codecs: Add support for the 'VTX' ZX Spectrum chiptunes format.

This codec requires floating point.

Original author:  Peter Sovietov
Ported to Rockbox:  Roman Skylarov
Further integration and bugfixes:  Solomon Peachy

Change-Id: I781ecd3592dfcdbbc694063334350342534f1d6c

1 files changed, 138 insertions, 0 deletions

diff --git a/lib/rbcodec/codecs/vtx.c b/lib/rbcodec/codecs/vtx.c
new file mode 100644
index 0000000000..031af946b9
--- /dev/null
+++ b/lib/rbcodec/codecs/vtx.c
@@ -0,0 +1,138 @@
+/***************************************************************************
+ *             __________               __   ___.
+ *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
+ *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
+ *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
+ *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
+ *                     \/            \/     \/    \/            \/
+ * $Id$
+ *
+ * VTX Codec for rockbox based on the Ayumi engine
+ *
+ * Ayumi engine Written by Peter Sovietov in 2015
+ * Ported to rockbox '2019 by Roman Stolyarov
+ *
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
+ * KIND, either express or implied.
+ *
+ ****************************************************************************/
+
+#include <codecs/lib/codeclib.h>
+#include "libayumi/ayumi_render.h" 
+
+CODEC_HEADER
+
+#define VTX_SAMPLE_RATE 44100
+
+/* Maximum number of bytes to process in one iteration */
+#define CHUNK_SIZE (1024*2)
+
+static int16_t samples[CHUNK_SIZE] IBSS_ATTR;
+extern ayumi_render_t ay;
+
+/****************** rockbox interface ******************/
+
+/* this is the codec entry point */
+enum codec_status codec_main(enum codec_entry_call_reason reason)
+{
+    if (reason == CODEC_LOAD) {
+        /* we only render 16 bits */
+        ci->configure(DSP_SET_SAMPLE_DEPTH, 16);
+
+        /* 44 Khz, Interleaved stereo */
+        ci->configure(DSP_SET_FREQUENCY, VTX_SAMPLE_RATE);
+        ci->configure(DSP_SET_STEREO_MODE, STEREO_INTERLEAVED);
+    }
+
+    return CODEC_OK;
+}
+
+/* this is called for each file to process */
+enum codec_status codec_run(void)
+{
+    uint8_t *buf;
+    size_t n;
+    intptr_t param;
+    uint32_t elapsed_time;
+    long smp;
+    int res;
+
+    /* reset values */
+    elapsed_time = 0;
+    param = ci->id3->elapsed;
+
+    DEBUGF("VTX: next_track\n");
+    if (codec_init()) {
+        return CODEC_ERROR;
+    }  
+
+    codec_set_replaygain(ci->id3);
+
+    /* Read the entire file */
+    DEBUGF("VTX: request file\n");
+    ci->seek_buffer(0);
+    buf = ci->request_buffer(&n, ci->filesize);
+    if (!buf || n < (size_t)ci->filesize) {
+        DEBUGF("VTX: file load failed\n");
+        return CODEC_ERROR;
+    }
+
+    res = AyumiRender_LoadFile((void *)buf, ci->filesize);
+    if (!res) {
+        DEBUGF("VTX: AyumiRender_LoadFile failed\n");
+        return CODEC_ERROR;
+    }
+
+    res = AyumiRender_AyInit(ay.info.chiptype, VTX_SAMPLE_RATE, ay.info.chipfreq, ay.info.playerfreq, 1);
+    if (!res) {
+        DEBUGF("VTX: AyumiRender_AyInit failed\n");
+        return CODEC_ERROR;
+    }
+    
+    res = AyumiRender_SetLayout(ay.info.layout, 0);
+    if (!res) {
+        DEBUGF("VTX: AyumiRender_SetLayout failed\n");
+        return CODEC_ERROR;
+    }
+
+    if (param) {
+        goto resume_start;
+    }
+
+    /* The main decoder loop */
+    while (1) {
+        long action = ci->get_command(&param);
+
+        if (action == CODEC_ACTION_HALT)
+            break;
+
+        if (action == CODEC_ACTION_SEEK_TIME) {
+        resume_start:
+            ci->set_elapsed(param);
+            elapsed_time = param;
+            ulong sample = ((ulong)elapsed_time * 441) / 10;
+            AyumiRender_Seek(sample);
+            ci->seek_complete();
+        }
+    
+        /* Generate audio buffer */
+        smp = AyumiRender_AySynth((void *)&samples[0], CHUNK_SIZE >> 1);
+
+        ci->pcmbuf_insert(samples, NULL, smp);
+
+        /* Set elapsed time for one track files */
+        elapsed_time += smp * 10 / 441;
+        ci->set_elapsed(elapsed_time);
+
+        if (AyumiRender_GetPos() >= AyumiRender_GetMaxPos())
+            break;
+    }
+
+    return CODEC_OK;
+}