Move bitstream reader to coding_utils

src/coding/coding.h

@@ -276,4 +276,19 @@ void xma2_parse_xma2_chunk(STREAMFILE *streamFile, off_t chunk_offset, int * cha
 size_t atrac3_bytes_to_samples(size_t bytes, int full_block_align);
 size_t atrac3plus_bytes_to_samples(size_t bytes, int full_block_align);
 
+
+
+/* An internal struct to pass around and simulate a bitstream. */
+typedef enum { BITSTREAM_MSF, BITSTREAM_VORBIS } vgm_bitstream_t;
+typedef struct {
+    uint8_t * buf;          /* buffer to read/write*/
+    size_t bufsize;         /* max size of the buffer */
+    off_t b_off;            /* current offset in bits inside the buffer */
+    off_t info_offset;      /* for logging */
+    vgm_bitstream_t mode;   /* read/write modes */
+} vgm_bitstream;
+
+int r_bits(vgm_bitstream * ib, int num_bits, uint32_t * value);
+int w_bits(vgm_bitstream * ob, int num_bits, uint32_t value);
+
 #endif /*_CODING_H*/

src/coding/coding_utils.c

@@ -835,3 +835,149 @@ size_t atrac3plus_bytes_to_samples(size_t bytes, int full_block_align) {
      * so (full_block_align / channels) DOESN'T give the size of a single channel (common in ATRAC3plus) */
     return (bytes / full_block_align) * 2048;
 }
+
+
+/* ******************************************** */
+/* BITSTREAM                                    */
+/* ******************************************** */
+
+
+/* Read bits (max 32) from buf and update the bit offset. Vorbis packs values in LSB order and byte by byte.
+ * (ex. from 2 bytes 00100111 00000001 we can could read 4b=0111 and 6b=010010, 6b=remainder (second value is split into the 2nd byte) */
+static int r_bits_vorbis(vgm_bitstream * ib, int num_bits, uint32_t * value) {
+    off_t off, pos;
+    int i, bit_buf, bit_val;
+    if (num_bits == 0) return 1;
+    if (num_bits > 32 || num_bits < 0 || ib->b_off + num_bits > ib->bufsize*8) goto fail;
+
+    *value = 0; /* set all bits to 0 */
+    off = ib->b_off / 8; /* byte offset */
+    pos = ib->b_off % 8; /* bit sub-offset */
+    for (i = 0; i < num_bits; i++) {
+        bit_buf = (1U << pos) & 0xFF;   /* bit check for buf */
+        bit_val = (1U << i);            /* bit to set in value */
+
+        if (ib->buf[off] & bit_buf)     /* is bit in buf set? */
+            *value |= bit_val;          /* set bit */
+
+        pos++;                          /* new byte starts */
+        if (pos%8 == 0) {
+            pos = 0;
+            off++;
+        }
+    }
+
+    ib->b_off += num_bits;
+    return 1;
+fail:
+    return 0;
+}
+
+/* Write bits (max 32) to buf and update the bit offset. Vorbis packs values in LSB order and byte by byte.
+ * (ex. writing 1101011010 from b_off 2 we get 01101011 00001101 (value split, and 11 in the first byte skipped)*/
+static int w_bits_vorbis(vgm_bitstream * ob, int num_bits, uint32_t value) {
+    off_t off, pos;
+    int i, bit_val, bit_buf;
+    if (num_bits == 0) return 1;
+    if (num_bits > 32 || num_bits < 0 || ob->b_off + num_bits > ob->bufsize*8) goto fail;
+
+
+    off = ob->b_off / 8; /* byte offset */
+    pos = ob->b_off % 8; /* bit sub-offset */
+    for (i = 0; i < num_bits; i++) {
+        bit_val = (1U << i);            /* bit check for value */
+        bit_buf = (1U << pos) & 0xFF;   /* bit to set in buf */
+
+        if (value & bit_val)            /* is bit in val set? */
+            ob->buf[off] |= bit_buf;    /* set bit */
+        else
+            ob->buf[off] &= ~bit_buf;   /* unset bit */
+
+        pos++;                          /* new byte starts */
+        if (pos%8 == 0) {
+            pos = 0;
+            off++;
+        }
+    }
+
+    ob->b_off += num_bits;
+    return 1;
+fail:
+    return 0;
+}
+
+
+/* Read bits (max 32) from buf and update the bit offset. Order is BE (MSF). */
+static int r_bits_msf(vgm_bitstream * ib, int num_bits, uint32_t * value) {
+    off_t off, pos;
+    int i, bit_buf, bit_val;
+    if (num_bits == 0) return 1;
+    if (num_bits > 32 || num_bits < 0 || ib->b_off + num_bits > ib->bufsize*8) goto fail;
+
+    *value = 0; /* set all bits to 0 */
+    off = ib->b_off / 8; /* byte offset */
+    pos = ib->b_off % 8; /* bit sub-offset */
+    for (i = 0; i < num_bits; i++) {
+        bit_buf = (1U << (8-1-pos)) & 0xFF;   /* bit check for buf */
+        bit_val = (1U << (num_bits-1-i));     /* bit to set in value */
+
+        if (ib->buf[off] & bit_buf)         /* is bit in buf set? */
+            *value |= bit_val;              /* set bit */
+
+        pos++;
+        if (pos%8 == 0) {                   /* new byte starts */
+            pos = 0;
+            off++;
+        }
+    }
+
+    ib->b_off += num_bits;
+    return 1;
+fail:
+    return 0;
+}
+
+/* Write bits (max 32) to buf and update the bit offset. Order is BE (MSF). */
+static int w_bits_msf(vgm_bitstream * ob, int num_bits, uint32_t value) {
+    off_t off, pos;
+    int i, bit_val, bit_buf;
+    if (num_bits == 0) return 1;
+    if (num_bits > 32 || num_bits < 0 || ob->b_off + num_bits > ob->bufsize*8) goto fail;
+
+
+    off = ob->b_off / 8; /* byte offset */
+    pos = ob->b_off % 8; /* bit sub-offset */
+    for (i = 0; i < num_bits; i++) {
+        bit_val = (1U << (num_bits-1-i));     /* bit check for value */
+        bit_buf = (1U << (8-1-pos)) & 0xFF;   /* bit to set in buf */
+
+        if (value & bit_val)                /* is bit in val set? */
+            ob->buf[off] |= bit_buf;        /* set bit */
+        else
+            ob->buf[off] &= ~bit_buf;       /* unset bit */
+
+        pos++;
+        if (pos%8 == 0) {                   /* new byte starts */
+            pos = 0;
+            off++;
+        }
+    }
+
+    ob->b_off += num_bits;
+    return 1;
+fail:
+    return 0;
+}
+
+int r_bits(vgm_bitstream * ib, int num_bits, uint32_t * value) {
+    if (ib->mode == BITSTREAM_VORBIS)
+        return r_bits_vorbis(ib,num_bits,value);
+    else
+        return r_bits_msf(ib,num_bits,value);
+}
+int w_bits(vgm_bitstream * ob, int num_bits, uint32_t value) {
+    if (ob->mode == BITSTREAM_VORBIS)
+        return w_bits_vorbis(ob,num_bits,value);
+    else
+        return w_bits_msf(ob,num_bits,value);
+}

src/coding/mpeg_custom_utils_ealayer3.c

@@ -25,14 +25,6 @@
 #define EALAYER3_MAX_GRANULES  2
 #define EALAYER3_MAX_CHANNELS  2
 
-/* helper to simulate a bitstream */
-typedef struct {
-    uint8_t * buf;      /* buffer to read/write*/
-    size_t bufsize;     /* max size of the buffer */
-    off_t b_off;        /* current offset in bits inside the buffer */
-    off_t info_offset;  /* for logs */
-} ealayer3_bitstream;
-
 /* parsed info from a single EALayer3 frame */
 typedef struct {
     /* EALayer3 v1 header */
@@ -81,18 +73,14 @@ typedef struct {
 } ealayer3_frame_info;
 
 
-static int ealayer3_parse_frame(mpeg_codec_data *data, ealayer3_bitstream *is, ealayer3_frame_info * eaf);
+static int ealayer3_parse_frame(mpeg_codec_data *data, vgm_bitstream *is, ealayer3_frame_info * eaf);
-static int ealayer3_parse_frame_v1(ealayer3_bitstream *is, ealayer3_frame_info * eaf, int channels_per_frame, int is_v1b);
+static int ealayer3_parse_frame_v1(vgm_bitstream *is, ealayer3_frame_info * eaf, int channels_per_frame, int is_v1b);
-static int ealayer3_parse_frame_v2(ealayer3_bitstream *is, ealayer3_frame_info * eaf);
+static int ealayer3_parse_frame_v2(vgm_bitstream *is, ealayer3_frame_info * eaf);
-static int ealayer3_parse_frame_common(ealayer3_bitstream *is, ealayer3_frame_info * eaf);
+static int ealayer3_parse_frame_common(vgm_bitstream *is, ealayer3_frame_info * eaf);
-static int ealayer3_rebuild_mpeg_frame(ealayer3_bitstream* is_0, ealayer3_frame_info* eaf_0, ealayer3_bitstream* is_1, ealayer3_frame_info* eaf_1, ealayer3_bitstream* os);
+static int ealayer3_rebuild_mpeg_frame(vgm_bitstream* is_0, ealayer3_frame_info* eaf_0, vgm_bitstream* is_1, ealayer3_frame_info* eaf_1, vgm_bitstream* os);
 static int ealayer3_write_pcm_block(VGMSTREAMCHANNEL *stream, mpeg_codec_data *data, int num_stream, ealayer3_frame_info * eaf);
 static int ealayer3_skip_data(VGMSTREAMCHANNEL *stream, mpeg_codec_data *data, int num_stream, int at_start);
 
-static int r_bits(ealayer3_bitstream * iw, int num_bits, uint32_t * value);
-static int w_bits(ealayer3_bitstream * ow, int num_bits, uint32_t value);
-
-
 /* **************************************************************************** */
 /* EXTERNAL API                                                                 */
 /* **************************************************************************** */
@@ -101,7 +89,7 @@ static int w_bits(ealayer3_bitstream * ow, int num_bits, uint32_t value);
 int mpeg_custom_setup_init_ealayer3(STREAMFILE *streamFile, off_t start_offset, mpeg_codec_data *data, coding_t *coding_type) {
     int ok;
     ealayer3_frame_info eaf;
-    ealayer3_bitstream is = {0};
+    vgm_bitstream is = {0};
     uint8_t ibuf[EALAYER3_EA_FRAME_BUFFER_SIZE];
 
     //;VGM_LOG("init at %lx\n", start_offset);
@@ -135,7 +123,7 @@ int mpeg_custom_parse_frame_ealayer3(VGMSTREAMCHANNEL *stream, mpeg_codec_data *
     off_t info_offset = stream->offset;
 
     ealayer3_frame_info eaf_0, eaf_1;
-    ealayer3_bitstream is_0 = {0}, is_1 = {0}, os = {0};
+    vgm_bitstream is_0 = {0}, is_1 = {0}, os = {0};
     uint8_t ibuf_0[EALAYER3_EA_FRAME_BUFFER_SIZE], ibuf_1[EALAYER3_EA_FRAME_BUFFER_SIZE];
 
     /* read first frame/granule, or PCM-only frame (found alone at the end of SCHl streams) */
@@ -213,7 +201,7 @@ fail:
 /* INTERNAL HELPERS                                                             */
 /* **************************************************************************** */
 
-static int ealayer3_parse_frame(mpeg_codec_data *data, ealayer3_bitstream *is, ealayer3_frame_info * eaf) {
+static int ealayer3_parse_frame(mpeg_codec_data *data, vgm_bitstream *is, ealayer3_frame_info * eaf) {
     int ok;
 
     /* make sure as there is re-parsing in loops */
@@ -235,7 +223,7 @@ fail:
 
 
 /* read V1"a" (in SCHl) and V1"b" (in SNS) EALayer3 frame */
-static int ealayer3_parse_frame_v1(ealayer3_bitstream *is, ealayer3_frame_info * eaf, int channels_per_frame, int is_v1b) {
+static int ealayer3_parse_frame_v1(vgm_bitstream *is, ealayer3_frame_info * eaf, int channels_per_frame, int is_v1b) {
     int ok;
 
     /* read EA-frame V1 header */
@@ -282,7 +270,7 @@ fail:
 
 /* read V2"PCM" and V2"Spike" EALayer3 frame (exactly the same but V2P seems to have bigger
  * PCM blocks and maybe smaller frames) */
-static int ealayer3_parse_frame_v2(ealayer3_bitstream *is, ealayer3_frame_info * eaf) {
+static int ealayer3_parse_frame_v2(vgm_bitstream *is, ealayer3_frame_info * eaf) {
     int ok;
 
     /* read EA-frame V2 header */
@@ -328,7 +316,7 @@ fail:
 
 
 /* parses an EALayer3 frame (common part) */
-static int ealayer3_parse_frame_common(ealayer3_bitstream *is, ealayer3_frame_info * eaf) {
+static int ealayer3_parse_frame_common(vgm_bitstream *is, ealayer3_frame_info * eaf) {
     /* index tables */
     static const int versions[4] = { /* MPEG 2.5 */ 3, /* reserved */ -1,  /* MPEG 2 */ 2, /* MPEG 1 */ 1 };
     static const int sample_rates[4][4] = { /* [version_index][sample rate index] */
@@ -412,7 +400,7 @@ fail:
 
 
 /* converts an EALAYER3 frame to a standard MPEG frame from pre-parsed info */
-static int ealayer3_rebuild_mpeg_frame(ealayer3_bitstream* is_0, ealayer3_frame_info* eaf_0, ealayer3_bitstream* is_1, ealayer3_frame_info* eaf_1, ealayer3_bitstream* os) {
+static int ealayer3_rebuild_mpeg_frame(vgm_bitstream* is_0, ealayer3_frame_info* eaf_0, vgm_bitstream* is_1, ealayer3_frame_info* eaf_1, vgm_bitstream* os) {
     uint32_t c = 0;
     int i,j;
     int expected_bitrate_index, expected_frame_size;
@@ -663,7 +651,7 @@ fail:
 static int ealayer3_skip_data(VGMSTREAMCHANNEL *stream, mpeg_codec_data *data, int num_stream, int at_start) {
     int ok, i;
     ealayer3_frame_info eaf;
-    ealayer3_bitstream is = {0};
+    vgm_bitstream is = {0};
     uint8_t ibuf[EALAYER3_EA_FRAME_BUFFER_SIZE];
     int skips = at_start ? num_stream : data->streams_size - 1 - num_stream;
 
@@ -685,68 +673,4 @@ fail:
     return 0;
 }
 
-/* ********************************************* */
-
-/* Read bits (max 32) from buf and update the bit offset. Order is BE (MSF). */
-static int r_bits(ealayer3_bitstream * is, int num_bits, uint32_t * value) {
-    off_t off, pos;
-    int i, bit_buf, bit_val;
-    if (num_bits == 0) return 1;
-    if (num_bits > 32 || num_bits < 0 || is->b_off + num_bits > is->bufsize*8) goto fail;
-
-    *value = 0; /* set all bits to 0 */
-    off = is->b_off / 8; /* byte offset */
-    pos = is->b_off % 8; /* bit sub-offset */
-    for (i = 0; i < num_bits; i++) {
-        bit_buf = (1U << (8-1-pos)) & 0xFF;   /* bit check for buf */
-        bit_val = (1U << (num_bits-1-i));     /* bit to set in value */
-
-        if (is->buf[off] & bit_buf)         /* is bit in buf set? */
-            *value |= bit_val;              /* set bit */
-
-        pos++;
-        if (pos%8 == 0) {                   /* new byte starts */
-            pos = 0;
-            off++;
-        }
-    }
-
-    is->b_off += num_bits;
-    return 1;
-fail:
-    return 0;
-}
-
-/* Write bits (max 32) to buf and update the bit offset. Order is BE (MSF). */
-static int w_bits(ealayer3_bitstream * os, int num_bits, uint32_t value) {
-    off_t off, pos;
-    int i, bit_val, bit_buf;
-    if (num_bits == 0) return 1;
-    if (num_bits > 32 || num_bits < 0 || os->b_off + num_bits > os->bufsize*8) goto fail;
-
-
-    off = os->b_off / 8; /* byte offset */
-    pos = os->b_off % 8; /* bit sub-offset */
-    for (i = 0; i < num_bits; i++) {
-        bit_val = (1U << (num_bits-1-i));     /* bit check for value */
-        bit_buf = (1U << (8-1-pos)) & 0xFF;   /* bit to set in buf */
-
-        if (value & bit_val)                /* is bit in val set? */
-            os->buf[off] |= bit_buf;        /* set bit */
-        else
-            os->buf[off] &= ~bit_buf;       /* unset bit */
-
-        pos++;
-        if (pos%8 == 0) {                   /* new byte starts */
-            pos = 0;
-            off++;
-        }
-    }
-
-    os->b_off += num_bits;
-    return 1;
-fail:
-    return 0;
-}
-
 #endif

src/coding/mpeg_decoder.h

@@ -2,6 +2,7 @@
 #define _MPEG_DECODER_H_
 
 #include "../vgmstream.h"
+#include "../coding/coding.h"
 
 /* used by mpeg_decoder.c, but scattered in other .c files */
 #ifdef VGM_USE_MPEG

src/coding/vorbis_custom_decoder.h

@@ -2,6 +2,7 @@
 #define _VORBIS_CUSTOM_DECODER_H_
 
 #include "../vgmstream.h"
+#include "../coding/coding.h"
 
 /* used by vorbis_custom_decoder.c, but scattered in other .c files */
 #ifdef VGM_USE_VORBIS

src/coding/vorbis_custom_utils_vid1.c

@@ -8,15 +8,6 @@
 /* DEFS                                                                         */
 /* **************************************************************************** */
 
-/* An internal struct to pass around and simulate a bitstream. */
-typedef struct {
-    uint8_t * buf;      /* buffer to read/write*/
-    size_t bufsize;     /* max size of the buffer */
-    off_t b_off;        /* current offset in bits inside the buffer */
-} vgm_bitstream;
-
-static int r_bits(vgm_bitstream * iw, int num_bits, uint32_t * value);
-
 static int get_packet_header(STREAMFILE *streamFile, off_t *offset, size_t *size);
 static int build_header_comment(uint8_t * buf, size_t bufsize);
 
@@ -137,6 +128,7 @@ static int get_packet_header(STREAMFILE *streamFile, off_t *offset, size_t *size
     ib.buf = ibuf;
     ib.bufsize = ibufsize;
     ib.b_off = 0;
+    ib.mode = BITSTREAM_VORBIS;
 
     /* read using Vorbis weird LSF */
     r_bits(&ib,  4,&size_bits);
@@ -157,35 +149,4 @@ fail:
     return 0;
 }
 
-/* Read bits (max 32) from buf and update the bit offset. Vorbis packs values in LSB order and byte by byte.
- * (ex. from 2 bytes 00100111 00000001 we can could read 4b=0111 and 6b=010010, 6b=remainder (second value is split into the 2nd byte) */
-static int r_bits(vgm_bitstream * ib, int num_bits, uint32_t * value) {
-    off_t off, pos;
-    int i, bit_buf, bit_val;
-    if (num_bits == 0) return 1;
-    if (num_bits > 32 || num_bits < 0 || ib->b_off + num_bits > ib->bufsize*8) goto fail;
-
-    *value = 0; /* set all bits to 0 */
-    off = ib->b_off / 8; /* byte offset */
-    pos = ib->b_off % 8; /* bit sub-offset */
-    for (i = 0; i < num_bits; i++) {
-        bit_buf = (1U << pos) & 0xFF;   /* bit check for buf */
-        bit_val = (1U << i);            /* bit to set in value */
-
-        if (ib->buf[off] & bit_buf)     /* is bit in buf set? */
-            *value |= bit_val;          /* set bit */
-
-        pos++;                          /* new byte starts */
-        if (pos%8 == 0) {
-            pos = 0;
-            off++;
-        }
-    }
-
-    ib->b_off += num_bits;
-    return 1;
-fail:
-    return 0;
-}
-
 #endif

src/coding/vorbis_custom_utils_wwise.c

@@ -13,25 +13,17 @@
 /* DEFS                                                                         */
 /* **************************************************************************** */
 
-/* An internal struct to pass around and simulate a bitstream.
- * Mainly to keep code cleaner and somewhat closer to ww2ogg */
-typedef struct {
-    uint8_t * buf;      /* buffer to read/write*/
-    size_t bufsize;     /* max size of the buffer */
-    off_t b_off;        /* current offset in bits inside the buffer */
-} ww_bitstream;
-
 static int build_header_identification(uint8_t * buf, size_t bufsize, int channels, int sample_rate, int blocksize_short, int blocksize_long);
 static int build_header_comment(uint8_t * buf, size_t bufsize);
 static int get_packet_header(STREAMFILE *streamFile, off_t offset, wwise_header_t header_type, int * granulepos, size_t * packet_size, int big_endian);
 static int rebuild_packet(uint8_t * obuf, size_t obufsize, STREAMFILE *streamFile, off_t offset, vorbis_custom_codec_data * data, int big_endian);
 static int rebuild_setup(uint8_t * obuf, size_t obufsize, STREAMFILE *streamFile, off_t offset, vorbis_custom_codec_data * data, int big_endian, int channels);
 
-static int ww2ogg_generate_vorbis_packet(ww_bitstream * ow, ww_bitstream * iw, STREAMFILE *streamFile, off_t offset, vorbis_custom_codec_data * data, int big_endian);
+static int ww2ogg_generate_vorbis_packet(vgm_bitstream * ow, vgm_bitstream * iw, STREAMFILE *streamFile, off_t offset, vorbis_custom_codec_data * data, int big_endian);
-static int ww2ogg_generate_vorbis_setup(ww_bitstream * ow, ww_bitstream * iw, vorbis_custom_codec_data * data, int channels, size_t packet_size, STREAMFILE *streamFile);
+static int ww2ogg_generate_vorbis_setup(vgm_bitstream * ow, vgm_bitstream * iw, vorbis_custom_codec_data * data, int channels, size_t packet_size, STREAMFILE *streamFile);
-static int ww2ogg_codebook_library_copy(ww_bitstream * ow, ww_bitstream * iw);
+static int ww2ogg_codebook_library_copy(vgm_bitstream * ow, vgm_bitstream * iw);
-static int ww2ogg_codebook_library_rebuild(ww_bitstream * ow, ww_bitstream * iw, size_t cb_size, STREAMFILE *streamFile);
+static int ww2ogg_codebook_library_rebuild(vgm_bitstream * ow, vgm_bitstream * iw, size_t cb_size, STREAMFILE *streamFile);
-static int ww2ogg_codebook_library_rebuild_by_id(ww_bitstream * ow, uint32_t codebook_id, wwise_setup_t setup_type, STREAMFILE *streamFile);
+static int ww2ogg_codebook_library_rebuild_by_id(vgm_bitstream * ow, uint32_t codebook_id, wwise_setup_t setup_type, STREAMFILE *streamFile);
 static int ww2ogg_tremor_ilog(unsigned int v);
 static unsigned int ww2ogg_tremor_book_maptype1_quantvals(unsigned int entries, unsigned int dimensions);
 
@@ -39,9 +31,6 @@ static int load_wvc(uint8_t * ibuf, size_t ibufsize, uint32_t codebook_id, wwise
 static int load_wvc_file(uint8_t * buf, size_t bufsize, uint32_t codebook_id, STREAMFILE *streamFile);
 static int load_wvc_array(uint8_t * buf, size_t bufsize, uint32_t codebook_id, wwise_setup_t setup_type);
 
-static int r_bits(ww_bitstream * iw, int num_bits, uint32_t * value);
-static int w_bits(ww_bitstream * ow, int num_bits, uint32_t value);
-
 
 /* **************************************************************************** */
 /* EXTERNAL API                                                                 */
@@ -165,7 +154,7 @@ static int get_packet_header(STREAMFILE *streamFile, off_t offset, wwise_header_
 
 /* Transforms a Wwise data packet into a real Vorbis one (depending on config) */
 static int rebuild_packet(uint8_t * obuf, size_t obufsize, STREAMFILE *streamFile, off_t offset, vorbis_custom_codec_data * data, int big_endian) {
-    ww_bitstream ow, iw;
+    vgm_bitstream ow, iw;
     int rc, granulepos;
     size_t header_size, packet_size;
 
@@ -183,11 +172,13 @@ static int rebuild_packet(uint8_t * obuf, size_t obufsize, STREAMFILE *streamFil
     /* prepare helper structs */
     ow.buf = obuf;
     ow.bufsize = obufsize;
-    ow.b_off = 0 ;
+    ow.b_off = 0;
+    ow.mode = BITSTREAM_VORBIS;
 
     iw.buf = ibuf;
     iw.bufsize = ibufsize;
     iw.b_off = 0;
+    iw.mode = BITSTREAM_VORBIS;
 
     rc = ww2ogg_generate_vorbis_packet(&ow,&iw, streamFile,offset, data, big_endian);
     if (!rc) goto fail;
@@ -206,7 +197,7 @@ fail:
 
 /* Transforms a Wwise setup packet into a real Vorbis one (depending on config). */
 static int rebuild_setup(uint8_t * obuf, size_t obufsize, STREAMFILE *streamFile, off_t offset, vorbis_custom_codec_data * data, int big_endian, int channels) {
-    ww_bitstream ow, iw;
+    vgm_bitstream ow, iw;
     int rc, granulepos;
     size_t header_size, packet_size;
 
@@ -226,10 +217,12 @@ static int rebuild_setup(uint8_t * obuf, size_t obufsize, STREAMFILE *streamFile
     ow.buf = obuf;
     ow.bufsize = obufsize;
     ow.b_off = 0;
+    ow.mode = BITSTREAM_VORBIS;
 
     iw.buf = ibuf;
     iw.bufsize = ibufsize;
     iw.b_off = 0;
+    iw.mode = BITSTREAM_VORBIS;
 
     rc = ww2ogg_generate_vorbis_setup(&ow,&iw, data, channels, packet_size, streamFile);
     if (!rc) goto fail;
@@ -295,7 +288,7 @@ static int build_header_comment(uint8_t * buf, size_t bufsize) {
 
 /* Copy packet as-is or rebuild first byte if mod_packets is used.
  * (ref: https://www.xiph.org/vorbis/doc/Vorbis_I_spec.html#x1-720004.3) */
-static int ww2ogg_generate_vorbis_packet(ww_bitstream * ow, ww_bitstream * iw, STREAMFILE *streamFile, off_t offset, vorbis_custom_codec_data * data, int big_endian) {
+static int ww2ogg_generate_vorbis_packet(vgm_bitstream * ow, vgm_bitstream * iw, STREAMFILE *streamFile, off_t offset, vorbis_custom_codec_data * data, int big_endian) {
     int i,granule;
     size_t header_size, packet_size, data_size;
 
@@ -350,10 +343,13 @@ static int ww2ogg_generate_vorbis_packet(ww_bitstream * ow, ww_bitstream * iw, S
                     /* get next first byte to read next_mode_number */
                     uint32_t next_mode_number;
                     uint8_t nbuf[1];
-                    ww_bitstream nw;
+                    vgm_bitstream nw;
+
                     nw.buf = nbuf;
                     nw.bufsize = 1;
                     nw.b_off = 0;
+                    nw.mode = BITSTREAM_VORBIS;
+
 
                     if (read_streamfile(nw.buf, next_offset + next_header_size, nw.bufsize, streamFile) != nw.bufsize)
                         goto fail;
@@ -409,7 +405,7 @@ fail:
 
 /* Rebuild a Wwise setup (simplified with removed stuff), recreating all six setup parts.
  * (ref: https://www.xiph.org/vorbis/doc/Vorbis_I_spec.html#x1-650004.2.4) */
-static int ww2ogg_generate_vorbis_setup(ww_bitstream * ow, ww_bitstream * iw, vorbis_custom_codec_data * data, int channels, size_t packet_size, STREAMFILE *streamFile) {
+static int ww2ogg_generate_vorbis_setup(vgm_bitstream * ow, vgm_bitstream * iw, vorbis_custom_codec_data * data, int channels, size_t packet_size, STREAMFILE *streamFile) {
     int i,j,k;
     uint32_t codebook_count = 0, floor_count = 0, residue_count = 0;
     uint32_t codebook_count_less1 = 0;
@@ -798,7 +794,7 @@ fail:
 
 
 /* copies Vorbis codebooks (untouched, but size uncertain) */
-static int ww2ogg_codebook_library_copy(ww_bitstream * ow, ww_bitstream * iw) {
+static int ww2ogg_codebook_library_copy(vgm_bitstream * ow, vgm_bitstream * iw) {
     int i;
     uint32_t id = 0, dimensions = 0, entries = 0;
     uint32_t ordered = 0, lookup_type = 0;
@@ -914,7 +910,7 @@ fail:
 
 
 /* rebuilds a Wwise codebook into a Vorbis codebook */
-static int ww2ogg_codebook_library_rebuild(ww_bitstream * ow, ww_bitstream * iw, size_t cb_size, STREAMFILE *streamFile) {
+static int ww2ogg_codebook_library_rebuild(vgm_bitstream * ow, vgm_bitstream * iw, size_t cb_size, STREAMFILE *streamFile) {
     int i;
     uint32_t id = 0, dimensions = 0, entries = 0;
     uint32_t ordered = 0, lookup_type = 0;
@@ -1038,11 +1034,11 @@ fail:
 }
 
 /* rebuilds an external Wwise codebook referenced by id to a Vorbis codebook */
-static int ww2ogg_codebook_library_rebuild_by_id(ww_bitstream * ow, uint32_t codebook_id, wwise_setup_t setup_type, STREAMFILE *streamFile) {
+static int ww2ogg_codebook_library_rebuild_by_id(vgm_bitstream * ow, uint32_t codebook_id, wwise_setup_t setup_type, STREAMFILE *streamFile) {
     size_t ibufsize = 0x8000; /* arbitrary max size of a codebook */
     uint8_t ibuf[0x8000]; /* Wwise codebook buffer */
     size_t cb_size;
-    ww_bitstream iw;
+    vgm_bitstream iw;
 
     cb_size = load_wvc(ibuf,ibufsize, codebook_id, setup_type, streamFile);
     if (cb_size == 0) goto fail;
@@ -1050,6 +1046,7 @@ static int ww2ogg_codebook_library_rebuild_by_id(ww_bitstream * ow, uint32_t cod
     iw.buf = ibuf;
     iw.bufsize = ibufsize;
     iw.b_off = 0;
+    iw.mode = BITSTREAM_VORBIS;
 
     return ww2ogg_codebook_library_rebuild(ow, &iw, cb_size, streamFile);
 fail:
@@ -1228,70 +1225,4 @@ fail:
     return 0;
 }
 
-/* ********************************************* */
-
-/* Read bits (max 32) from buf and update the bit offset. Vorbis packs values in LSB order and byte by byte.
- * (ex. from 2 bytes 00100111 00000001 we can could read 4b=0111 and 6b=010010, 6b=remainder (second value is split into the 2nd byte) */
-static int r_bits(ww_bitstream * iw, int num_bits, uint32_t * value) {
-    off_t off, pos;
-    int i, bit_buf, bit_val;
-    if (num_bits == 0) return 1;
-    if (num_bits > 32 || num_bits < 0 || iw->b_off + num_bits > iw->bufsize*8) goto fail;
-
-    *value = 0; /* set all bits to 0 */
-    off = iw->b_off / 8; /* byte offset */
-    pos = iw->b_off % 8; /* bit sub-offset */
-    for (i = 0; i < num_bits; i++) {
-        bit_buf = (1U << pos) & 0xFF;   /* bit check for buf */
-        bit_val = (1U << i);            /* bit to set in value */
-
-        if (iw->buf[off] & bit_buf)     /* is bit in buf set? */
-            *value |= bit_val;          /* set bit */
-
-        pos++;                          /* new byte starts */
-        if (pos%8 == 0) {
-            pos = 0;
-            off++;
-        }
-    }
-
-    iw->b_off += num_bits;
-    return 1;
-fail:
-    return 0;
-}
-
-/* Write bits (max 32) to buf and update the bit offset. Vorbis packs values in LSB order and byte by byte.
- * (ex. writing 1101011010 from b_off 2 we get 01101011 00001101 (value split, and 11 in the first byte skipped)*/
-static int w_bits(ww_bitstream * ow, int num_bits, uint32_t value) {
-    off_t off, pos;
-    int i, bit_val, bit_buf;
-    if (num_bits == 0) return 1;
-    if (num_bits > 32 || num_bits < 0 || ow->b_off + num_bits > ow->bufsize*8) goto fail;
-
-
-    off = ow->b_off / 8; /* byte offset */
-    pos = ow->b_off % 8; /* bit sub-offset */
-    for (i = 0; i < num_bits; i++) {
-        bit_val = (1U << i);            /* bit check for value */
-        bit_buf = (1U << pos) & 0xFF;   /* bit to set in buf */
-
-        if (value & bit_val)            /* is bit in val set? */
-            ow->buf[off] |= bit_buf;    /* set bit */
-        else
-            ow->buf[off] &= ~bit_buf;   /* unset bit */
-
-        pos++;                          /* new byte starts */
-        if (pos%8 == 0) {
-            pos = 0;
-            off++;
-        }
-    }
-
-    ow->b_off += num_bits;
-    return 1;
-fail:
-    return 0;
-}
-
 #endif