Add support for reading SAP (Systeme d'Archivage Pukall) disk images to Thomson systems

hash/to_flop.xml

@@ -5,9 +5,8 @@ license:CC0-1.0
 
 Thanks to DCMOTO (http://dcmoto.free.fr) for info!
 
-FIXME: Many of these images should be 5.25" rather than 3.5". (The old custom Thomson floppy emulation didn't care about form factor.)
-TODO: SAP format is not currently supported.
-TBD: Which images are compatible with which systems?
+FIXME: Some images should be 5.25" rather than 3.5", though TO8/TO9/TO9+ software can assumed to be the latter.
+       (The old custom Thomson floppy emulation didn't care about form factor, and many images are probably conversions.)
 -->
 <softwarelist name="to_flop" description="Thomson TO-series floppy disks">
 

scripts/src/formats.lua

@@ -1771,6 +1771,18 @@ if opt_tool(FORMATS, "RX50_DSK") then
 	}
 end
 
+--------------------------------------------------
+--
+--@src/lib/formats/sap_dsk.h,FORMATS["SAP_DSK"] = true
+--------------------------------------------------
+
+if opt_tool(FORMATS, "SAP_DSK") then
+	files {
+		MAME_DIR.. "src/lib/formats/sap_dsk.cpp",
+		MAME_DIR.. "src/lib/formats/sap_dsk.h",
+	}
+end
+
 --------------------------------------------------
 --
 --@src/lib/formats/sc3000_bit.h,FORMATS["SC3000_BIT"] = true

src/devices/bus/thomson/cd90_015.cpp

@@ -8,6 +8,7 @@
 
 #include "emu.h"
 #include "cd90_015.h"
+#include "formats/sap_dsk.h"
 #include "formats/thom_dsk.h"
 
 DEFINE_DEVICE_TYPE(CD90_015, cd90_015_device, "cd90_015", "Thomson CD 90-015 floppy drive controller")
@@ -78,6 +79,7 @@ void cd90_015_device::floppy_drives(device_slot_interface &device)
 void cd90_015_device::floppy_formats(format_registration &fr)
 {
 	fr.add(FLOPPY_THOMSON_525_FORMAT);
+	fr.add(FLOPPY_SAP_FORMAT);
 }
 
 void cd90_015_device::device_add_mconfig(machine_config &config)

src/devices/bus/thomson/cd90_351.cpp

@@ -10,6 +10,7 @@
 
 #include "emu.h"
 #include "cd90_351.h"
+#include "formats/sap_dsk.h"
 #include "formats/thom_dsk.h"
 #include "machine/thmfc1.h"
 
@@ -60,6 +61,7 @@ void cd90_351_device::floppy_formats(format_registration &fr)
 {
 	fr.add_pc_formats();
 	fr.add(FLOPPY_THOMSON_35_FORMAT);
+	fr.add(FLOPPY_SAP_FORMAT);
 }
 
 void cd90_351_device::device_add_mconfig(machine_config &config)

src/devices/bus/thomson/cd90_640.cpp

@@ -7,6 +7,7 @@
 
 #include "emu.h"
 #include "cd90_640.h"
+#include "formats/sap_dsk.h"
 #include "formats/thom_dsk.h"
 
 DEFINE_DEVICE_TYPE(CD90_640, cd90_640_device, "cd90_640", "Thomson CD 90-640 floppy drive controller")
@@ -49,6 +50,7 @@ void cd90_640_device::floppy_drives(device_slot_interface &device)
 void cd90_640_device::floppy_formats(format_registration &fr)
 {
 	fr.add(FLOPPY_THOMSON_525_FORMAT);
+	fr.add(FLOPPY_SAP_FORMAT);
 }
 
 void cd90_640_device::device_add_mconfig(machine_config &config)

src/lib/formats/all.cpp

@@ -576,6 +576,10 @@
 #include "rx50_dsk.h"
 #endif
 
+#ifdef HAS_FORMATS_SAP_DSK
+#include "sap_dsk.h"
+#endif
+
 #ifdef HAS_FORMATS_SC3000_BIT
 #include "sc3000_bit.h"
 #endif
@@ -1339,6 +1343,9 @@ void mame_formats_full_list(mame_formats_enumerator &en)
 	en.add(FLOPPY_THOMSON_525_FORMAT); // thom_dsk.h
 	en.add(FLOPPY_THOMSON_35_FORMAT); // thom_dsk.h
 #endif
+#ifdef HAS_FORMATS_SAP_DSK
+	en.add(FLOPPY_SAP_FORMAT);
+#endif
 
 	en.category("Texas Instruments");
 #ifdef HAS_FORMATS_TI99_DSK

src/lib/formats/sap_dsk.cpp

@@ -0,0 +1,168 @@
+// license:BSD-3-Clause
+// copyright-holders:AJR
+
+#include "sap_dsk.h"
+
+#include "ioprocs.h"
+#include "multibyte.h"
+
+static constexpr unsigned HEADER_LENGTH = 66;
+static constexpr uint8_t MAGIC_XOR = 0xb3;
+
+const sap_dsk_format FLOPPY_SAP_FORMAT;
+
+inline uint16_t sap_dsk_format::accumulate_crc(uint16_t crc, uint8_t data) noexcept
+{
+	// Almost CRC16-CCITT, but not quite...
+	for (int shift : {0, 4})
+		crc = ((crc >> 4) & 0xfff) ^ 0x1081 * ((crc ^ (data >> shift)) & 0xf);
+	return crc;
+}
+
+const char *sap_dsk_format::name() const noexcept
+{
+	return "sap_dsk";
+}
+
+const char *sap_dsk_format::description() const noexcept
+{
+	return "Thomson SAP disk image (Systeme d'Archivage Pukall)";
+}
+
+const char *sap_dsk_format::extensions() const noexcept
+{
+	return "sap";
+}
+
+bool sap_dsk_format::supports_save() const noexcept
+{
+	return false;
+}
+
+int sap_dsk_format::identify(util::random_read &io, uint32_t form_factor, const std::vector<uint32_t> &variants) const
+{
+	uint8_t buffer[HEADER_LENGTH];
+	auto [err, actual] = read_at(io, 0, buffer, HEADER_LENGTH);
+	if (err || actual != HEADER_LENGTH)
+		return 0;
+
+	// Check ID string
+	if (memcmp(&buffer[1], "SYSTEME D'ARCHIVAGE PUKALL S.A.P. (c) Alexandre PUKALL Avril 1998", HEADER_LENGTH - 1) != 0)
+		return 0;
+
+	// Check disk format
+	if (form_factor == floppy_image::FF_35)
+	{
+		// 3.5" disks must have 80 double-density tracks
+		if ((buffer[0] & 0x7f) != 0x01)
+			return 0;
+	}
+	else if (form_factor == floppy_image::FF_525)
+	{
+		// 5.25" disks must have 40 tracks
+		if ((buffer[0] & 0x7e) != 0x02)
+			return 0;
+	}
+	else if (form_factor != floppy_image::FF_UNKNOWN)
+		return 0;
+
+	uint32_t expected_size = HEADER_LENGTH + uint32_t((buffer[0] & 0x01) ? 256 + 6 : 128 + 6) * ((buffer[0] & 0x02) ? 40 : 80) * 16 * ((buffer[0] & 0x80) ? 2 : 1);
+	uint64_t actual_size;
+	if (!io.length(actual_size) && expected_size == actual_size)
+		return FIFID_SIGN | FIFID_SIZE;
+	else
+		return FIFID_SIGN;
+}
+
+bool sap_dsk_format::load(util::random_read &io, uint32_t form_factor, const std::vector<uint32_t> &variants, floppy_image &image) const
+{
+	uint8_t disk_type;
+	if (auto [err, actual] = read_at(io, 0, &disk_type, 1); err || actual != 1)
+		return false;
+
+	int track_count = (disk_type & 0x02) ? 40 : 80;
+	int head_count = (disk_type & 0x80) ? 2 : 1;
+	int max_tracks, max_heads;
+	image.get_maximal_geometry(max_tracks, max_heads);
+	if (max_heads < head_count || max_tracks < track_count)
+		return false;
+
+	switch (disk_type & 0x03)
+	{
+	case 0x01:
+		image.set_form_variant(floppy_image::FF_35, (disk_type & 0x80) ? floppy_image::DSDD : floppy_image::SSDD);
+		break;
+
+	case 0x02:
+		image.set_form_variant(floppy_image::FF_525, (disk_type & 0x80) ? floppy_image::DSSD : floppy_image::SSSD);
+		break;
+
+	case 0x03:
+		image.set_form_variant(floppy_image::FF_525, (disk_type & 0x80) ? floppy_image::DSDD : floppy_image::SSDD);
+		break;
+
+	default:
+		return false;
+	}
+
+	uint8_t sector_buf[16 * 1024];
+	uint8_t sector_header[4];
+	uint8_t sector_crc[2];
+	desc_pc_sector sectors[16];
+
+	size_t read_offset = HEADER_LENGTH;
+	for (int head = 0; head < head_count; head++)
+	{
+		for (int track = 0; track < track_count; track++)
+		{
+			uint8_t *bufptr = &sector_buf[0];
+			uint8_t track_size = 16;
+			int sector_count = 0;
+			bool is_mfm = disk_type & 0x01;
+			while (track_size != 0)
+			{
+				if (auto [err, actual] = read_at(io, read_offset, &sector_header[0], 4); err || actual != 4)
+					return false;
+				if (sector_count == 0 && sector_header[0] == 1)
+					is_mfm = false;
+				uint8_t sector_size = (sector_header[0] & 2) ? 4 >> (sector_header[0] & 1) : 1;
+				if (track_size < sector_size)
+					return false;
+				uint16_t sector_octets = sector_size * (is_mfm ? 256 : 128);
+				if (auto [err, actual] = read_at(io, read_offset + 4, bufptr, sector_octets); err || actual != sector_octets)
+					return false;
+				if (auto [err, actual] = read_at(io, read_offset + 4 + sector_octets, &sector_crc[0], 2); err || actual != 2)
+					return false;
+
+				uint16_t crc = 0xffff;
+				for (uint8_t data : sector_header)
+					crc = accumulate_crc(crc, data);
+				for (uint16_t i = 0; i < sector_octets; i++)
+				{
+					bufptr[i] ^= MAGIC_XOR;
+					crc = accumulate_crc(crc, bufptr[i]);
+				}
+
+				sectors[sector_count].track = sector_header[2];
+				sectors[sector_count].head = head;
+				sectors[sector_count].sector = sector_header[3];
+				sectors[sector_count].size = sector_size;
+				sectors[sector_count].actual_size = sector_octets;
+				sectors[sector_count].data = bufptr;
+				sectors[sector_count].deleted = false;
+				sectors[sector_count].bad_crc = crc != get_u16be(sector_crc);
+
+				read_offset += sector_octets + 6;
+				bufptr += sector_octets;
+				track_size -= sector_size;
+				sector_count++;
+			}
+			if (is_mfm)
+				build_pc_track_mfm(track, head, image, 100000, sector_count, sectors, calc_default_pc_gap3_size(form_factor, sectors[0].actual_size));
+			else
+				build_pc_track_fm(track, head, image, 100000 / 2, sector_count, sectors, calc_default_pc_gap3_size(form_factor, sectors[0].actual_size));
+		}
+	}
+
+	return true;
+}

src/lib/formats/sap_dsk.h

@@ -0,0 +1,30 @@
+// license:BSD-3-Clause
+// copyright-holders:AJR
+
+#ifndef MAME_FORMATS_SAP_DSK_H
+#define MAME_FORMATS_SAP_DSK_H
+
+#pragma once
+
+#include "flopimg.h"
+
+class sap_dsk_format : public floppy_image_format_t
+{
+public:
+	sap_dsk_format() = default;
+
+	virtual const char *name() const noexcept override;
+	virtual const char *description() const noexcept override;
+	virtual const char *extensions() const noexcept override;
+	virtual bool supports_save() const noexcept override;
+
+	virtual int identify(util::random_read &io, uint32_t form_factor, const std::vector<uint32_t> &variants) const override;
+	virtual bool load(util::random_read &io, uint32_t form_factor, const std::vector<uint32_t> &variants, floppy_image &image) const override;
+
+private:
+	static inline uint16_t accumulate_crc(uint16_t crc, uint8_t data) noexcept;
+};
+
+extern const sap_dsk_format FLOPPY_SAP_FORMAT;
+
+#endif // MAME_FORMATS_SAP_DSK_H

src/mame/thomson/thomson.cpp

@@ -97,6 +97,7 @@
 #include "softlist_dev.h"
 #include "speaker.h"
 
+#include "formats/sap_dsk.h"
 #include "formats/thom_cas.h"
 #include "formats/thom_dsk.h"
 
@@ -494,6 +495,7 @@ static void to35_floppy_formats(format_registration &fr)
 {
 	fr.add_pc_formats();
 	fr.add(FLOPPY_THOMSON_35_FORMAT);
+	fr.add(FLOPPY_SAP_FORMAT);
 }
 
 /* ------------ driver ------------ */