amp filter improvements.

[paraslash.git] / amp_filter.c

diff --git a/amp_filter.c b/amp_filter.c
index 0ed2d8e0f13e5391698901fc9dd6e5af1af3463d..c0835f806ad322480cb38e7ca851b1ef78b3e366 100644 (file)
--- a/amp_filter.c
+++ b/amp_filter.c
@@ -90,6 +90,7 @@ static void amp_open(struct filter_node *fn)
 
        pad->conf = fn->conf;
        fn->private_data = pad;
+       fn->min_iqs = 2;
        if (!pad->conf->amp_given && stat_item_values[SI_AMPLIFICATION])
                sscanf(stat_item_values[SI_AMPLIFICATION], "%u", &pad->amp);
        else
@@ -104,47 +105,52 @@ static void amp_post_select(__a_unused struct sched *s, struct task *t)
        struct private_amp_data *pad = fn->private_data;
        struct btr_node *btrn = fn->btrn;
        int ret, factor = 64 + pad->amp;
-       char *in;
-       size_t in_len = btr_next_buffer(btrn, &in);
-       size_t i, length = in_len / 2;
-       int16_t *ip = (int16_t *)in, *op;
+       size_t i, in_bytes, len;
+       int16_t *in, *out;
        bool inplace = btr_inplace_ok(btrn);
 
+       if (pad->amp == 0) { /* no amplification */
+               t->error = -E_AMP_ZERO_AMP;
+               btr_splice_out_node(btrn);
+               amp_close(fn);
+               return;
+       }
+next_buffer:
        ret = prepare_filter_node(fn);
+       in_bytes = btr_next_buffer(btrn, (char **)&in);
        if (ret < 0)
                goto err;
-       if (ret == 0)
+       len = in_bytes / 2;
+       /* len == 0 happens if eof and in_bytes == 1. */
+       if (ret == 0 || len == 0)
                return;
 
        if (inplace)
-               op = ip;
+               out = in;
        else
-               op = para_malloc(length * 2);
-       if (pad->amp == 0) {
-               memcpy(op, ip, length * 2);
-               goto success;
-       }
-       for (i = 0; i < length; i++) {
-               int x = (ip[i] * factor) >> 6;
+               out = para_malloc(len * 2);
 
-               op[i] = x;
-               if (op[i] != x)
-                       op[i] = (x >= 32768)? 32767 : -32768;
+       for (i = 0; i < len; i++) {
+               int x = (in[i] * factor) >> 6;
+
+               out[i] = x;
+               if (out[i] != x) /* overflow, clip */
+                       out[i] = (x >= 0)? 32767 : -32768;
        }
-success:
-       t->error = 0;
+
        if (inplace)
                btr_pushdown_one(btrn);
        else {
-               btr_consume(btrn, length * 2);
-               btr_add_output((char *)op, length * 2, btrn);
+               btr_consume(btrn, len * 2);
+               btr_add_output((char *)out, len * 2, btrn);
        }
-       return;
+       t->error = 0;
+       goto next_buffer;
 err:
        assert(ret < 0);
-       amp_close(fn);
        t->error = ret;
        btr_del_node(btrn);
+       amp_close(fn);
 }
 
 /**