm_rate = "";
 
 #define DIV (1<<16)
 
+enum rate_type {
+       RATE_TYPE_LINEAR,               /* linear interpolation */
+       RATE_TYPE_BANDLIMIT,            /* bandlimited interpolation */
+       RATE_TYPE_POLYPHASE,            /* polyphase resampling */
+};
+
 typedef struct {
-       int init;
-       int16_t old_sample, new_sample;
-       int sum;
-       unsigned int pos;
+       union {
+               struct {
+                       int init;
+                       int16_t old_sample, new_sample;
+                       int sum;
+                       unsigned int pos;
+               } linear;
+       } u;
 } snd_pcm_rate_state_t;
  
 typedef snd_pcm_uframes_t (*rate_f)(const snd_pcm_channel_area_t *dst_areas,
@@ -61,6 +71,7 @@ typedef snd_pcm_uframes_t (*rate_f)(const snd_pcm_channel_area_t *dst_areas,
 typedef struct {
        /* This field need to be the first */
        snd_pcm_plugin_t plug;
+       enum rate_type type;
        unsigned int get_idx;
        unsigned int put_idx;
        unsigned int pitch;
@@ -117,24 +128,24 @@ static snd_pcm_uframes_t snd_pcm_rate_expand(const snd_pcm_channel_area_t *dst_a
                const char *src;
                char *dst;
                int src_step, dst_step;
-               int16_t old_sample = states->old_sample;
-               int16_t new_sample = states->new_sample;
-               unsigned int pos = states->pos;
+               int16_t old_sample = states->u.linear.old_sample;
+               int16_t new_sample = states->u.linear.new_sample;
+               unsigned int pos = states->u.linear.pos;
                src = snd_pcm_channel_area_addr(src_area, src_offset);
                dst = snd_pcm_channel_area_addr(dst_area, dst_offset);
                src_step = snd_pcm_channel_area_step(src_area);
                dst_step = snd_pcm_channel_area_step(dst_area);
                src_frames1 = 0;
                dst_frames1 = 0;
-               if (! states->init) {
+               if (! states->u.linear.init) {
                        sample = initial_sample(src, getidx);
                        old_sample = new_sample = sample;
                        src += src_step;
                        src_frames1++;
-                       states->init = 2; /* get a new sample */
+                       states->u.linear.init = 2; /* get a new sample */
                }
                while (dst_frames1 < dst_frames) {
-                       if (states->init == 2) {
+                       if (states->u.linear.init == 2) {
                                old_sample = new_sample;
                                goto *get;
 #define GET16_END after_get
@@ -142,7 +153,7 @@ static snd_pcm_uframes_t snd_pcm_rate_expand(const snd_pcm_channel_area_t *dst_a
 #undef GET16_END
                        after_get:
                                new_sample = sample;
-                               states->init = 1;
+                               states->u.linear.init = 1;
                        }
                        sample = (((int64_t)old_sample * (int64_t)(get_threshold - pos)) + ((int64_t)new_sample * pos)) / get_threshold;
                        goto *put;
@@ -157,14 +168,14 @@ static snd_pcm_uframes_t snd_pcm_rate_expand(const snd_pcm_channel_area_t *dst_a
                                pos -= get_threshold;
                                src += src_step;
                                src_frames1++;
-                               states->init = 2; /* get a new sample */
+                               states->u.linear.init = 2; /* get a new sample */
                                if (src_frames1 >= src_frames)
                                        break;
                        }
                } 
-               states->old_sample = old_sample;
-               states->new_sample = new_sample;
-               states->pos = pos;
+               states->u.linear.old_sample = old_sample;
+               states->u.linear.new_sample = new_sample;
+               states->u.linear.pos = pos;
                states++;
        }
        *dst_framesp = dst_frames1;
@@ -204,9 +215,9 @@ static snd_pcm_uframes_t snd_pcm_rate_shrink(const snd_pcm_channel_area_t *dst_a
                const char *src;
                char *dst;
                int src_step, dst_step;
-               sum = states->sum;
-               pos = states->pos;
-               states->init = 0;
+               sum = states->u.linear.sum;
+               pos = states->u.linear.pos;
+               states->u.linear.init = 0;
                src = snd_pcm_channel_area_addr(src_area, src_offset);
                dst = snd_pcm_channel_area_addr(dst_area, dst_offset);
                src_step = snd_pcm_channel_area_step(src_area);
@@ -242,8 +253,8 @@ static snd_pcm_uframes_t snd_pcm_rate_shrink(const snd_pcm_channel_area_t *dst_a
                        } else
                                sum += sample * get_increment;
                }
-               states->sum = sum;
-               states->pos = pos;
+               states->u.linear.sum = sum;
+               states->u.linear.pos = pos;
                states++;
        }
        *dst_framesp = dst_frames1;
@@ -488,12 +499,17 @@ static int snd_pcm_rate_init(snd_pcm_t *pcm)
 {
        snd_pcm_rate_t *rate = pcm->private_data;
        unsigned int k;
-       for (k = 0; k < pcm->channels; ++k) {
-               rate->states[k].sum = 0;
-               rate->states[k].old_sample = 0;
-               rate->states[k].new_sample = 0;
-               rate->states[k].pos = 0;
-               rate->states[k].init = 0;
+       switch (rate->type) {
+       case RATE_TYPE_LINEAR:
+               for (k = 0; k < pcm->channels; ++k) {
+                       rate->states[k].u.linear.sum = 0;
+                       rate->states[k].u.linear.old_sample = 0;
+                       rate->states[k].u.linear.new_sample = 0;
+                       rate->states[k].u.linear.pos = 0;
+                       rate->states[k].u.linear.init = 0;
+               }
+       default:
+               assert(0);
        }
        return 0;
 }
@@ -617,6 +633,7 @@ int snd_pcm_rate_open(snd_pcm_t **pcmp, const char *name, snd_pcm_format_t sform
                return -ENOMEM;
        }
        snd_pcm_plugin_init(&rate->plug);
+       rate->type = RATE_TYPE_LINEAR;
        rate->srate = srate;
        rate->sformat = sformat;
        rate->plug.read = snd_pcm_rate_read_areas;