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root/cebix/SheepShaver/src/rom_patches.cpp

Comparing SheepShaver/src/rom_patches.cpp (file contents):
Revision 1.1 by cebix, 2002-02-04T16:58:13Z vs.
Revision 1.2 by gbeauche, 2002-04-21T15:07:07Z

#	Line 74 | Line 74 | static bool patch_nanokernel(void);
74		static bool patch_68k(void);
75
76
77	+	// Decode LZSS data
78	+	static void decode_lzss(const uint8 *src, uint8 *dest, int size)
79	+	{
80	+	char dict[0x1000];
81	+	int run_mask = 0, dict_idx = 0xfee;
82	+	for (;;) {
83	+	if (run_mask < 0x100) {
84	+	// Start new run
85	+	if (--size < 0)
86	+	break;
87	+	run_mask = *src++ | 0xff00;
88	+	}
89	+	bool bit = run_mask & 1;
90	+	run_mask >>= 1;
91	+	if (bit) {
92	+	// Verbatim copy
93	+	if (--size < 0)
94	+	break;
95	+	int c = *src++;
96	+	dict[dict_idx++] = c;
97	+	*dest++ = c;
98	+	dict_idx &= 0xfff;
99	+	} else {
100	+	// Copy from dictionary
101	+	if (--size < 0)
102	+	break;
103	+	int idx = *src++;
104	+	if (--size < 0)
105	+	break;
106	+	int cnt = *src++;
107	+	idx |= (cnt << 4) & 0xf00;
108	+	cnt = (cnt & 0x0f) + 3;
109	+	while (cnt--) {
110	+	char c = dict[idx++];
111	+	dict[dict_idx++] = c;
112	+	*dest++ = c;
113	+	idx &= 0xfff;
114	+	dict_idx &= 0xfff;
115	+	}
116	+	}
117	+	}
118	+	}
119	+
120	+	// Decode parcels of ROM image (MacOS 9.X and even earlier)
121	+	void decode_parcels(const uint8 *src, uint8 *dest, int size)
122	+	{
123	+	uint32 parcel_offset = 0x14;
124	+	D(bug("Offset   Type Name\n"));
125	+	while (parcel_offset != 0) {
126	+	const uint32 *parcel_data = (uint32 *)(src + parcel_offset);
127	+	parcel_offset = ntohl(parcel_data[0]);
128	+	uint32 parcel_type = ntohl(parcel_data[1]);
129	+	D(bug("%08x %c%c%c%c %s\n", parcel_offset,
130	+	(parcel_type >> 24) & 0xff, (parcel_type >> 16) & 0xff,
131	+	(parcel_type >> 8) & 0xff, parcel_type & 0xff, &parcel_data[6]));
132	+	if (parcel_type == FOURCC('r','o','m',' ')) {
133	+	uint32 lzss_offset  = ntohl(parcel_data[2]);
134	+	uint32 lzss_size = ((uint32)src + parcel_offset) - ((uint32)parcel_data + lzss_offset);
135	+	decode_lzss((uint8 *)parcel_data + lzss_offset, dest, lzss_size);
136	+	}
137	+	}
138	+	}
139	+
140	+
141	+	/*
142	+	*  Decode ROM image, 4 MB plain images or NewWorld images
143	+	*/
144	+
145	+	bool DecodeROM(uint8 *data, uint32 size)
146	+	{
147	+	if (size == ROM_SIZE) {
148	+	// Plain ROM image
149	+	memcpy((void *)ROM_BASE, data, ROM_SIZE);
150	+	return true;
151	+	}
152	+	else if (strncmp((char *)data, "<CHRP-BOOT>", 11) == 0) {
153	+	// CHRP compressed ROM image
154	+	uint32 image_offset, image_size;
155	+	bool decode_info_ok = false;
156	+
157	+	char *s = strstr((char *)data, "constant lzss-offset");
158	+	if (s != NULL) {
159	+	// Probably a plain LZSS compressed ROM image
160	+	if (sscanf(s - 7, "%06x", &image_offset) == 1) {
161	+	s = strstr((char *)data, "constant lzss-size");
162	+	if (s != NULL && (sscanf(s - 7, "%06x", &image_size) == 1))
163	+	decode_info_ok = true;
164	+	}
165	+	}
166	+	else {
167	+	// Probably a MacOS 9.2.x ROM image
168	+	s = strstr((char *)data, "constant parcels-offset");
169	+	if (s != NULL) {
170	+	if (sscanf(s - 7, "%06x", &image_offset) == 1) {
171	+	s = strstr((char *)data, "constant parcels-size");
172	+	if (s != NULL && (sscanf(s - 7, "%06x", &image_size) == 1))
173	+	decode_info_ok = true;
174	+	}
175	+	}
176	+	}
177	+
178	+	// No valid information to decode the ROM found?
179	+	if (!decode_info_ok)
180	+	return false;
181	+
182	+	// Check signature, this could be a parcels-based ROM image
183	+	uint32 rom_signature = ntohl(*(uint32 *)(data + image_offset));
184	+	if (rom_signature == FOURCC('p','r','c','l')) {
185	+	D(bug("Offset of parcels data: %08x\n", image_offset));
186	+	D(bug("Size of parcels data: %08x\n", image_size));
187	+	decode_parcels(data + image_offset, (uint8 *)ROM_BASE, image_size);
188	+	}
189	+	else {
190	+	D(bug("Offset of compressed data: %08x\n", image_offset));
191	+	D(bug("Size of compressed data: %08x\n", image_size));
192	+	decode_lzss(data + image_offset, (uint8 *)ROM_BASE, image_size);
193	+	}
194	+	return true;
195	+	}
196	+	return false;
197	+	}
198	+
199	+
200		/*
201		*  Search ROM for byte string, return ROM offset (or 0)
202		*/

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