src/wd279x.c

Mon, 06 Dec 2010 08:27:21 +0000

author
Philip Pemberton <philpem@philpem.me.uk>
date
Mon, 06 Dec 2010 08:27:21 +0000
changeset 76
2ef98ea1e944
parent 54
57c6ef81ae81
child 77
e7898cbae0c6
child 78
c149c13aff1c
permissions
-rw-r--r--

move edge-sensitive FDC IRQ to main()

philpem@48 1 #include <stdint.h>
philpem@48 2 #include <stdbool.h>
philpem@49 3 #include <malloc.h>
philpem@53 4 #include "musashi/m68k.h"
philpem@48 5 #include "wd279x.h"
philpem@48 6
philpem@48 7 /// WD2797 command constants
philpem@48 8 enum {
philpem@48 9 CMD_MASK = 0xF0, ///< Bit mask to detect command bits
philpem@48 10 CMD_RESTORE = 0x00, ///< Restore (recalibrate, seek to track 0)
philpem@48 11 CMD_SEEK = 0x10, ///< Seek to given track
philpem@48 12 CMD_STEP = 0x20, ///< Step
philpem@48 13 CMD_STEP_TU = 0x30, ///< Step and update track register
philpem@48 14 CMD_STEPIN = 0x40, ///< Step In
philpem@48 15 CMD_STEPIN_TU = 0x50, ///< Step In and update track register
philpem@48 16 CMD_STEPOUT = 0x60, ///< Step Out
philpem@48 17 CMD_STEPOUT_TU = 0x70, ///< Step Out and update track register
philpem@48 18 CMD_READ_SECTOR = 0x80, ///< Read Sector
philpem@48 19 CMD_READ_SECTOR_MULTI = 0x90, ///< Read Multiple Sectors
philpem@48 20 CMD_WRITE_SECTOR = 0xA0, ///< Write Sector
philpem@48 21 CMD_WRITE_SECTOR_MULTI = 0xB0, ///< Write Multiple Sectors
philpem@48 22 CMD_READ_ADDRESS = 0xC0, ///< Read Address (IDAM contents)
philpem@48 23 CMD_FORCE_INTERRUPT = 0xD0, ///< Force Interrupt
philpem@48 24 CMD_READ_TRACK = 0xE0, ///< Read Track
philpem@48 25 CMD_FORMAT_TRACK = 0xF0 ///< Format Track
philpem@48 26 };
philpem@48 27
philpem@48 28
philpem@49 29 void wd2797_init(WD2797_CTX *ctx)
philpem@48 30 {
philpem@48 31 // track, head and sector unknown
philpem@49 32 ctx->track = ctx->head = ctx->sector = 0;
philpem@48 33
philpem@49 34 // no IRQ pending
philpem@76 35 ctx->irq = false;
philpem@48 36
philpem@48 37 // no data available
philpem@49 38 ctx->data_pos = ctx->data_len = 0;
philpem@49 39 ctx->data = NULL;
philpem@49 40
philpem@76 41 // Status register clear, not busy; type1 command
philpem@49 42 ctx->status = 0;
philpem@76 43 ctx->cmd_has_drq = false;
philpem@49 44
philpem@49 45 // Clear data register
philpem@49 46 ctx->data_reg = 0;
philpem@49 47
philpem@76 48 // Last step direction = "towards zero"
philpem@49 49 ctx->last_step_dir = -1;
philpem@48 50
philpem@48 51 // No disc image loaded
philpem@48 52 ctx->disc_image = NULL;
philpem@49 53 ctx->geom_secsz = ctx->geom_spt = ctx->geom_heads = ctx->geom_tracks = 0;
philpem@48 54 }
philpem@48 55
philpem@48 56
philpem@49 57 void wd2797_reset(WD2797_CTX *ctx)
philpem@49 58 {
philpem@49 59 // track, head and sector unknown
philpem@49 60 ctx->track = ctx->head = ctx->sector = 0;
philpem@49 61
philpem@49 62 // no IRQ pending
philpem@76 63 ctx->irq = false;
philpem@49 64
philpem@49 65 // no data available
philpem@49 66 ctx->data_pos = ctx->data_len = 0;
philpem@49 67
philpem@49 68 // Status register clear, not busy
philpem@49 69 ctx->status = 0;
philpem@49 70
philpem@49 71 // Clear data register
philpem@49 72 ctx->data_reg = 0;
philpem@49 73
philpem@49 74 // Last step direction
philpem@49 75 ctx->last_step_dir = -1;
philpem@49 76 }
philpem@49 77
philpem@49 78
philpem@49 79 void wd2797_done(WD2797_CTX *ctx)
philpem@49 80 {
philpem@49 81 // Reset the WD2797
philpem@49 82 wd2797_reset(ctx);
philpem@49 83
philpem@49 84 // Free any allocated memory
philpem@49 85 if (ctx->data) {
philpem@49 86 free(ctx->data);
philpem@49 87 ctx->data = NULL;
philpem@49 88 }
philpem@49 89 }
philpem@49 90
philpem@49 91
philpem@49 92 bool wd2797_get_irq(WD2797_CTX *ctx)
philpem@48 93 {
philpem@76 94 return ctx->irq;
philpem@48 95 }
philpem@48 96
philpem@48 97
philpem@49 98 bool wd2797_get_drq(WD2797_CTX *ctx)
philpem@48 99 {
philpem@48 100 return (ctx->data_pos < ctx->data_len);
philpem@48 101 }
philpem@48 102
philpem@48 103
philpem@49 104 WD2797_ERR wd2797_load(WD2797_CTX *ctx, FILE *fp, int secsz, int spt, int heads)
philpem@49 105 {
philpem@49 106 size_t filesize;
philpem@49 107
philpem@49 108 // Start by finding out how big the image file is
philpem@49 109 fseek(fp, 0, SEEK_END);
philpem@49 110 filesize = ftell(fp);
philpem@49 111 fseek(fp, 0, SEEK_SET);
philpem@49 112
philpem@49 113 // Now figure out how many tracks it contains
philpem@49 114 int tracks = filesize / secsz / spt / heads;
philpem@49 115 // Confirm...
philpem@49 116 if (tracks < 1) {
philpem@49 117 return WD2797_ERR_BAD_GEOM;
philpem@49 118 }
philpem@49 119
philpem@49 120 // Allocate enough memory to store one disc track
philpem@49 121 if (ctx->data) {
philpem@49 122 free(ctx->data);
philpem@49 123 }
philpem@49 124 ctx->data = malloc(secsz * spt);
philpem@49 125 if (!ctx->data)
philpem@49 126 return WD2797_ERR_NO_MEMORY;
philpem@49 127
philpem@49 128 // Load the image and the geometry data
philpem@49 129 ctx->disc_image = fp;
philpem@49 130 ctx->geom_tracks = tracks;
philpem@49 131 ctx->geom_secsz = secsz;
philpem@49 132 ctx->geom_heads = heads;
philpem@49 133 ctx->geom_spt = spt;
philpem@49 134
philpem@49 135 return WD2797_ERR_OK;
philpem@49 136 }
philpem@49 137
philpem@49 138
philpem@49 139 void wd2797_unload(WD2797_CTX *ctx)
philpem@49 140 {
philpem@49 141 // Free memory buffer
philpem@49 142 if (ctx->data) {
philpem@49 143 free(ctx->data);
philpem@49 144 ctx->data = NULL;
philpem@49 145 }
philpem@49 146
philpem@49 147 // Clear file pointer
philpem@49 148 ctx->disc_image = NULL;
philpem@49 149
philpem@49 150 // Clear the disc geometry
philpem@49 151 ctx->geom_tracks = ctx->geom_secsz = ctx->geom_spt = ctx->geom_heads = 0;
philpem@49 152 }
philpem@49 153
philpem@49 154
philpem@49 155 uint8_t wd2797_read_reg(WD2797_CTX *ctx, uint8_t addr)
philpem@48 156 {
philpem@48 157 uint8_t temp = 0;
philpem@48 158
philpem@48 159 switch (addr & 0x03) {
philpem@49 160 case WD2797_REG_STATUS: // Status register
philpem@48 161 // Read from status register clears IRQ
philpem@76 162 ctx->irq = false;
philpem@48 163
philpem@48 164 // Get current status flags (set by last command)
philpem@48 165 // DRQ bit
philpem@53 166 if (ctx->cmd_has_drq) {
philpem@53 167 printf("\tWDFDC rd sr, has drq, pos=%lu len=%lu\n", ctx->data_pos, ctx->data_len);
philpem@53 168 temp = ctx->status & ~0x03;
philpem@48 169 temp |= (ctx->data_pos < ctx->data_len) ? 0x02 : 0x00;
philpem@53 170 } else {
philpem@53 171 temp = ctx->status & ~0x01;
philpem@53 172 }
philpem@48 173 // FDC is busy if there is still data in the buffer
philpem@48 174 temp |= (ctx->data_pos < ctx->data_len) ? 0x01 : 0x00; // if data in buffer, then DMA hasn't copied it yet, and we're still busy!
philpem@49 175 // TODO: also if seek delay / read delay hasn't passed (but that's for later)
philpem@48 176 return temp;
philpem@48 177
philpem@49 178 case WD2797_REG_TRACK: // Track register
philpem@48 179 return ctx->track;
philpem@48 180
philpem@49 181 case WD2797_REG_SECTOR: // Sector register
philpem@48 182 return ctx->sector;
philpem@48 183
philpem@49 184 case WD2797_REG_DATA: // Data register
philpem@48 185 // If there's data in the buffer, return it. Otherwise return 0xFF.
philpem@48 186 if (ctx->data_pos < ctx->data_len) {
philpem@53 187 // set IRQ if this is the last data byte
philpem@53 188 if (ctx->data_pos == (ctx->data_len-1)) {
philpem@76 189 // Set IRQ
philpem@76 190 ctx->irq = true;
philpem@53 191 }
philpem@48 192 // return data byte and increment pointer
philpem@48 193 return ctx->data[ctx->data_pos++];
philpem@48 194 } else {
philpem@53 195 // command finished
philpem@48 196 return 0xff;
philpem@48 197 }
philpem@48 198
philpem@48 199 default:
philpem@48 200 // shut up annoying compilers which don't recognise unreachable code when they see it
philpem@48 201 // (here's looking at you, gcc!)
philpem@48 202 return 0xff;
philpem@48 203 }
philpem@48 204 }
philpem@48 205
philpem@48 206
philpem@49 207 void wd2797_write_reg(WD2797_CTX *ctx, uint8_t addr, uint8_t val)
philpem@48 208 {
philpem@48 209 uint8_t cmd = val & CMD_MASK;
philpem@48 210 size_t lba;
philpem@48 211 bool is_type1 = false;
philpem@49 212 int temp;
philpem@48 213
philpem@53 214 m68k_end_timeslice();
philpem@53 215
philpem@48 216 switch (addr) {
philpem@49 217 case WD2797_REG_COMMAND: // Command register
philpem@48 218 // write to command register clears interrupt request
philpem@76 219 ctx->irq = false;
philpem@48 220
philpem@48 221 // Is the drive ready?
philpem@48 222 if (ctx->disc_image == NULL) {
philpem@48 223 // No disc image, thus the drive is busy.
philpem@48 224 ctx->status = 0x80;
philpem@48 225 return;
philpem@48 226 }
philpem@48 227
philpem@48 228 // Handle Type 1 commands
philpem@48 229 switch (cmd) {
philpem@48 230 case CMD_RESTORE:
philpem@48 231 // Restore. Set track to 0 and throw an IRQ.
philpem@48 232 is_type1 = true;
philpem@48 233 ctx->track = 0;
philpem@48 234 break;
philpem@48 235
philpem@48 236 case CMD_SEEK:
philpem@48 237 // Seek. Seek to the track specced in the Data Register.
philpem@48 238 is_type1 = true;
philpem@48 239 if (ctx->data_reg < ctx->geom_tracks) {
philpem@48 240 ctx->track = ctx->data_reg;
philpem@48 241 } else {
philpem@48 242 // Seek error. :(
philpem@48 243 ctx->status = 0x10;
philpem@48 244 }
philpem@48 245
philpem@48 246 case CMD_STEP:
philpem@48 247 // TODO! deal with trk0!
philpem@48 248 // Need to keep a copy of the track register; when it hits 0, set the TRK0 flag.
philpem@48 249 is_type1 = true;
philpem@48 250 break;
philpem@48 251
philpem@48 252 case CMD_STEPIN:
philpem@48 253 case CMD_STEPOUT:
philpem@48 254 // TODO! deal with trk0!
philpem@48 255 // Need to keep a copy of the track register; when it hits 0, set the TRK0 flag.
philpem@48 256 if (cmd == CMD_STEPIN) {
philpem@48 257 ctx->last_step_dir = 1;
philpem@48 258 } else {
philpem@48 259 ctx->last_step_dir = -1;
philpem@48 260 }
philpem@48 261 is_type1 = true;
philpem@48 262 break;
philpem@48 263
philpem@48 264 case CMD_STEP_TU:
philpem@48 265 case CMD_STEPIN_TU:
philpem@48 266 case CMD_STEPOUT_TU:
philpem@48 267 // if this is a Step In or Step Out cmd, set the step-direction
philpem@48 268 if (cmd == CMD_STEPIN_TU) {
philpem@48 269 ctx->last_step_dir = 1;
philpem@48 270 } else if (cmd == CMD_STEPOUT_TU) {
philpem@48 271 ctx->last_step_dir = -1;
philpem@48 272 }
philpem@48 273
philpem@48 274 // Seek one step in the last direction used.
philpem@48 275 ctx->track += ctx->last_step_dir;
philpem@48 276 if (ctx->track < 0) ctx->track = 0;
philpem@48 277 if (ctx->track >= ctx->geom_tracks) {
philpem@48 278 // Seek past end of disc... that'll be a Seek Error then.
philpem@48 279 ctx->status = 0x10;
philpem@48 280 ctx->track = ctx->geom_tracks - 1;
philpem@48 281 }
philpem@48 282 is_type1 = true;
philpem@48 283 break;
philpem@48 284
philpem@48 285 default:
philpem@48 286 break;
philpem@48 287 }
philpem@48 288
philpem@48 289 if (is_type1) {
philpem@48 290 // Terminate any sector reads or writes
philpem@48 291 ctx->data_len = ctx->data_pos = 0;
philpem@48 292
philpem@48 293 // No DRQ bit for these commands.
philpem@48 294 ctx->cmd_has_drq = false;
philpem@48 295
philpem@48 296 // Type1 status byte...
philpem@48 297 ctx->status = 0;
philpem@48 298 // S7 = Not Ready. Command executed, therefore the drive was ready... :)
philpem@48 299 // S6 = Write Protect. TODO: add this
philpem@48 300 // S5 = Head Loaded. For certain emulation-related reasons, the heads are always loaded...
philpem@48 301 ctx->status |= 0x20;
philpem@48 302 // S4 = Seek Error. Not bloody likely if we got down here...!
philpem@48 303 // S3 = CRC Error. Not gonna happen on a disc image!
philpem@48 304 // S2 = Track 0
philpem@48 305 ctx->status |= (ctx->track == 0) ? 0x04 : 0x00;
philpem@48 306 // S1 = Index Pulse. TODO -- need periodics to emulate this
philpem@48 307 // S0 = Busy. We just exec'd the command, thus we're not busy.
philpem@48 308 // TODO: Set a timer for seeks, and ONLY clear BUSY when that timer expires. Need periodics for that.
philpem@48 309
philpem@76 310 // Set IRQ
philpem@76 311 ctx->irq = true;
philpem@48 312 return;
philpem@48 313 }
philpem@48 314
philpem@48 315 // That's the Type 1 (seek) commands sorted. Now for the others.
philpem@48 316
philpem@53 317 // All these commands return the DRQ bit...
philpem@53 318 ctx->cmd_has_drq = true;
philpem@53 319
philpem@48 320 // If drive isn't ready, then set status B7 and exit
philpem@48 321 if (ctx->disc_image == NULL) {
philpem@48 322 ctx->status = 0x80;
philpem@48 323 return;
philpem@48 324 }
philpem@48 325
philpem@48 326 // If this is a Write command, check write protect status too
philpem@48 327 // TODO!
philpem@48 328 if (false) {
philpem@48 329 // Write protected disc...
philpem@48 330 if ((cmd == CMD_WRITE_SECTOR) || (cmd == CMD_WRITE_SECTOR_MULTI) || (cmd == CMD_FORMAT_TRACK)) {
philpem@48 331 // Set Write Protect bit and bail.
philpem@48 332 ctx->status = 0x40;
philpem@48 333
philpem@76 334 // Set IRQ
philpem@76 335 ctx->irq = true;
philpem@48 336
philpem@48 337 return;
philpem@48 338 }
philpem@48 339 }
philpem@48 340
philpem@48 341 // Disc is ready to go. Parse the command word.
philpem@48 342 switch (cmd) {
philpem@48 343 case CMD_READ_ADDRESS:
philpem@48 344 // Read Address
philpem@54 345 ctx->head = (val & 0x02) ? 1 : 0;
philpem@48 346
philpem@48 347 // reset data pointers
philpem@48 348 ctx->data_pos = ctx->data_len = 0;
philpem@48 349
philpem@48 350 // load data buffer
philpem@48 351 ctx->data[ctx->data_len++] = ctx->track;
philpem@48 352 ctx->data[ctx->data_len++] = ctx->head;
philpem@48 353 ctx->data[ctx->data_len++] = ctx->sector;
philpem@48 354 switch (ctx->geom_secsz) {
philpem@48 355 case 128: ctx->data[ctx->data_len++] = 0; break;
philpem@48 356 case 256: ctx->data[ctx->data_len++] = 1; break;
philpem@48 357 case 512: ctx->data[ctx->data_len++] = 2; break;
philpem@48 358 case 1024: ctx->data[ctx->data_len++] = 3; break;
philpem@48 359 default: ctx->data[ctx->data_len++] = 0xFF; break; // TODO: deal with invalid values better
philpem@48 360 }
philpem@48 361 ctx->data[ctx->data_len++] = 0; // TODO: IDAM CRC!
philpem@48 362 ctx->data[ctx->data_len++] = 0;
philpem@48 363
philpem@53 364 ctx->status = 0;
philpem@48 365 // B6, B5 = 0
philpem@48 366 // B4 = Record Not Found. We're not going to see this... FIXME-not emulated
philpem@48 367 // B3 = CRC Error. Not possible.
philpem@48 368 // B2 = Lost Data. Caused if DRQ isn't serviced in time. FIXME-not emulated
philpem@48 369 // B1 = DRQ. Data request.
philpem@48 370 ctx->status |= (ctx->data_pos < ctx->data_len) ? 0x02 : 0x00;
philpem@48 371 break;
philpem@48 372
philpem@48 373 case CMD_READ_SECTOR:
philpem@48 374 case CMD_READ_SECTOR_MULTI:
philpem@54 375 ctx->head = (val & 0x02) ? 1 : 0;
philpem@54 376 printf("WD279X: READ SECTOR cmd=%02X chs=%d:%d:%d\n", cmd, ctx->track, ctx->head, ctx->sector);
philpem@48 377 // Read Sector or Read Sector Multiple
philpem@48 378 // reset data pointers
philpem@48 379 ctx->data_pos = ctx->data_len = 0;
philpem@48 380
philpem@49 381 // Calculate number of sectors to read from disc
philpem@49 382 if (cmd == CMD_READ_SECTOR_MULTI)
philpem@49 383 temp = ctx->geom_spt;
philpem@49 384 else
philpem@49 385 temp = 1;
philpem@48 386
philpem@49 387 for (int i=0; i<temp; i++) {
philpem@49 388 // Calculate the LBA address of the required sector
philpem@51 389 lba = ((((ctx->track * ctx->geom_heads) + ctx->head) * ctx->geom_spt) + ((ctx->sector + i - 1) % ctx->geom_spt)) * ctx->geom_secsz;
philpem@53 390 printf("\tREAD lba = %lu\n", lba);
philpem@49 391
philpem@49 392 // Read the sector from the file
philpem@49 393 fseek(ctx->disc_image, lba, SEEK_SET);
philpem@49 394 ctx->data_len += fread(&ctx->data[ctx->data_len], 1, ctx->geom_secsz, ctx->disc_image);
philpem@53 395 printf("\tREAD len=%lu, pos=%lu, ssz=%d\n", ctx->data_len, ctx->data_pos, ctx->geom_secsz);
philpem@49 396 // TODO: check fread return value! if < secsz, BAIL! (call it a crc error or secnotfound maybe? also log to stderr)
philpem@49 397 }
philpem@48 398
philpem@53 399 ctx->status = 0;
philpem@48 400 // B6 = 0
philpem@48 401 // B5 = Record Type -- 1 = deleted, 0 = normal. We can't emulate anything but normal data blocks.
philpem@48 402 // B4 = Record Not Found. We're not going to see this... FIXME-not emulated
philpem@48 403 // B3 = CRC Error. Not possible.
philpem@48 404 // B2 = Lost Data. Caused if DRQ isn't serviced in time. FIXME-not emulated
philpem@48 405 // B1 = DRQ. Data request.
philpem@48 406 ctx->status |= (ctx->data_pos < ctx->data_len) ? 0x02 : 0x00;
philpem@48 407 break;
philpem@48 408
philpem@48 409 case CMD_READ_TRACK:
philpem@48 410 // Read Track
philpem@49 411 // TODO! implement this
philpem@54 412 ctx->head = (val & 0x02) ? 1 : 0;
philpem@53 413 ctx->status = 0;
philpem@48 414 // B6, B5, B4, B3 = 0
philpem@48 415 // B2 = Lost Data. Caused if DRQ isn't serviced in time. FIXME-not emulated
philpem@48 416 // B1 = DRQ. Data request.
philpem@48 417 ctx->status |= (ctx->data_pos < ctx->data_len) ? 0x02 : 0x00;
philpem@48 418 break;
philpem@48 419
philpem@48 420 case CMD_WRITE_SECTOR:
philpem@48 421 case CMD_WRITE_SECTOR_MULTI:
philpem@48 422 // Write Sector or Write Sector Multiple
philpem@48 423
philpem@54 424 ctx->head = (val & 0x02) ? 1 : 0;
philpem@48 425 // reset data pointers
philpem@48 426 ctx->data_pos = ctx->data_len = 0;
philpem@48 427
philpem@48 428 // TODO: set "write pending" flag, and write LBA, and go from there.
philpem@48 429
philpem@53 430 ctx->status = 0;
philpem@48 431 // B6 = Write Protect. FIXME -- emulate this!
philpem@48 432 // B5 = 0
philpem@48 433 // B4 = Record Not Found. We're not going to see this... FIXME-not emulated
philpem@48 434 // B3 = CRC Error. Not possible.
philpem@48 435 // B2 = Lost Data. Caused if DRQ isn't serviced in time. FIXME-not emulated
philpem@48 436 // B1 = DRQ. Data request.
philpem@48 437 ctx->status |= (ctx->data_pos < ctx->data_len) ? 0x02 : 0x00;
philpem@48 438 break;
philpem@48 439
philpem@48 440 case CMD_FORMAT_TRACK:
philpem@48 441 // Write Track (aka Format Track)
philpem@54 442 ctx->head = (val & 0x02) ? 1 : 0;
philpem@53 443 ctx->status = 0;
philpem@48 444 // B6 = Write Protect. FIXME -- emulate this!
philpem@48 445 // B5, B4, B3 = 0
philpem@48 446 // B2 = Lost Data. Caused if DRQ isn't serviced in time. FIXME-not emulated
philpem@48 447 // B1 = DRQ. Data request.
philpem@48 448 ctx->status |= (ctx->data_pos < ctx->data_len) ? 0x02 : 0x00;
philpem@48 449 break;
philpem@48 450
philpem@48 451 case CMD_FORCE_INTERRUPT:
philpem@48 452 // Force Interrupt...
philpem@49 453 // Terminates current operation and sends an interrupt
philpem@49 454 // TODO!
philpem@53 455 ctx->status = 0;
philpem@49 456 ctx->data_pos = ctx->data_len = 0;
philpem@76 457 // Set IRQ
philpem@76 458 ctx->irq = true;
philpem@48 459 break;
philpem@48 460 }
philpem@48 461 break;
philpem@48 462
philpem@49 463 case WD2797_REG_TRACK: // Track register
philpem@48 464 ctx->track = val;
philpem@48 465 break;
philpem@48 466
philpem@49 467 case WD2797_REG_SECTOR: // Sector register
philpem@48 468 ctx->sector = val;
philpem@48 469 break;
philpem@48 470
philpem@49 471 case WD2797_REG_DATA: // Data register
philpem@48 472 // Save the value written into the data register
philpem@48 473 ctx->data_reg = val;
philpem@48 474
philpem@48 475 // If we're processing a write command, and there's space in the
philpem@48 476 // buffer, allow the write.
philpem@48 477 if (ctx->data_pos < ctx->data_len) {
philpem@53 478 // set IRQ if this is the last data byte
philpem@53 479 if (ctx->data_pos == (ctx->data_len-1)) {
philpem@76 480 // Set IRQ
philpem@76 481 ctx->irq = true;
philpem@53 482 }
philpem@53 483
philpem@48 484 // store data byte and increment pointer
philpem@48 485 ctx->data[ctx->data_pos++] = val;
philpem@48 486 }
philpem@48 487 break;
philpem@48 488 }
philpem@48 489 }
philpem@48 490