root/platform/a720/sub/100c/boot.c

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DEFINITIONS

This source file includes following definitions.
  1. CreateTask_spytask
  2. taskCreateHook
  3. boot
  4. sub_FFC001A4_my
  5. sub_FFC00FB8_my
  6. uHwSetup_my
  7. CreateTask_Startup_my
  8. task_Startup_my
  9. taskcreatePhySw_my
  10. init_file_modules_task
  11. sub_FFC5A4E8_my
  12. sub_FFC3F0CC_my
  13. sub_FFC3EF08_my
  14. sub_FFC3EDA0_my

   1 /*
   2  * boot.c - auto-generated by CHDK code_gen.
   3  */
   4 #include "lolevel.h"
   5 #include "platform.h"
   6 #include "core.h"
   7 
   8 const char * const new_sa = &_end;
   9 
  10 /*----------------------------------------------------------------------
  11     CreateTask_spytask
  12 -----------------------------------------------------------------------*/
  13 void CreateTask_spytask()
  14 {
  15     _CreateTask("SpyTask", 0x19, 0x2000, core_spytask, 0);
  16 }
  17 
  18 void taskCreateHook(int *p) {
  19     p-=16;
  20     if (p[0]==0xffc4cb64)  p[0]=(int)capt_seq_task;
  21     if (p[0]==0xffc91454)  p[0]=(int)exp_drv_task;
  22     if (p[0]==0xffc49b18)  p[0]=(int)movie_record_task;
  23     if (p[0]==0xffdbfc80)  p[0]=(int)filewritetask;
  24     if (p[0]==0xffc5f754)  p[0]=(int)init_file_modules_task;
  25 }
  26 
  27 void boot()
  28 {
  29     long *canon_data_src = (void*)0xFFE9C5D0;
  30     long *canon_data_dst = (void*)0x1900;
  31     long canon_data_len = 0xf0c4 - 0x1900; // data_end - data_start
  32     long *canon_bss_start = (void*)0xf0c4; // just after data
  33     long canon_bss_len = 0x9d024 - 0xf0c4;
  34 
  35     long i;
  36 
  37 
  38     // Enable CPU caches and MPU
  39     asm volatile (
  40     "MRC     p15, 0, R0,c1,c0\n"
  41     "ORR     R0, R0, #0x1000\n"
  42     "ORR     R0, R0, #4\n"
  43     "ORR     R0, R0, #1\n"
  44     "MCR     p15, 0, R0,c1,c0\n"
  45     :::"r0");
  46 
  47     for(i=0;i<canon_data_len/4;i++)
  48     canon_data_dst[i]=canon_data_src[i];
  49 
  50     for(i=0;i<canon_bss_len/4;i++)
  51     canon_bss_start[i]=0;
  52 
  53    *(int*)0x1930=(int)taskCreateHook;
  54    *(int*)0x1934=(int)taskCreateHook;
  55 
  56     // jump to init-sequence that follows the data-copy-routine
  57     asm volatile ("B      sub_FFC001A4_my\n");
  58 };
  59 
  60 
  61 /*************************************************************/
  62 //** sub_FFC001A4_my @ 0xFFC001A4 - 0xFFC0020C, length=27
  63 void __attribute__((naked,noinline)) sub_FFC001A4_my() {
  64 asm volatile (
  65 "    LDR     R0, =0xFFC0021C \n"
  66 "    MOV     R1, #0 \n"
  67 "    LDR     R3, =0xFFC00254 \n"
  68 
  69 "loc_FFC001B0:\n"
  70 "    CMP     R0, R3 \n"
  71 "    LDRCC   R2, [R0], #4 \n"
  72 "    STRCC   R2, [R1], #4 \n"
  73 "    BCC     loc_FFC001B0 \n"
  74 "    LDR     R0, =0xFFC00254 \n"
  75 "    MOV     R1, #0x4B0 \n"
  76 "    LDR     R3, =0xFFC00468 \n"
  77 
  78 "loc_FFC001CC:\n"
  79 "    CMP     R0, R3 \n"
  80 "    LDRCC   R2, [R0], #4 \n"
  81 "    STRCC   R2, [R1], #4 \n"
  82 "    BCC     loc_FFC001CC \n"
  83 "    MOV     R0, #0xD2 \n"
  84 "    MSR     CPSR_cxsf, R0 \n"
  85 "    MOV     SP, #0x1000 \n"
  86 "    MOV     R0, #0xD3 \n"
  87 "    MSR     CPSR_cxsf, R0 \n"
  88 "    MOV     SP, #0x1000 \n"
  89 "    LDR     R0, =0x6C4 \n"
  90 "    LDR     R2, =0xEEEEEEEE \n"
  91 "    MOV     R3, #0x1000 \n"
  92 
  93 "loc_FFC00200:\n"
  94 "    CMP     R0, R3 \n"
  95 "    STRCC   R2, [R0], #4 \n"
  96 "    BCC     loc_FFC00200 \n"
  97 "    BL      sub_FFC00FB8_my \n"  // --> Patched. Old value = 0xFFC00FB8.
  98 );
  99 }
 100 
 101 /*************************************************************/
 102 //** sub_FFC00FB8_my @ 0xFFC00FB8 - 0xFFC01058, length=41
 103 void __attribute__((naked,noinline)) sub_FFC00FB8_my() {
 104 asm volatile (
 105 "    STR     LR, [SP, #-4]! \n"
 106 "    SUB     SP, SP, #0x74 \n"
 107 "    MOV     R0, SP \n"
 108 "    MOV     R1, #0x74 \n"
 109 "    BL      sub_FFE3B620 \n"
 110 "    MOV     R0, #0x53000 \n"
 111 "    STR     R0, [SP, #4] \n"
 112 
 113 #if defined(CHDK_NOT_IN_CANON_HEAP) // use original heap offset if CHDK is loaded in high memory
 114 "    LDR     R0, =0x9D024 \n"
 115 #else
 116 "    LDR     R0, =new_sa\n"   // otherwise use patched value
 117 "    LDR     R0, [R0]\n"      //
 118 #endif
 119 
 120 "    LDR     R2, =0x2ABC00 \n"
 121 "    LDR     R1, =0x2A4968 \n"
 122 "    STR     R0, [SP, #8] \n"
 123 "    SUB     R0, R1, R0 \n"
 124 "    ADD     R3, SP, #0xC \n"
 125 "    STR     R2, [SP] \n"
 126 "    STMIA   R3, {R0-R2} \n"
 127 "    MOV     R0, #0x22 \n"
 128 "    STR     R0, [SP, #0x18] \n"
 129 "    MOV     R0, #0x68 \n"
 130 "    STR     R0, [SP, #0x1C] \n"
 131 "    LDR     R0, =0x19B \n"
 132 "    MOV     R1, #0x64 \n"
 133 "    STRD    R0, [SP, #0x20] \n"
 134 "    MOV     R0, #0x78 \n"
 135 "    STRD    R0, [SP, #0x28] \n"
 136 "    MOV     R0, #0 \n"
 137 "    STR     R0, [SP, #0x30] \n"
 138 "    STR     R0, [SP, #0x34] \n"
 139 "    MOV     R0, #0x10 \n"
 140 "    STR     R0, [SP, #0x5C] \n"
 141 "    MOV     R0, #0x800 \n"
 142 "    STR     R0, [SP, #0x60] \n"
 143 "    MOV     R0, #0xA0 \n"
 144 "    STR     R0, [SP, #0x64] \n"
 145 "    MOV     R0, #0x280 \n"
 146 "    STR     R0, [SP, #0x68] \n"
 147 "    LDR     R1, =uHwSetup_my \n"  // --> Patched. Old value = 0xFFC04DBC.
 148 "    MOV     R0, SP \n"
 149 "    MOV     R2, #0 \n"
 150 "    BL      sub_FFC02D70 \n"
 151 "    ADD     SP, SP, #0x74 \n"
 152 "    LDR     PC, [SP], #4 \n"
 153 );
 154 }
 155 
 156 /*************************************************************/
 157 //** uHwSetup_my @ 0xFFC04DBC - 0xFFC04E30, length=30
 158 void __attribute__((naked,noinline)) uHwSetup_my() {
 159 asm volatile (
 160 "    STMFD   SP!, {R4,LR} \n"
 161 "    BL      sub_FFC0095C \n"
 162 "    BL      sub_FFC09A18 \n"
 163 "    CMP     R0, #0 \n"
 164 "    LDRLT   R0, =0xFFC04ED0 /*'dmSetup'*/ \n"
 165 "    BLLT    _err_init_task \n"
 166 "    BL      sub_FFC049E0 \n"
 167 "    CMP     R0, #0 \n"
 168 "    LDRLT   R0, =0xFFC04ED8 /*'termDriverInit'*/ \n"
 169 "    BLLT    _err_init_task \n"
 170 "    LDR     R0, =0xFFC04EE8 /*'/_term'*/ \n"
 171 "    BL      sub_FFC04ACC \n"
 172 "    CMP     R0, #0 \n"
 173 "    LDRLT   R0, =0xFFC04EF0 /*'termDeviceCreate'*/ \n"
 174 "    BLLT    _err_init_task \n"
 175 "    LDR     R0, =0xFFC04EE8 /*'/_term'*/ \n"
 176 "    BL      sub_FFC0357C \n"
 177 "    CMP     R0, #0 \n"
 178 "    LDRLT   R0, =0xFFC04F04 /*'stdioSetup'*/ \n"
 179 "    BLLT    _err_init_task \n"
 180 "    BL      sub_FFC095A0 \n"
 181 "    CMP     R0, #0 \n"
 182 "    LDRLT   R0, =0xFFC04F10 /*'stdlibSetup'*/ \n"
 183 "    BLLT    _err_init_task \n"
 184 "    BL      sub_FFC014D0 \n"
 185 "    CMP     R0, #0 \n"
 186 "    LDRLT   R0, =0xFFC04F1C /*'armlib_setup'*/ \n"
 187 "    BLLT    _err_init_task \n"
 188 "    LDMFD   SP!, {R4,LR} \n"
 189 "    B       CreateTask_Startup_my \n"  // --> Patched. Old value = 0xFFC0DCDC.
 190 );
 191 }
 192 
 193 /*************************************************************/
 194 //** CreateTask_Startup_my @ 0xFFC0DCDC - 0xFFC0DD44, length=27
 195 void __attribute__((naked,noinline)) CreateTask_Startup_my() {
 196 asm volatile (
 197 "    STMFD   SP!, {R3,LR} \n"
 198 //"  BL      _sub_FFC12E08 \n"  // --> Nullsub call removed.
 199 "    BL      sub_FFC1B9BC \n"
 200 "    CMP     R0, #0 \n"
 201 "    LDREQ   R0, =0xC0220000 \n"
 202 "    LDREQ   R1, [R0, #0xB8] \n"
 203 "    TSTEQ   R1, #1 \n"
 204 "    BNE     loc_FFC0DD08 \n"
 205 "    MOV     R1, #0x44 \n"
 206 "    STR     R1, [R0, #0x4C] \n"
 207 
 208 "loc_FFC0DD04:\n"
 209 "    B       loc_FFC0DD04 \n"
 210 
 211 "loc_FFC0DD08:\n"
 212 //"  BL      _sub_FFC12E10 \n"  // --> Nullsub call removed.
 213 //"  BL      _sub_FFC12E0C \n"  // --> Nullsub call removed.
 214 "    BL      sub_FFC19548 \n"
 215 "    MOV     R1, #0x300000 \n"
 216 "    MOV     R0, #0 \n"
 217 "    BL      sub_FFC19790 \n"
 218 "    BL      sub_FFC1973C \n"
 219 "    MOV     R3, #0 \n"
 220 "    STR     R3, [SP] \n"
 221 "    LDR     R3, =task_Startup_my \n"  // --> Patched. Old value = 0xFFC0DC80.
 222 "    MOV     R2, #0 \n"
 223 "    MOV     R1, #0x19 \n"
 224 "    LDR     R0, =0xFFC0DD4C /*'Startup'*/ \n"
 225 "    BL      _CreateTask \n"
 226 "    MOV     R0, #0 \n"
 227 "    LDMFD   SP!, {R12,PC} \n"
 228 );
 229 }
 230 
 231 /*************************************************************/
 232 //** task_Startup_my @ 0xFFC0DC80 - 0xFFC0DCD8, length=23
 233 void __attribute__((naked,noinline)) task_Startup_my() {
 234 asm volatile (
 235 "    STMFD   SP!, {R4,LR} \n"
 236 "    BL      sub_FFC051CC \n"
 237 "    BL      sub_FFC13FA8 \n"
 238 "    BL      sub_FFC10EA4 \n"
 239 "    BL      sub_FFC370E8 \n"
 240 "    BL      sub_FFC1BB9C \n"
 241 //"  BL      _sub_FFC1BA84 \n"  // load DISKBOOT.BIN
 242 "    BL      CreateTask_spytask\n" // added
 243 "    BL      sub_FFC5C18C \n"
 244 "    BL      sub_FFC1BBEC \n"
 245 "    BL      sub_FFC18A8C \n"
 246 "    BL      sub_FFC1BD68 \n"
 247 "    BL      taskcreatePhySw_my \n"  // --> Patched. Old value = 0xFFC12DAC. Checks buttons and acts accordingly
 248 "    BL      sub_FFC15BC8 \n"
 249 "    BL      sub_FFC1BD80 \n"
 250 //"  BL      _sub_FFC10BBC \n"  // --> Nullsub call removed.
 251 "    BL      sub_FFC1213C \n"
 252 "    BL      sub_FFC1B768 \n"
 253 "    BL      sub_FFC128D8 \n"
 254 "    BL      sub_FFC12048 \n"
 255 "    BL      sub_FFC1C6C4 \n"
 256 "    BL      sub_FFC12004 \n"
 257 "    LDMFD   SP!, {R4,LR} \n"
 258 "    B       sub_FFC05088 \n"
 259 );
 260 }
 261 
 262 /*************************************************************/
 263 //** taskcreatePhySw_my @ 0xFFC12DAC - 0xFFC12DE0, length=14
 264 void __attribute__((naked,noinline)) taskcreatePhySw_my() {
 265 asm volatile (
 266 "    STMFD   SP!, {R3-R5,LR} \n"
 267 "    LDR     R4, =0x1C98 \n"
 268 "    LDR     R0, [R4, #0x10] \n"
 269 "    CMP     R0, #0 \n"
 270 "    BNE     loc_FFC12DE0 \n"
 271 "    MOV     R3, #0 \n"
 272 "    STR     R3, [SP] \n"
 273 "    LDR     R3, =mykbd_task \n"  // --> Patched. Old value = 0xFFC12D78.
 274 "    MOV     R2, #0x800 \n"
 275 "    MOV     R1, #0x17 \n"
 276 "    LDR     R0, =0xFFC12FA0 /*'PhySw'*/ \n"
 277 "    BL      sub_FFC0BE98 /*_CreateTaskStrictly*/ \n"
 278 "    STR     R0, [R4, #0x10] \n"
 279 
 280 "loc_FFC12DE0:\n"
 281 "    LDMFD   SP!, {R3-R5,PC} \n"
 282 );
 283 }
 284 
 285 /*************************************************************/
 286 //** init_file_modules_task @ 0xFFC5F754 - 0xFFC5F788, length=14
 287 void __attribute__((naked,noinline)) init_file_modules_task() {
 288 asm volatile (
 289 "    STMFD   SP!, {R4-R6,LR} \n"
 290 "    BL      sub_FFC5A4BC \n"
 291 "    LDR     R5, =0x5006 \n"
 292 "    MOVS    R4, R0 \n"
 293 "    MOVNE   R1, #0 \n"
 294 "    MOVNE   R0, R5 \n"
 295 "    BLNE    _PostLogicalEventToUI \n"
 296 "    BL      sub_FFC5A4E8_my \n"  // --> Patched. Old value = 0xFFC5A4E8.
 297 "    BL      core_spytask_can_start\n"  // CHDK: Set "it's-safe-to-start" flag for spytask
 298 "    CMP     R4, #0 \n"
 299 "    MOVEQ   R0, R5 \n"
 300 "    LDMEQFD SP!, {R4-R6,LR} \n"
 301 "    MOVEQ   R1, #0 \n"
 302 "    BEQ     _PostLogicalEventToUI \n"
 303 "    LDMFD   SP!, {R4-R6,PC} \n"
 304 );
 305 }
 306 
 307 /*************************************************************/
 308 //** sub_FFC5A4E8_my @ 0xFFC5A4E8 - 0xFFC5A520, length=15
 309 void __attribute__((naked,noinline)) sub_FFC5A4E8_my() {
 310 asm volatile (
 311 "    STMFD   SP!, {R4,LR} \n"
 312 "    BL      sub_FFC3F0CC_my \n"  // --> Patched. Old value = 0xFFC3F0CC.
 313 "    LDR     R4, =0x58D0 \n"
 314 "    LDR     R0, [R4, #4] \n"
 315 "    CMP     R0, #0 \n"
 316 "    BNE     loc_FFC5A518 \n"
 317 "    BL      sub_FFC674CC \n"
 318 "    BL      sub_FFCDCA24 \n"
 319 "    BL      sub_FFC674CC \n"
 320 "    BL      sub_FFCE6504 \n"
 321 "    BL      sub_FFC674DC \n"
 322 "    BL      sub_FFCDCAC4 \n"
 323 
 324 "loc_FFC5A518:\n"
 325 "    MOV     R0, #1 \n"
 326 "    STR     R0, [R4] \n"
 327 "    LDMFD   SP!, {R4,PC} \n"
 328 );
 329 }
 330 
 331 /*************************************************************/
 332 //** sub_FFC3F0CC_my @ 0xFFC3F0CC - 0xFFC3F164, length=39
 333 void __attribute__((naked,noinline)) sub_FFC3F0CC_my() {
 334 asm volatile (
 335 "    STMFD   SP!, {R4-R6,LR} \n"
 336 "    MOV     R6, #0 \n"
 337 "    MOV     R0, R6 \n"
 338 "    BL      sub_FFC3EC9C \n"
 339 "    LDR     R4, =0x11800 \n"
 340 "    MOV     R5, #0 \n"
 341 "    LDR     R0, [R4, #0x38] \n"
 342 "    BL      sub_FFC3F664 \n"
 343 "    CMP     R0, #0 \n"
 344 "    LDREQ   R0, =0x2BA0 \n"
 345 "    STREQ   R5, [R0, #0xC] \n"
 346 "    STREQ   R5, [R0, #0x10] \n"
 347 "    STREQ   R5, [R0, #0x14] \n"
 348 "    MOV     R0, R6 \n"
 349 "    BL      sub_FFC3ECDC \n"
 350 "    MOV     R0, R6 \n"
 351 "    BL      sub_FFC3EF08_my \n"  // --> Patched. Old value = 0xFFC3EF08.
 352 "    MOV     R5, R0 \n"
 353 "    MOV     R0, R6 \n"
 354 "    BL      sub_FFC3EF74 \n"
 355 "    LDR     R1, [R4, #0x3C] \n"
 356 "    AND     R2, R5, R0 \n"
 357 "    CMP     R1, #0 \n"
 358 "    MOV     R0, #0 \n"
 359 "    MOVEQ   R0, #0x80000001 \n"
 360 "    BEQ     loc_FFC3F160 \n"
 361 "    LDR     R3, [R4, #0x2C] \n"
 362 "    CMP     R3, #2 \n"
 363 "    MOVEQ   R0, #4 \n"
 364 "    CMP     R1, #5 \n"
 365 "    ORRNE   R0, R0, #1 \n"
 366 "    BICEQ   R0, R0, #1 \n"
 367 "    CMP     R2, #0 \n"
 368 "    BICEQ   R0, R0, #2 \n"
 369 "    ORREQ   R0, R0, #0x80000000 \n"
 370 "    BICNE   R0, R0, #0x80000000 \n"
 371 "    ORRNE   R0, R0, #2 \n"
 372 
 373 "loc_FFC3F160:\n"
 374 "    STR     R0, [R4, #0x40] \n"
 375 "    LDMFD   SP!, {R4-R6,PC} \n"
 376 );
 377 }
 378 
 379 /*************************************************************/
 380 //** sub_FFC3EF08_my @ 0xFFC3EF08 - 0xFFC3EF70, length=27
 381 void __attribute__((naked,noinline)) sub_FFC3EF08_my() {
 382 asm volatile (
 383 "    STMFD   SP!, {R4-R6,LR} \n"
 384 "    LDR     R5, =0x2BA0 \n"
 385 "    MOV     R6, R0 \n"
 386 "    LDR     R0, [R5, #0x10] \n"
 387 "    CMP     R0, #0 \n"
 388 "    MOVNE   R0, #1 \n"
 389 "    LDMNEFD SP!, {R4-R6,PC} \n"
 390 "    MOV     R0, #0x17 \n"
 391 "    MUL     R1, R0, R6 \n"
 392 "    LDR     R0, =0x11800 \n"
 393 "    ADD     R4, R0, R1, LSL#2 \n"
 394 "    LDR     R0, [R4, #0x38] \n"
 395 "    MOV     R1, R6 \n"
 396 "    BL      sub_FFC3EDA0_my \n"  // --> Patched. Old value = 0xFFC3EDA0.
 397 "    CMP     R0, #0 \n"
 398 "    LDMEQFD SP!, {R4-R6,PC} \n"
 399 "    LDR     R0, [R4, #0x38] \n"
 400 "    MOV     R1, R6 \n"
 401 "    BL      sub_FFC3F77C \n"
 402 "    CMP     R0, #0 \n"
 403 "    LDMEQFD SP!, {R4-R6,PC} \n"
 404 "    MOV     R0, R6 \n"
 405 "    BL      sub_FFC3E8BC \n"
 406 "    CMP     R0, #0 \n"
 407 "    MOVNE   R1, #1 \n"
 408 "    STRNE   R1, [R5, #0x10] \n"
 409 "    LDMFD   SP!, {R4-R6,PC} \n"
 410 );
 411 }
 412 
 413 /*************************************************************/
 414 //** sub_FFC3EDA0_my @ 0xFFC3EDA0 - 0xFFC3EF04, length=90
 415 void __attribute__((naked,noinline)) sub_FFC3EDA0_my() {
 416 asm volatile (
 417 "    STMFD   SP!, {R4-R8,LR} \n"
 418 "    MOV     R8, R0 \n"
 419 "    MOV     R0, #0x17 \n"
 420 "    MUL     R1, R0, R1 \n"
 421 "    LDR     R0, =0x11800 \n"
 422 "    MOV     R6, #0 \n"
 423 "    ADD     R7, R0, R1, LSL#2 \n"
 424 "    LDR     R0, [R7, #0x3C] \n"
 425 "    MOV     R5, #0 \n"
 426 "    CMP     R0, #6 \n"
 427 "    ADDLS   PC, PC, R0, LSL#2 \n"
 428 "    B       loc_FFC3EEEC \n"
 429 "    B       loc_FFC3EE04 \n"
 430 "    B       loc_FFC3EDEC \n"
 431 "    B       loc_FFC3EDEC \n"
 432 "    B       loc_FFC3EDEC \n"
 433 "    B       loc_FFC3EDEC \n"
 434 "    B       loc_FFC3EEE4 \n"
 435 "    B       loc_FFC3EDEC \n"
 436 
 437 "loc_FFC3EDEC:\n"
 438 "    MOV     R2, #0 \n"
 439 "    MOV     R1, #0x200 \n"
 440 "    MOV     R0, #3 \n"
 441 "    BL      sub_FFC56994 \n"
 442 "    MOVS    R4, R0 \n"
 443 "    BNE     loc_FFC3EE0C \n"
 444 
 445 "loc_FFC3EE04:\n"
 446 "    MOV     R0, #0 \n"
 447 "    LDMFD   SP!, {R4-R8,PC} \n"
 448 
 449 "loc_FFC3EE0C:\n"
 450 "    LDR     R12, [R7, #0x4C] \n"
 451 "    MOV     R3, R4 \n"
 452 "    MOV     R2, #1 \n"
 453 "    MOV     R1, #0 \n"
 454 "    MOV     R0, R8 \n"
 455 "    BLX     R12 \n"
 456 "    CMP     R0, #1 \n"
 457 "    BNE     loc_FFC3EE38 \n"
 458 "    MOV     R0, #3 \n"
 459 "    BL      sub_FFC56AD4 \n"
 460 "    B       loc_FFC3EE04 \n"
 461 
 462 "loc_FFC3EE38:\n"
 463 "    MOV     R0, R8 \n"
 464 "    BL      sub_FFCF554C \n"
 465 
 466 "    MOV     R1, R4\n"              //  pointer to MBR in R1
 467 "    BL      mbr_read_dryos\n"      //  total sectors count in R0 before and after call
 468 
 469 // Start of DataGhost's FAT32 autodetection code
 470 // Policy: If there is a partition which has type W95 FAT32, use the first one of those for image storage
 471 // According to the code below, we can use R1, R2, R3 and R12.
 472 // LR wasn't really used anywhere but for storing a part of the partition signature. This is the only thing
 473 // that won't work with an offset, but since we can load from LR+offset into LR, we can use this to do that :)
 474 "    MOV     R12, R4\n"             // Copy the MBR start address so we have something to work with
 475 "    MOV     LR, R4\n"              // Save old offset for MBR signature
 476 "    MOV     R1, #1\n"              // Note the current partition number
 477 "    B       dg_sd_fat32_enter\n"   // We actually need to check the first partition as well, no increments yet!
 478 "dg_sd_fat32:\n"
 479 "    CMP     R1, #4\n"              // Did we already see the 4th partition?
 480 "    BEQ     dg_sd_fat32_end\n"     // Yes, break. We didn't find anything, so don't change anything.
 481 "    ADD     R12, R12, #0x10\n"     // Second partition
 482 "    ADD     R1, R1, #1\n"          // Second partition for the loop
 483 "dg_sd_fat32_enter:\n"
 484 "    LDRB    R2, [R12, #0x1BE]\n"   // Partition status
 485 "    LDRB    R3, [R12, #0x1C2]\n"   // Partition type (FAT32 = 0xB)
 486 "    CMP     R3, #0xB\n"            // Is this a FAT32 partition?
 487 "    CMPNE   R3, #0xC\n"            // Not 0xB, is it 0xC (FAT32 LBA) then?
 488 "    CMPNE   R3, #0x7\n"            // exFat?
 489 "    BNE     dg_sd_fat32\n"         // No, it isn't. Loop again.
 490 "    CMP     R2, #0x00\n"           // It is, check the validity of the partition type
 491 "    CMPNE   R2, #0x80\n"
 492 "    BNE     dg_sd_fat32\n"         // Invalid, go to next partition
 493                                     // This partition is valid, it's the first one, bingo!
 494 "    MOV     R4, R12\n"             // Move the new MBR offset for the partition detection.
 495 
 496 "dg_sd_fat32_end:\n"
 497 // End of DataGhost's FAT32 autodetection code
 498 
 499 "    LDRB    R1, [R4, #0x1C9] \n"
 500 "    LDRB    R3, [R4, #0x1C8] \n"
 501 "    LDRB    R12, [R4, #0x1CC] \n"
 502 "    MOV     R1, R1, LSL#24 \n"
 503 "    ORR     R1, R1, R3, LSL#16 \n"
 504 "    LDRB    R3, [R4, #0x1C7] \n"
 505 "    LDRB    R2, [R4, #0x1BE] \n"
 506 //"  LDRB    LR, [R4, #0x1FF] \n"
 507 "    ORR     R1, R1, R3, LSL#8 \n"
 508 "    LDRB    R3, [R4, #0x1C6] \n"
 509 "    CMP     R2, #0 \n"
 510 "    CMPNE   R2, #0x80 \n"
 511 "    ORR     R1, R1, R3 \n"
 512 "    LDRB    R3, [R4, #0x1CD] \n"
 513 "    MOV     R3, R3, LSL#24 \n"
 514 "    ORR     R3, R3, R12, LSL#16 \n"
 515 "    LDRB    R12, [R4, #0x1CB] \n"
 516 "    ORR     R3, R3, R12, LSL#8 \n"
 517 "    LDRB    R12, [R4, #0x1CA] \n"
 518 "    ORR     R3, R3, R12 \n"
 519 //"  LDRB    R12, [R4, #0x1FE] \n"  // Replaced, see below
 520 //mod start
 521 "    LDRB    R12, [LR,#0x1FE]\n"           // New! First MBR signature byte (0x55)
 522 "    LDRB    LR, [LR,#0x1FF]\n"            //      Last MBR signature byte (0xAA)
 523 //mod end
 524 "    MOV     R4, #0 \n"
 525 "    BNE     loc_FFC3EEC0 \n"
 526 "    CMP     R0, R1 \n"
 527 "    BCC     loc_FFC3EEC0 \n"
 528 "    ADD     R2, R1, R3 \n"
 529 "    CMP     R2, R0 \n"
 530 "    CMPLS   R12, #0x55 \n"
 531 "    CMPEQ   LR, #0xAA \n"
 532 "    MOVEQ   R6, R1 \n"
 533 "    MOVEQ   R5, R3 \n"
 534 "    MOVEQ   R4, #1 \n"
 535 
 536 "loc_FFC3EEC0:\n"
 537 "    MOV     R0, #3 \n"
 538 "    BL      sub_FFC56AD4 \n"
 539 "    CMP     R4, #0 \n"
 540 "    BNE     loc_FFC3EEF8 \n"
 541 "    MOV     R6, #0 \n"
 542 "    MOV     R0, R8 \n"
 543 "    BL      sub_FFCF554C \n"
 544 "    MOV     R5, R0 \n"
 545 "    B       loc_FFC3EEF8 \n"
 546 
 547 "loc_FFC3EEE4:\n"
 548 "    MOV     R5, #0x40 \n"
 549 "    B       loc_FFC3EEF8 \n"
 550 
 551 "loc_FFC3EEEC:\n"
 552 "    LDR     R1, =0x365 \n"
 553 "    LDR     R0, =0xFFC3ED94 /*'Mounter.c'*/ \n"
 554 "    BL      _DebugAssert \n"
 555 
 556 "loc_FFC3EEF8:\n"
 557 "    STR     R6, [R7, #0x44]! \n"
 558 "    MOV     R0, #1 \n"
 559 "    STR     R5, [R7, #4] \n"
 560 "    LDMFD   SP!, {R4-R8,PC} \n"
 561 );
 562 }

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