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-rw-r--r--src/lib/formats/ap2_dsk.cpp168
1 files changed, 168 insertions, 0 deletions
diff --git a/src/lib/formats/ap2_dsk.cpp b/src/lib/formats/ap2_dsk.cpp
index 374ecc4a060..1a2e2a65e68 100644
--- a/src/lib/formats/ap2_dsk.cpp
+++ b/src/lib/formats/ap2_dsk.cpp
@@ -1746,3 +1746,171 @@ uint32_t a2_woz_format::crc32r(const uint8_t *data, uint32_t size)
const floppy_format_type FLOPPY_WOZ_FORMAT = &floppy_image_format_creator<a2_woz_format>;
+
+
+a2_nib_format::a2_nib_format() : floppy_image_format_t()
+{
+}
+
+const char *a2_nib_format::name() const
+{
+ return "a2_nib";
+}
+
+const char *a2_nib_format::description() const
+{
+ return "Apple II NIB Image";
+}
+
+const char *a2_nib_format::extensions() const
+{
+ return "nib";
+}
+
+bool a2_nib_format::supports_save() const
+{
+ return false;
+}
+
+int a2_nib_format::identify(io_generic *io, uint32_t form_factor, const std::vector<uint32_t> &variants)
+{
+ const auto size = io_generic_size(io);
+ if (size == expected_size_35t || size == expected_size_40t) {
+ return 50;
+ }
+ return 0;
+}
+
+
+template<class It>
+static
+size_t count_leading_FFs(const It first, const It last)
+{
+ auto curr = first;
+ for (; curr != last; ++curr) {
+ if (*curr != 0xFF) {
+ break;
+ }
+ }
+ return curr - first;
+}
+
+static
+size_t count_trailing_padding(const std::vector<uint8_t>& nibbles) {
+ const auto b = nibbles.rbegin();
+ const auto e = nibbles.rend();
+ auto i = b;
+
+ // skip until the first valid nibble...
+ for (; i != e; ++i) {
+ if ((*i & 0x80) != 0) { // valid nibble
+ break;
+ }
+ }
+ return i - b;
+}
+
+std::vector<uint32_t> a2_nib_format::generate_levels_from_nibbles(const std::vector<uint8_t>& nibbles)
+{
+ std::vector<uint32_t> levels;
+ const auto append_FFs = [&] (size_t count) {
+ while (count-- > 0) {
+ raw_w(levels, 8, 0xFF);
+ }
+ };
+ const auto append_syncs = [&] (size_t count) {
+ while (count-- > 0) {
+ raw_w(levels, 10, 0x00FF << 2);
+ }
+ };
+ const auto append_byte = [&] (uint8_t byte) {
+ raw_w(levels, 8, byte);
+ };
+
+
+ const auto leading_FF_count =
+ count_leading_FFs(nibbles.begin(), nibbles.end());
+
+ if (leading_FF_count >= nibbles.size()) { // all are 0xFF !?!?
+ assert(leading_FF_count >= min_sync_bytes);
+ append_syncs(leading_FF_count);
+ return levels;
+ }
+
+ const auto trailing_padding_size = count_trailing_padding(nibbles);
+ const auto trailing_FF_count =
+ count_leading_FFs(nibbles.rbegin() + trailing_padding_size,
+ nibbles.rend());
+ const auto wrapped_FF_count = leading_FF_count + trailing_FF_count;
+ const bool wrapped_FF_are_syncs = wrapped_FF_count >= min_sync_bytes;
+
+ if (wrapped_FF_are_syncs) {
+ append_syncs(leading_FF_count);
+ } else {
+ append_FFs(leading_FF_count);
+ }
+
+ {
+ size_t FF_count = 0;
+ const auto flush_FFs = [&] {
+ if (FF_count == 0) {
+ return;
+ }
+
+ if (FF_count >= a2_nib_format::min_sync_bytes) {
+ append_syncs(FF_count);
+ } else {
+ append_FFs(FF_count);
+ }
+ FF_count = 0;
+ };
+
+ const auto end = nibbles.end() - trailing_padding_size - trailing_FF_count;
+ for (auto i = nibbles.begin() + leading_FF_count; i != end; ++i) {
+ const auto nibble = *i;
+ if ((nibble & 0x80) == 0) {
+ continue;
+ }
+
+ if (nibble == 0xFF) {
+ ++FF_count;
+ continue;
+ }
+
+ flush_FFs();
+ append_byte(nibble);
+ }
+ flush_FFs();
+ }
+
+ if (wrapped_FF_are_syncs) {
+ append_syncs(trailing_FF_count);
+ } else {
+ append_FFs(trailing_FF_count);
+ }
+
+ return levels;
+}
+
+bool a2_nib_format::load(io_generic *io, uint32_t form_factor, const std::vector<uint32_t> &variants, floppy_image *image)
+{
+ auto size = io_generic_size(io);
+ if (size != expected_size_35t && size != expected_size_40t) {
+ return false;
+ }
+ const auto nr_tracks = size == expected_size_35t? 35 : 40;
+
+ std::vector<uint8_t> nibbles(nibbles_per_track);
+ for (unsigned track = 0; track < nr_tracks; ++track) {
+ io_generic_read(io, &nibbles[0],
+ track * nibbles_per_track, nibbles_per_track);
+ auto levels = generate_levels_from_nibbles(nibbles);
+ generate_track_from_levels(track, 0,
+ levels,
+ 0, image);
+ }
+ return true;
+}
+
+
+const floppy_format_type FLOPPY_NIB_FORMAT = &floppy_image_format_creator<a2_nib_format>;