trunk/src/mess/machine/nextmo.c
| r243799 | r243800 | |
|---|
| 182 | 182 | logerror("nextmo: r10_w %d, %02x (%08x)\n", offset, data, space.device().safe_pc()); |
| 183 | 183 | } |
| 184 | 184 | |
| 185 | | void nextmo_device::check_ecc() |
| 185 | /* Reed-Solomon(36,32) in GF(2**8), generator polynomial (x-1)*(x-2)*(x-4)*(x-8) |
| 186 | GF's polynom is the usual 11d |
| 187 | */ |
| 188 | |
| 189 | /* Partial remainders, e.g. t_rem[i] = (i*x^4) % ((x-1)*(x-2)*(x-4)*(x-8)) */ |
| 190 | const UINT32 nextmo_device::t_rem[256] = { |
| 191 | 0x00000000, 0x0f367840, 0x1e6cf080, 0x115a88c0, 0x3cd8fd1d, 0x33ee855d, 0x22b40d9d, 0x2d8275dd, |
| 192 | 0x78ade73a, 0x779b9f7a, 0x66c117ba, 0x69f76ffa, 0x44751a27, 0x4b436267, 0x5a19eaa7, 0x552f92e7, |
| 193 | 0xf047d374, 0xff71ab34, 0xee2b23f4, 0xe11d5bb4, 0xcc9f2e69, 0xc3a95629, 0xd2f3dee9, 0xddc5a6a9, |
| 194 | 0x88ea344e, 0x87dc4c0e, 0x9686c4ce, 0x99b0bc8e, 0xb432c953, 0xbb04b113, 0xaa5e39d3, 0xa5684193, |
| 195 | 0xfd8ebbe8, 0xf2b8c3a8, 0xe3e24b68, 0xecd43328, 0xc15646f5, 0xce603eb5, 0xdf3ab675, 0xd00cce35, |
| 196 | 0x85235cd2, 0x8a152492, 0x9b4fac52, 0x9479d412, 0xb9fba1cf, 0xb6cdd98f, 0xa797514f, 0xa8a1290f, |
| 197 | 0x0dc9689c, 0x02ff10dc, 0x13a5981c, 0x1c93e05c, 0x31119581, 0x3e27edc1, 0x2f7d6501, 0x204b1d41, |
| 198 | 0x75648fa6, 0x7a52f7e6, 0x6b087f26, 0x643e0766, 0x49bc72bb, 0x468a0afb, 0x57d0823b, 0x58e6fa7b, |
| 199 | 0xe7016bcd, 0xe837138d, 0xf96d9b4d, 0xf65be30d, 0xdbd996d0, 0xd4efee90, 0xc5b56650, 0xca831e10, |
| 200 | 0x9fac8cf7, 0x909af4b7, 0x81c07c77, 0x8ef60437, 0xa37471ea, 0xac4209aa, 0xbd18816a, 0xb22ef92a, |
| 201 | 0x1746b8b9, 0x1870c0f9, 0x092a4839, 0x061c3079, 0x2b9e45a4, 0x24a83de4, 0x35f2b524, 0x3ac4cd64, |
| 202 | 0x6feb5f83, 0x60dd27c3, 0x7187af03, 0x7eb1d743, 0x5333a29e, 0x5c05dade, 0x4d5f521e, 0x42692a5e, |
| 203 | 0x1a8fd025, 0x15b9a865, 0x04e320a5, 0x0bd558e5, 0x26572d38, 0x29615578, 0x383bddb8, 0x370da5f8, |
| 204 | 0x6222371f, 0x6d144f5f, 0x7c4ec79f, 0x7378bfdf, 0x5efaca02, 0x51ccb242, 0x40963a82, 0x4fa042c2, |
| 205 | 0xeac80351, 0xe5fe7b11, 0xf4a4f3d1, 0xfb928b91, 0xd610fe4c, 0xd926860c, 0xc87c0ecc, 0xc74a768c, |
| 206 | 0x9265e46b, 0x9d539c2b, 0x8c0914eb, 0x833f6cab, 0xaebd1976, 0xa18b6136, 0xb0d1e9f6, 0xbfe791b6, |
| 207 | 0xd302d687, 0xdc34aec7, 0xcd6e2607, 0xc2585e47, 0xefda2b9a, 0xe0ec53da, 0xf1b6db1a, 0xfe80a35a, |
| 208 | 0xabaf31bd, 0xa49949fd, 0xb5c3c13d, 0xbaf5b97d, 0x9777cca0, 0x9841b4e0, 0x891b3c20, 0x862d4460, |
| 209 | 0x234505f3, 0x2c737db3, 0x3d29f573, 0x321f8d33, 0x1f9df8ee, 0x10ab80ae, 0x01f1086e, 0x0ec7702e, |
| 210 | 0x5be8e2c9, 0x54de9a89, 0x45841249, 0x4ab26a09, 0x67301fd4, 0x68066794, 0x795cef54, 0x766a9714, |
| 211 | 0x2e8c6d6f, 0x21ba152f, 0x30e09def, 0x3fd6e5af, 0x12549072, 0x1d62e832, 0x0c3860f2, 0x030e18b2, |
| 212 | 0x56218a55, 0x5917f215, 0x484d7ad5, 0x477b0295, 0x6af97748, 0x65cf0f08, 0x749587c8, 0x7ba3ff88, |
| 213 | 0xdecbbe1b, 0xd1fdc65b, 0xc0a74e9b, 0xcf9136db, 0xe2134306, 0xed253b46, 0xfc7fb386, 0xf349cbc6, |
| 214 | 0xa6665921, 0xa9502161, 0xb80aa9a1, 0xb73cd1e1, 0x9abea43c, 0x9588dc7c, 0x84d254bc, 0x8be42cfc, |
| 215 | 0x3403bd4a, 0x3b35c50a, 0x2a6f4dca, 0x2559358a, 0x08db4057, 0x07ed3817, 0x16b7b0d7, 0x1981c897, |
| 216 | 0x4cae5a70, 0x43982230, 0x52c2aaf0, 0x5df4d2b0, 0x7076a76d, 0x7f40df2d, 0x6e1a57ed, 0x612c2fad, |
| 217 | 0xc4446e3e, 0xcb72167e, 0xda289ebe, 0xd51ee6fe, 0xf89c9323, 0xf7aaeb63, 0xe6f063a3, 0xe9c61be3, |
| 218 | 0xbce98904, 0xb3dff144, 0xa2857984, 0xadb301c4, 0x80317419, 0x8f070c59, 0x9e5d8499, 0x916bfcd9, |
| 219 | 0xc98d06a2, 0xc6bb7ee2, 0xd7e1f622, 0xd8d78e62, 0xf555fbbf, 0xfa6383ff, 0xeb390b3f, 0xe40f737f, |
| 220 | 0xb120e198, 0xbe1699d8, 0xaf4c1118, 0xa07a6958, 0x8df81c85, 0x82ce64c5, 0x9394ec05, 0x9ca29445, |
| 221 | 0x39cad5d6, 0x36fcad96, 0x27a62556, 0x28905d16, 0x051228cb, 0x0a24508b, 0x1b7ed84b, 0x1448a00b, |
| 222 | 0x416732ec, 0x4e514aac, 0x5f0bc26c, 0x503dba2c, 0x7dbfcff1, 0x7289b7b1, 0x63d33f71, 0x6ce54731, |
| 223 | }; |
| 224 | |
| 225 | const UINT8 nextmo_device::t_exp[768] = { |
| 226 | 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1d, 0x3a, 0x74, 0xe8, 0xcd, 0x87, 0x13, 0x26, |
| 227 | 0x4c, 0x98, 0x2d, 0x5a, 0xb4, 0x75, 0xea, 0xc9, 0x8f, 0x03, 0x06, 0x0c, 0x18, 0x30, 0x60, 0xc0, |
| 228 | 0x9d, 0x27, 0x4e, 0x9c, 0x25, 0x4a, 0x94, 0x35, 0x6a, 0xd4, 0xb5, 0x77, 0xee, 0xc1, 0x9f, 0x23, |
| 229 | 0x46, 0x8c, 0x05, 0x0a, 0x14, 0x28, 0x50, 0xa0, 0x5d, 0xba, 0x69, 0xd2, 0xb9, 0x6f, 0xde, 0xa1, |
| 230 | 0x5f, 0xbe, 0x61, 0xc2, 0x99, 0x2f, 0x5e, 0xbc, 0x65, 0xca, 0x89, 0x0f, 0x1e, 0x3c, 0x78, 0xf0, |
| 231 | 0xfd, 0xe7, 0xd3, 0xbb, 0x6b, 0xd6, 0xb1, 0x7f, 0xfe, 0xe1, 0xdf, 0xa3, 0x5b, 0xb6, 0x71, 0xe2, |
| 232 | 0xd9, 0xaf, 0x43, 0x86, 0x11, 0x22, 0x44, 0x88, 0x0d, 0x1a, 0x34, 0x68, 0xd0, 0xbd, 0x67, 0xce, |
| 233 | 0x81, 0x1f, 0x3e, 0x7c, 0xf8, 0xed, 0xc7, 0x93, 0x3b, 0x76, 0xec, 0xc5, 0x97, 0x33, 0x66, 0xcc, |
| 234 | 0x85, 0x17, 0x2e, 0x5c, 0xb8, 0x6d, 0xda, 0xa9, 0x4f, 0x9e, 0x21, 0x42, 0x84, 0x15, 0x2a, 0x54, |
| 235 | 0xa8, 0x4d, 0x9a, 0x29, 0x52, 0xa4, 0x55, 0xaa, 0x49, 0x92, 0x39, 0x72, 0xe4, 0xd5, 0xb7, 0x73, |
| 236 | 0xe6, 0xd1, 0xbf, 0x63, 0xc6, 0x91, 0x3f, 0x7e, 0xfc, 0xe5, 0xd7, 0xb3, 0x7b, 0xf6, 0xf1, 0xff, |
| 237 | 0xe3, 0xdb, 0xab, 0x4b, 0x96, 0x31, 0x62, 0xc4, 0x95, 0x37, 0x6e, 0xdc, 0xa5, 0x57, 0xae, 0x41, |
| 238 | 0x82, 0x19, 0x32, 0x64, 0xc8, 0x8d, 0x07, 0x0e, 0x1c, 0x38, 0x70, 0xe0, 0xdd, 0xa7, 0x53, 0xa6, |
| 239 | 0x51, 0xa2, 0x59, 0xb2, 0x79, 0xf2, 0xf9, 0xef, 0xc3, 0x9b, 0x2b, 0x56, 0xac, 0x45, 0x8a, 0x09, |
| 240 | 0x12, 0x24, 0x48, 0x90, 0x3d, 0x7a, 0xf4, 0xf5, 0xf7, 0xf3, 0xfb, 0xeb, 0xcb, 0x8b, 0x0b, 0x16, |
| 241 | 0x2c, 0x58, 0xb0, 0x7d, 0xfa, 0xe9, 0xcf, 0x83, 0x1b, 0x36, 0x6c, 0xd8, 0xad, 0x47, 0x8e, 0x01, |
| 242 | 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1d, 0x3a, 0x74, 0xe8, 0xcd, 0x87, 0x13, 0x26, 0x4c, |
| 243 | 0x98, 0x2d, 0x5a, 0xb4, 0x75, 0xea, 0xc9, 0x8f, 0x03, 0x06, 0x0c, 0x18, 0x30, 0x60, 0xc0, 0x9d, |
| 244 | 0x27, 0x4e, 0x9c, 0x25, 0x4a, 0x94, 0x35, 0x6a, 0xd4, 0xb5, 0x77, 0xee, 0xc1, 0x9f, 0x23, 0x46, |
| 245 | 0x8c, 0x05, 0x0a, 0x14, 0x28, 0x50, 0xa0, 0x5d, 0xba, 0x69, 0xd2, 0xb9, 0x6f, 0xde, 0xa1, 0x5f, |
| 246 | 0xbe, 0x61, 0xc2, 0x99, 0x2f, 0x5e, 0xbc, 0x65, 0xca, 0x89, 0x0f, 0x1e, 0x3c, 0x78, 0xf0, 0xfd, |
| 247 | 0xe7, 0xd3, 0xbb, 0x6b, 0xd6, 0xb1, 0x7f, 0xfe, 0xe1, 0xdf, 0xa3, 0x5b, 0xb6, 0x71, 0xe2, 0xd9, |
| 248 | 0xaf, 0x43, 0x86, 0x11, 0x22, 0x44, 0x88, 0x0d, 0x1a, 0x34, 0x68, 0xd0, 0xbd, 0x67, 0xce, 0x81, |
| 249 | 0x1f, 0x3e, 0x7c, 0xf8, 0xed, 0xc7, 0x93, 0x3b, 0x76, 0xec, 0xc5, 0x97, 0x33, 0x66, 0xcc, 0x85, |
| 250 | 0x17, 0x2e, 0x5c, 0xb8, 0x6d, 0xda, 0xa9, 0x4f, 0x9e, 0x21, 0x42, 0x84, 0x15, 0x2a, 0x54, 0xa8, |
| 251 | 0x4d, 0x9a, 0x29, 0x52, 0xa4, 0x55, 0xaa, 0x49, 0x92, 0x39, 0x72, 0xe4, 0xd5, 0xb7, 0x73, 0xe6, |
| 252 | 0xd1, 0xbf, 0x63, 0xc6, 0x91, 0x3f, 0x7e, 0xfc, 0xe5, 0xd7, 0xb3, 0x7b, 0xf6, 0xf1, 0xff, 0xe3, |
| 253 | 0xdb, 0xab, 0x4b, 0x96, 0x31, 0x62, 0xc4, 0x95, 0x37, 0x6e, 0xdc, 0xa5, 0x57, 0xae, 0x41, 0x82, |
| 254 | 0x19, 0x32, 0x64, 0xc8, 0x8d, 0x07, 0x0e, 0x1c, 0x38, 0x70, 0xe0, 0xdd, 0xa7, 0x53, 0xa6, 0x51, |
| 255 | 0xa2, 0x59, 0xb2, 0x79, 0xf2, 0xf9, 0xef, 0xc3, 0x9b, 0x2b, 0x56, 0xac, 0x45, 0x8a, 0x09, 0x12, |
| 256 | 0x24, 0x48, 0x90, 0x3d, 0x7a, 0xf4, 0xf5, 0xf7, 0xf3, 0xfb, 0xeb, 0xcb, 0x8b, 0x0b, 0x16, 0x2c, |
| 257 | 0x58, 0xb0, 0x7d, 0xfa, 0xe9, 0xcf, 0x83, 0x1b, 0x36, 0x6c, 0xd8, 0xad, 0x47, 0x8e, 0x01, 0x02, |
| 258 | 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1d, 0x3a, 0x74, 0xe8, 0xcd, 0x87, 0x13, 0x26, 0x4c, 0x98, |
| 259 | 0x2d, 0x5a, 0xb4, 0x75, 0xea, 0xc9, 0x8f, 0x03, 0x06, 0x0c, 0x18, 0x30, 0x60, 0xc0, 0x9d, 0x27, |
| 260 | 0x4e, 0x9c, 0x25, 0x4a, 0x94, 0x35, 0x6a, 0xd4, 0xb5, 0x77, 0xee, 0xc1, 0x9f, 0x23, 0x46, 0x8c, |
| 261 | 0x05, 0x0a, 0x14, 0x28, 0x50, 0xa0, 0x5d, 0xba, 0x69, 0xd2, 0xb9, 0x6f, 0xde, 0xa1, 0x5f, 0xbe, |
| 262 | 0x61, 0xc2, 0x99, 0x2f, 0x5e, 0xbc, 0x65, 0xca, 0x89, 0x0f, 0x1e, 0x3c, 0x78, 0xf0, 0xfd, 0xe7, |
| 263 | 0xd3, 0xbb, 0x6b, 0xd6, 0xb1, 0x7f, 0xfe, 0xe1, 0xdf, 0xa3, 0x5b, 0xb6, 0x71, 0xe2, 0xd9, 0xaf, |
| 264 | 0x43, 0x86, 0x11, 0x22, 0x44, 0x88, 0x0d, 0x1a, 0x34, 0x68, 0xd0, 0xbd, 0x67, 0xce, 0x81, 0x1f, |
| 265 | 0x3e, 0x7c, 0xf8, 0xed, 0xc7, 0x93, 0x3b, 0x76, 0xec, 0xc5, 0x97, 0x33, 0x66, 0xcc, 0x85, 0x17, |
| 266 | 0x2e, 0x5c, 0xb8, 0x6d, 0xda, 0xa9, 0x4f, 0x9e, 0x21, 0x42, 0x84, 0x15, 0x2a, 0x54, 0xa8, 0x4d, |
| 267 | 0x9a, 0x29, 0x52, 0xa4, 0x55, 0xaa, 0x49, 0x92, 0x39, 0x72, 0xe4, 0xd5, 0xb7, 0x73, 0xe6, 0xd1, |
| 268 | 0xbf, 0x63, 0xc6, 0x91, 0x3f, 0x7e, 0xfc, 0xe5, 0xd7, 0xb3, 0x7b, 0xf6, 0xf1, 0xff, 0xe3, 0xdb, |
| 269 | 0xab, 0x4b, 0x96, 0x31, 0x62, 0xc4, 0x95, 0x37, 0x6e, 0xdc, 0xa5, 0x57, 0xae, 0x41, 0x82, 0x19, |
| 270 | 0x32, 0x64, 0xc8, 0x8d, 0x07, 0x0e, 0x1c, 0x38, 0x70, 0xe0, 0xdd, 0xa7, 0x53, 0xa6, 0x51, 0xa2, |
| 271 | 0x59, 0xb2, 0x79, 0xf2, 0xf9, 0xef, 0xc3, 0x9b, 0x2b, 0x56, 0xac, 0x45, 0x8a, 0x09, 0x12, 0x24, |
| 272 | 0x48, 0x90, 0x3d, 0x7a, 0xf4, 0xf5, 0xf7, 0xf3, 0xfb, 0xeb, 0xcb, 0x8b, 0x0b, 0x16, 0x2c, 0x58, |
| 273 | 0xb0, 0x7d, 0xfa, 0xe9, 0xcf, 0x83, 0x1b, 0x36, 0x6c, 0xd8, 0xad, 0x47, 0x8e, 0x01, 0x02, 0x04, |
| 274 | }; |
| 275 | |
| 276 | const UINT8 nextmo_device::t_log[256] = { |
| 277 | 0x00, 0x00, 0x01, 0x19, 0x02, 0x32, 0x1a, 0xc6, 0x03, 0xdf, 0x33, 0xee, 0x1b, 0x68, 0xc7, 0x4b, |
| 278 | 0x04, 0x64, 0xe0, 0x0e, 0x34, 0x8d, 0xef, 0x81, 0x1c, 0xc1, 0x69, 0xf8, 0xc8, 0x08, 0x4c, 0x71, |
| 279 | 0x05, 0x8a, 0x65, 0x2f, 0xe1, 0x24, 0x0f, 0x21, 0x35, 0x93, 0x8e, 0xda, 0xf0, 0x12, 0x82, 0x45, |
| 280 | 0x1d, 0xb5, 0xc2, 0x7d, 0x6a, 0x27, 0xf9, 0xb9, 0xc9, 0x9a, 0x09, 0x78, 0x4d, 0xe4, 0x72, 0xa6, |
| 281 | 0x06, 0xbf, 0x8b, 0x62, 0x66, 0xdd, 0x30, 0xfd, 0xe2, 0x98, 0x25, 0xb3, 0x10, 0x91, 0x22, 0x88, |
| 282 | 0x36, 0xd0, 0x94, 0xce, 0x8f, 0x96, 0xdb, 0xbd, 0xf1, 0xd2, 0x13, 0x5c, 0x83, 0x38, 0x46, 0x40, |
| 283 | 0x1e, 0x42, 0xb6, 0xa3, 0xc3, 0x48, 0x7e, 0x6e, 0x6b, 0x3a, 0x28, 0x54, 0xfa, 0x85, 0xba, 0x3d, |
| 284 | 0xca, 0x5e, 0x9b, 0x9f, 0x0a, 0x15, 0x79, 0x2b, 0x4e, 0xd4, 0xe5, 0xac, 0x73, 0xf3, 0xa7, 0x57, |
| 285 | 0x07, 0x70, 0xc0, 0xf7, 0x8c, 0x80, 0x63, 0x0d, 0x67, 0x4a, 0xde, 0xed, 0x31, 0xc5, 0xfe, 0x18, |
| 286 | 0xe3, 0xa5, 0x99, 0x77, 0x26, 0xb8, 0xb4, 0x7c, 0x11, 0x44, 0x92, 0xd9, 0x23, 0x20, 0x89, 0x2e, |
| 287 | 0x37, 0x3f, 0xd1, 0x5b, 0x95, 0xbc, 0xcf, 0xcd, 0x90, 0x87, 0x97, 0xb2, 0xdc, 0xfc, 0xbe, 0x61, |
| 288 | 0xf2, 0x56, 0xd3, 0xab, 0x14, 0x2a, 0x5d, 0x9e, 0x84, 0x3c, 0x39, 0x53, 0x47, 0x6d, 0x41, 0xa2, |
| 289 | 0x1f, 0x2d, 0x43, 0xd8, 0xb7, 0x7b, 0xa4, 0x76, 0xc4, 0x17, 0x49, 0xec, 0x7f, 0x0c, 0x6f, 0xf6, |
| 290 | 0x6c, 0xa1, 0x3b, 0x52, 0x29, 0x9d, 0x55, 0xaa, 0xfb, 0x60, 0x86, 0xb1, 0xbb, 0xcc, 0x3e, 0x5a, |
| 291 | 0xcb, 0x59, 0x5f, 0xb0, 0x9c, 0xa9, 0xa0, 0x51, 0x0b, 0xf5, 0x16, 0xeb, 0x7a, 0x75, 0x2c, 0xd7, |
| 292 | 0x4f, 0xae, 0xd5, 0xe9, 0xe6, 0xe7, 0xad, 0xe8, 0x74, 0xd6, 0xf4, 0xea, 0xa8, 0x50, 0x58, 0xaf, |
| 293 | }; |
| 294 | |
| 295 | UINT32 nextmo_device::ecc_block(const UINT8 *s, int ss) |
| 186 | 296 | { |
| 187 | | logerror("nextmo: check_ecc\n"); |
| 188 | | for(int i=0; i<0x400; i++) |
| 189 | | sector[i] = i; |
| 297 | UINT32 r = (s[0] << 24) | (s[ss] << 16) | (s[2*ss] << 8) | s[3*ss]; |
| 298 | |
| 299 | s += 4*ss; |
| 300 | for(int i=4; i<36; i++) { |
| 301 | r = t_rem[r >> 24] ^ (r << 8); |
| 302 | if(i < 32) { |
| 303 | r ^= *s; |
| 304 | s += ss; |
| 305 | } |
| 306 | } |
| 307 | return r; |
| 190 | 308 | } |
| 191 | 309 | |
| 310 | void nextmo_device::compute_one_ecc(int off, int step) |
| 311 | { |
| 312 | UINT32 ecc = ecc_block(sector+off, step); |
| 313 | sector[off+32*step] = ecc >> 24; |
| 314 | sector[off+33*step] = ecc >> 16; |
| 315 | sector[off+34*step] = ecc >> 8; |
| 316 | sector[off+35*step] = ecc; |
| 317 | } |
| 318 | |
| 192 | 319 | void nextmo_device::compute_ecc() |
| 193 | 320 | { |
| 194 | | logerror("nextmo: compute_ecc\n"); |
| 195 | | memset(sector+0x400, 0, 0x110); |
| 321 | for(int i=31; i>0; i--) |
| 322 | memmove(sector+36*i, sector+32*i, 32); |
| 323 | for(int i=0; i<32; i++) |
| 324 | compute_one_ecc(i, 36); |
| 325 | for(int i=0; i<36; i++) |
| 326 | compute_one_ecc(36*i, 1); |
| 196 | 327 | } |
| 328 | |
| 329 | int nextmo_device::fix_one_ecc(int off, int step) |
| 330 | { |
| 331 | UINT32 ecc = ecc_block(sector+off, step); |
| 332 | UINT32 ref_ecc = |
| 333 | (sector[off+32*step] << 24) | |
| 334 | (sector[off+33*step] << 16) | |
| 335 | (sector[off+34*step] << 8) | |
| 336 | sector[off+35*step]; |
| 337 | if(ref_ecc == ecc) |
| 338 | return 0; |
| 339 | |
| 340 | // Syndrome polynomial |
| 341 | // syn[i] = value of the codebook polynom at 2**(i-1) |
| 342 | UINT8 syn[5]; |
| 343 | memset(syn, 0, 5); |
| 344 | syn[0] = 1; |
| 345 | for(int i=0; i<36; i++) { |
| 346 | UINT8 v = sector[off+step*(35-i)]; |
| 347 | if(v) { |
| 348 | syn[1] ^= v; |
| 349 | int lv = t_log[v]; |
| 350 | syn[2] ^= t_exp[lv+i]; |
| 351 | syn[3] ^= t_exp[lv+2*i]; |
| 352 | syn[4] ^= t_exp[lv+3*i]; |
| 353 | } |
| 354 | } |
| 355 | |
| 356 | // Berlekamp-Massey |
| 357 | |
| 358 | UINT8 sigma[5]; |
| 359 | UINT8 omega[5]; |
| 360 | UINT8 tau[5]; |
| 361 | UINT8 gamma[5]; |
| 362 | int d; |
| 363 | int b; |
| 364 | |
| 365 | memset(sigma, 0, 5); |
| 366 | memset(omega, 0, 5); |
| 367 | memset(tau, 0, 5); |
| 368 | memset(gamma, 0, 5); |
| 369 | sigma[0] = 1; |
| 370 | omega[0] = 1; |
| 371 | tau[0] = 1; |
| 372 | d = 0; |
| 373 | b = 0; |
| 374 | |
| 375 | for(int l=1; l<5; l++) { |
| 376 | // 1- Determine the l-order coefficient syn*sigma |
| 377 | UINT8 delta = 0; |
| 378 | for(int i=0; i<=l; i++) |
| 379 | if(sigma[i] && syn[l-i]) |
| 380 | delta ^= t_exp[t_log[sigma[i]] + t_log[syn[l-i]]]; |
| 381 | |
| 382 | // 2- Select update method a/b |
| 383 | int limit = (l+1)/2; |
| 384 | int exact = l & 1; |
| 385 | if(!delta || d > limit || (d == limit && exact && !b)) { |
| 386 | // 2.1- Method a |
| 387 | // b and d unchanged |
| 388 | // tau and gamma multiplied by x |
| 389 | // sigma = sigma - delta * tau |
| 390 | // omega = omega - delta * gamma |
| 391 | |
| 392 | for(int i=0; i<l; i++) { |
| 393 | tau[l-i] = tau[l-i-1]; |
| 394 | gamma[l-i] = gamma[l-i-1]; |
| 395 | } |
| 396 | tau[0] = gamma[0] = 0; |
| 397 | |
| 398 | if(delta) { |
| 399 | UINT8 ldelta = t_log[delta]; |
| 400 | for(int i=1; i<=l; i++) { |
| 401 | if(tau[i]) |
| 402 | sigma[i] ^= t_exp[t_log[tau [i]] + ldelta]; |
| 403 | if(gamma[i]) |
| 404 | omega[i] ^= t_exp[t_log[gamma[i]] + ldelta]; |
| 405 | } |
| 406 | } |
| 407 | } else { |
| 408 | // 2.2- Method b |
| 409 | d = l-d; |
| 410 | b = !b; |
| 411 | // tau(n+1) = sigma(n) / delta |
| 412 | // gamma(n+1) = omega(n) / delta |
| 413 | // sigma(n+1) = sigma(n) - delta*x*tau(n) |
| 414 | // omega(n+1) = omega(n) - delta*x*gamma(n) |
| 415 | UINT8 ldelta = t_log[delta]; |
| 416 | UINT8 ildelta = ldelta ^ 255; |
| 417 | for(int i=l; i>0; i--) { |
| 418 | if(tau[i-1]) |
| 419 | sigma[i] = sigma[i] ^ t_exp[t_log[tau [i-1]] + ldelta]; |
| 420 | |
| 421 | if(gamma[i-1]) |
| 422 | omega[i] = omega[i] ^ t_exp[t_log[gamma[i-1]] + ldelta]; |
| 423 | |
| 424 | if(sigma[i-1]) |
| 425 | tau[i-1] = t_exp[t_log[sigma[i-1]] + ildelta]; |
| 426 | else |
| 427 | tau[i-1] = 0x00; |
| 428 | |
| 429 | if(omega[i-1]) |
| 430 | gamma[i-1] = t_exp[t_log[omega[i-1]] + ildelta]; |
| 431 | else |
| 432 | gamma[i-1] = 0x00; |
| 433 | } |
| 434 | } |
| 435 | } |
| 436 | |
| 437 | // Find the roots of sigma to get the error positions (they're the inverses of 2**position) |
| 438 | // Compute the error(s) |
| 439 | |
| 440 | if(sigma[3] || sigma[4]) { |
| 441 | // Should not happen |
| 442 | return -1; |
| 443 | } |
| 444 | |
| 445 | if(sigma[2] && sigma[0]) { |
| 446 | int epos1, epos2; |
| 447 | UINT8 ls1 = t_log[sigma[1]]; |
| 448 | UINT8 ls2 = t_log[sigma[2]]; |
| 449 | for(epos1 = 0; epos1 < 256; epos1++) { |
| 450 | UINT8 res = sigma[0]; |
| 451 | if(sigma[1]) |
| 452 | res ^= t_exp[255-epos1+ls1]; |
| 453 | res ^= t_exp[2*(255-epos1)+ls2]; |
| 454 | if(!res) |
| 455 | break; |
| 456 | } |
| 457 | if(epos1 > 35) |
| 458 | return -1; |
| 459 | |
| 460 | // sigma = c.(x-1/r1)(x-1/r2) = c.x*x - c*x*(1/r1+1/r2) + c/(r1*r2) |
| 461 | |
| 462 | // s0 = s2/(r1*r2) -> r1*r2*s0 = s2 -> r1 = s2 / (r1*s0) |
| 463 | // -> r2 = sigma[2]/(r1*sigma[0]) |
| 464 | epos2 = ls2 - epos1 - t_log[sigma[0]]; |
| 465 | if(epos2 < 0) |
| 466 | epos2 += 255; |
| 467 | if(epos2 > 35) |
| 468 | return -1; |
| 469 | |
| 470 | UINT8 err1 = omega[0]; |
| 471 | if(omega[1]) |
| 472 | err1 ^= t_exp[t_log[omega[1]] + 255 - epos1]; |
| 473 | if(omega[2]) |
| 474 | err1 ^= t_exp[t_log[omega[2]] + 2*(255 - epos1)]; |
| 475 | err1 = t_log[err1] + epos1; |
| 476 | UINT8 div = t_log[1 ^ t_exp[255 + epos2 - epos1]]; |
| 477 | err1 = t_exp[255 + err1 - div]; |
| 478 | |
| 479 | UINT8 err2 = omega[0]; |
| 480 | if(omega[1]) |
| 481 | err2 ^= t_exp[t_log[omega[1]] + 255 - epos2]; |
| 482 | if(omega[2]) |
| 483 | err2 ^= t_exp[t_log[omega[2]] + 2*(255 - epos2)]; |
| 484 | err2 = t_log[err2] + epos2; |
| 485 | div = t_log[1 ^ t_exp[255 + epos1 - epos2]]; |
| 486 | err2 = t_exp[255 + err2 - div]; |
| 487 | |
| 488 | sector[off + step*(35-epos1)] ^= err1; |
| 489 | sector[off + step*(35-epos2)] ^= err2; |
| 490 | return 2; |
| 491 | |
| 492 | } else if(sigma[1] && sigma[0]) { |
| 493 | // sigma = c.(x-1/r1) -> r1=sigma[1]/sigma[0] |
| 494 | int epos = t_log[sigma[1]] - t_log[sigma[0]]; |
| 495 | |
| 496 | if(epos > 35) |
| 497 | return -1; |
| 498 | |
| 499 | UINT8 err = sigma[1]^omega[1]; |
| 500 | sector[off + step*(35-epos)] ^= err; |
| 501 | return 1; |
| 502 | |
| 503 | } else { |
| 504 | // Should not happen |
| 505 | return -1; |
| 506 | } |
| 507 | } |
| 508 | |
| 509 | void nextmo_device::check_ecc() |
| 510 | { |
| 511 | int ecount = 0; |
| 512 | bool errors_left, errors_fixed; |
| 513 | do { |
| 514 | errors_left = false; |
| 515 | errors_fixed = false; |
| 516 | for(int i=0; i<32; i++) { |
| 517 | int ec = fix_one_ecc(i, 36); |
| 518 | if(ec == -1) |
| 519 | errors_left = true; |
| 520 | else if(ec) { |
| 521 | ecount += ec; |
| 522 | errors_fixed = true; |
| 523 | } |
| 524 | } |
| 525 | if(!errors_left) |
| 526 | break; |
| 527 | for(int i=0; i<36; i++) { |
| 528 | int ec = fix_one_ecc(36*i, 1); |
| 529 | if(ec == -1) |
| 530 | errors_left = true; |
| 531 | else if(ec) { |
| 532 | ecount += ec; |
| 533 | errors_fixed = true; |
| 534 | } |
| 535 | } |
| 536 | } while(errors_left && errors_fixed); |
| 537 | |
| 538 | if(errors_left) |
| 539 | fprintf(stderr, "Fix failed\n"); |
| 540 | |
| 541 | for(int i=1; i<32; i++) |
| 542 | memmove(sector+i*32, sector+i*36, 32); |
| 543 | } |