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https://github.com/libretro/fuse-libretro.git
synced 2026-11-07 10:36:03 -10:00
libretro: detect 128K content loaded on a 48K model
The Model option defaults to Spectrum 48K, matching Fuse's own default
in settings.c. A 128K-only release loaded on a 48K machine then does
what it would do on real hardware: it loads, and dies on a garbled
screen with no way out. Standalone Fuse remembers the machine the user
last picked in its config file, so the same tape "just works" there and
the core looks broken by comparison.
That is fuse-libretro#157, reported against the 128K release of Army
Moves: verified as not a core defect - the tape loads and plays on
128K/+2/+3, on current master and on cad85b7 (the tree at the time of
the report) alike, with identical frame signatures - but the failure
gives the user nothing at all to go on.
Add content detection that runs before fuse_init(), i.e. before
settings_init() -> update_variables(1) turns the Model option into
settings_current.start_machine. A tape counts as 128K-only when:
- it carries a TZX block 0x2A, "stop the tape if in 48K mode";
- it carries a TZX block 0x33 hardware record either ruling out a
16K/48K machine (value 3) or flagging use of 128K/+2/+3 hardware
(value 1);
- or its filename tags it as the 128K release, which is how the
common naming conventions mark it, and how Army Moves - which has
neither in-tape marker - is caught.
Only a standalone 128 counts, so "Bruce Lee - 1280 bytes" does not
match, and directory components are ignored so a tape does not become a
128K release by living in a folder called "128K Games". Snapshots are
deliberately not considered: those carry their own machine and Fuse
switches to it by itself.
By default this changes nothing except that the core now says what to
do, on screen and in the log. The new fuse_auto_machine option (default
disabled) additionally selects a Spectrum 128K for such content when
Model is set to a 48K-class machine, leaving every other Model choice
exactly as set - flipping the default is a one-line change if that is
preferred.
The TZX walk bounds-checks every block before stepping over it and
reads nothing else; identifying and loading the content remains
libspectrum's job. 4000 fuzz cases (random block soup, bit-flipped and
truncated real tapes, noise behind a valid signature) and 3000
adversarial pathnames under ASan/UBSan with -fno-sanitize-recover: no
failures. Behaviour matrix over {48K, 128K, +2, +3, 16K, TC2048} x
{auto on, off} is sanitizer-clean, and the frame signatures for
128K/+2/+3/TC2048 are identical with the option either way.
Also replace the two bare 10s naming TS2068's position in machine_list
with named indices, since the detection needs the 128K one anyway.
This commit is contained in:
libretroadmin authored and libretroadmin committed
1 parent
2fbeeaeac5
commit
94beb76e33
1 file changed
+286
-3
+286
-3
@@ -101,11 +101,26 @@ static const machine_t machine_list[] =
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{ LIBSPECTRUM_MACHINE_SCORP, "scorpion", 0 },
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};
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/* Positions in machine_list, for the places that have to name one. */
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#define MACHINE_IDX_48 0
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#define MACHINE_IDX_48_NTSC 1
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#define MACHINE_IDX_128 2
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#define MACHINE_IDX_TS2068 10
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#define MACHINE_IDX_16 11
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static int machine_id_is_60hz(libspectrum_machine id)
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{
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return id == LIBSPECTRUM_MACHINE_48_NTSC || id == LIBSPECTRUM_MACHINE_TS2068;
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}
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/* The models with no 128K paging and no AY, i.e. the ones a 128K-only
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release cannot run on. */
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static int machine_idx_is_48k_class(int idx)
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{
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return idx == MACHINE_IDX_48 || idx == MACHINE_IDX_48_NTSC ||
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idx == MACHINE_IDX_16;
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}
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#define BGR16(color) rgb32_to_bgr16(color)
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#define rgb32_to_bgr16(color) rgbc32_to_bgr16((color & 0xFF0000) >> 16, (color & 0x00FF00) >> 8, (color & 0x0000FF))
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#define rgbc32_to_bgr16(red, green, blue) ((blue & 0b11111000) << 8) | ((green & 0b11111100) << 3) | (red >> 3)
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@@ -602,6 +617,16 @@ static struct retro_core_option_v2_definition core_option_definitions[] = {
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},
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"Spectrum 48K"
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},
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{
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"fuse_auto_machine",
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"Auto-select Model for 128K content (needs content load)",
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NULL,
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"Load 128K-only releases on a Spectrum 128K even when Model is set to a 48K machine. A tape is treated as 128K-only when it says so itself (a 'stop the tape if in 48K mode' block, or hardware information ruling out a 48K) or when its filename tags it as the 128K release. Leave this disabled to have Model always honoured exactly as set; the core still says so on screen when content looks like it needs a 128K.",
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NULL,
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"system",
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{ CORE_OPTION_VALUE_LIST_ENABLED_DISABLED },
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"disabled"
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},
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{
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"fuse_emulation_speed",
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"Emulation speed percentage (needs content load)",
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@@ -1015,6 +1040,7 @@ static struct retro_core_options_v2 core_options_v2 = {
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static const struct retro_variable core_vars[] =
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{
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{ "fuse_machine", "Model (needs content load); Spectrum 48K|Spectrum 48K (NTSC)|Spectrum 128K|Spectrum +2|Spectrum +2A|Spectrum +3|Spectrum +3e|Spectrum SE|Timex TC2048|Timex TC2068|Timex TS2068|Spectrum 16K|Pentagon 128K|Pentagon 512K|Pentagon 1024|Scorpion 256K" },
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{ "fuse_auto_machine", "Auto-select Model for 128K content (needs content load); disabled|enabled" },
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{ "fuse_emulation_speed", "Emulation speed percentage (needs content load); 100|150|200|300|50"},
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{ "fuse_size_border", "Size Video Border; full|medium|small|minimum|none" },
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{ "fuse_palette", "Colour Palette; Fuse Standard|ZX Standard|B&W TV|Green Monochrome|Ambar Monochrome|C64|CGA 4 colours|CGA 8 colours|CGA 16 colours|Inverted colours"},
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@@ -1852,6 +1878,227 @@ static struct retro_disk_control_ext_callback disk_control_ext_cb = {
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disk_get_image_label,
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};
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/*
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** 128K content detection
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**
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** The Model option defaults to Spectrum 48K, matching Fuse's own default,
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** and a 128K-only release loaded on a 48K machine does what it would do on
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** real hardware: it loads and then dies, usually on a garbled screen with
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** no way out. Standalone Fuse remembers the machine the user last picked in
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** its config file, so the same tape "just works" there and the core looks
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** broken by comparison - see libretro/fuse-libretro#157, reported against
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** the 128K release of Army Moves.
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**
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** Nothing here changes which machine is selected unless the user asks for
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** it with fuse_auto_machine; by default the detection only produces a
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** notification saying which option to change.
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*/
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/* Walk a TZX looking for the two things that only make sense on a
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128K-family machine:
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0x2A "stop the tape if in 48K mode" - the loader itself says so;
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0x33 hardware information, either flagging that the tape does not run
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on a 16K/48K machine at all, or that it uses hardware specific to
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a 128K/+2/+3.
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Every block is bounds-checked before it is stepped over, so a truncated
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or malformed tape ends the walk instead of running off the buffer. This
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only reads; identifying and loading the content is still libspectrum's
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job. */
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static int tzx_needs_128k(const unsigned char *p, size_t size)
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{
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static const unsigned char tzx_sig[8] = {
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'Z', 'X', 'T', 'a', 'p', 'e', '!', 0x1a
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};
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/* Signature (8) + major/minor revision (2). */
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size_t pos = 10;
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if (!p || size < pos || memcmp(p, tzx_sig, sizeof(tzx_sig)) != 0)
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return 0;
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/* Bytes still available from the current read cursor. AVAIL is evaluated
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against pos, which has already stepped past the ID byte. */
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#define AVAIL (size - pos)
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#define NEED(n) do { if (AVAIL < (size_t)(n)) return 0; } while (0)
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#define RD8(o) ((size_t)p[pos + (o)])
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#define RD16(o) (RD8(o) | (RD8((o) + 1) << 8))
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#define RD24(o) (RD16(o) | (RD8((o) + 2) << 16))
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#define RD32(o) (RD24(o) | (RD8((o) + 3) << 24))
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while (pos < size)
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{
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unsigned char id = p[pos];
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size_t len;
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pos++;
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switch (id)
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{
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case 0x10: NEED(4); len = 4 + RD16(2); break; /* std speed */
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case 0x11: NEED(18); len = 18 + RD24(15); break; /* turbo */
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case 0x12: len = 4; break; /* pure tone */
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case 0x13: NEED(1); len = 1 + 2 * RD8(0); break; /* pulse seq */
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case 0x14: NEED(10); len = 10 + RD24(7); break; /* pure data */
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case 0x15: NEED(8); len = 8 + RD24(5); break; /* direct rec */
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case 0x18: NEED(4); len = 4 + RD32(0); break; /* CSW */
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case 0x19: NEED(4); len = 4 + RD32(0); break; /* generalised*/
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case 0x20: len = 2; break; /* pause */
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case 0x21: NEED(1); len = 1 + RD8(0); break; /* group start*/
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case 0x22: len = 0; break; /* group end */
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case 0x23: len = 2; break; /* jump */
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case 0x24: len = 2; break; /* loop start */
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case 0x25: len = 0; break; /* loop end */
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case 0x26: NEED(2); len = 2 + 2 * RD16(0); break; /* call seq */
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case 0x27: len = 0; break; /* return */
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case 0x28: NEED(2); len = 2 + RD16(0); break; /* select */
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case 0x2B: NEED(4); len = 4 + RD32(0); break; /* signal lvl */
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case 0x30: NEED(1); len = 1 + RD8(0); break; /* text */
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case 0x31: NEED(2); len = 2 + RD8(1); break; /* message */
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case 0x32: NEED(2); len = 2 + RD16(0); break; /* archive */
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case 0x33: NEED(1); len = 1 + 3 * RD8(0); break; /* hardware */
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case 0x35: NEED(20); len = 20 + RD32(16); break; /* custom */
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case 0x5a: len = 9; break; /* glue */
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case 0x2a: /* stop the tape if in 48K mode */
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return 1;
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default:
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/* The format reserves a DWORD length on unknown block IDs so a
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reader can skip what it does not know. Trust it that far and
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no further: anything that does not fit ends the walk. */
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NEED(4);
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len = 4 + RD32(0);
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break;
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}
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NEED(len);
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if (id == 0x33)
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{
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size_t count = RD8(0);
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size_t i;
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for (i = 0; i < count; i++)
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{
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size_t type = RD8(1 + 3 * i);
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size_t hw_id = RD8(2 + 3 * i);
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size_t value = RD8(3 + 3 * i);
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/* Only the computer-type entries say anything about the machine. */
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if (type != 0)
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continue;
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/* 0 = 16K, 1 = 48K, 2 = 48K issue 1; value 3 = does not run. */
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if (hw_id <= 2 && value == 3)
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return 1;
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/* 3 = 128K, 4 = +2, 5 = +2A/+3; value 1 = uses its hardware. */
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if (hw_id >= 3 && hw_id <= 5 && value == 1)
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return 1;
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}
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}
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pos += len;
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}
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return 0;
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#undef AVAIL
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#undef NEED
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#undef RD8
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#undef RD16
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#undef RD24
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#undef RD32
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}
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/* The usual ZX Spectrum naming conventions tag the 128K release in the
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filename: "Army Moves - 128k.tzx", "Match Day II (1987)(Ocean)(128k).tzx".
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Only a standalone 128 counts, so a name that merely happens to contain the
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digits ("Bruce Lee - 1280 bytes free") does not match. Directories are
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skipped - a tape does not become a 128K release by living in a folder
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called "128K Games". */
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static int name_says_128k(const char *path)
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{
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const char *name;
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const char *p;
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if (!path)
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return 0;
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name = path;
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for (p = path; *p; p++)
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{
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if (*p == '/' || *p == '\\')
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name = p + 1;
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}
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for (p = name; (p = strstr(p, "128")) != NULL; p += 3)
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{
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char before = (p == name) ? 0 : p[-1];
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char after = p[3];
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if (before >= '0' && before <= '9')
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continue;
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if (after >= '0' && after <= '9')
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continue;
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return 1;
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}
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return 0;
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}
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/* Runs before fuse_init(), so libspectrum's identify is not available yet -
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hence the signature sniff and the extension list rather than a class
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check. Snapshots are deliberately not considered: those carry their own
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machine and Fuse switches to it by itself. */
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static int content_wants_128k(const char *path, const void *data, size_t size)
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{
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static const char *const tape_exts[] = {
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".tzx", ".tap", ".pzx", NULL
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};
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const char *dot;
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size_t i;
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if (tzx_needs_128k((const unsigned char*)data, size))
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return 1;
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if (!path)
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return 0;
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dot = strrchr(path, '.');
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if (!dot)
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return 0;
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for (i = 0; tape_exts[i]; i++)
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{
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const char *a = dot;
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const char *b = tape_exts[i];
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while (*b && *a)
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{
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char c = *a;
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if (c >= 'A' && c <= 'Z')
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c += 'a' - 'A';
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if (c != *b)
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break;
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a++;
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b++;
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}
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if (*b == 0 && *a == 0)
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return name_says_128k(path);
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}
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return 0;
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}
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#ifndef GIT_VERSION
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extern const char* fuse_gitstamp;
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#endif
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@@ -1905,8 +2152,44 @@ bool retro_load_game(const struct retro_game_info *info)
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if (ext_f != NULL && strcmp(ext_f, ".dck") == 0)
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{
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forced_machine_at_init = 1;
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/* LIBSPECTRUM_MACHINE_TS2068 position in machine_list */
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forced_machine_idx = 10;
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forced_machine_idx = MACHINE_IDX_TS2068;
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}
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}
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/* 128K content on a 48K-class model: either switch to a 128K if the user
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has asked us to, or say what to change. Has to happen before
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fuse_init(), which is where settings_init() -> update_variables(1)
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turns the Model option into settings_current.start_machine. */
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if (info && info->size != 0 && !forced_machine_at_init)
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{
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int selected = coreopt(env_cb, core_vars, "fuse_machine", NULL);
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selected += selected < 0;
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if (machine_idx_is_48k_class(selected) &&
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content_wants_128k(info->path, info->data, info->size))
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{
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int auto_machine = coreopt(env_cb, core_vars, "fuse_auto_machine", NULL);
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/* coreopt() indexes into the core_vars value list, which reads
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"disabled|enabled" - same convention as fuse_issue2 and friends.
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An unreadable option (-1) leaves the default in place. */
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if (auto_machine == 1)
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{
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forced_machine_at_init = 1;
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forced_machine_idx = MACHINE_IDX_128;
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log_cb(RETRO_LOG_INFO,
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"128K content detected, selecting Spectrum 128K\n");
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Retro_Msg("128K content: using Spectrum 128K");
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}
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else
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{
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log_cb(RETRO_LOG_WARN,
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"This looks like 128K content, but Model is a 48K machine; "
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"it may fail to load\n");
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Retro_Msg("Looks like 128K content - set Model to Spectrum 128K and reload");
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}
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}
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}
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@@ -2004,7 +2287,7 @@ bool retro_load_game(const struct retro_game_info *info)
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libspectrum_id_t type;
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libspectrum_class_t class;
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if (forced_machine_at_init && forced_machine_idx == 10) /* LIBSPECTRUM_MACHINE_TS2068 position in machine_list */
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if (forced_machine_at_init && forced_machine_idx == MACHINE_IDX_TS2068)
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{
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type = LIBSPECTRUM_ID_CARTRIDGE_DCK;
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class = LIBSPECTRUM_CLASS_CARTRIDGE_TIMEX;
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