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#define EXC_VECTORS          8
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#define EXC_VECTORS          8
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/** Size of memory block occupied by exception vectors. */
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/** Size of memory block occupied by exception vectors. */
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#define EXC_VECTORS_SIZE     (EXC_VECTORS * 4)
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#define EXC_VECTORS_SIZE     (EXC_VECTORS * 4)
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/** Switches to kernel stack and saves all registers there.
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 *
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 * Temporary exception stack is used to save a few registers
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 * before stack switch takes place.
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 *
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 *  The stack fram created by the function looks like:
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 *
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 *      |_________________|
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 *      |                 |
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 *      |     SPSR        |
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 *      |                 |
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 *      |_________________|
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 *      | Stack Pointer   |
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 *      |      of         |
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 *      | Previous Mode   |
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 *      |_________________|
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 *      | Return address  |
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 *      |      of         |
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 *      | Previous Mode   |
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 *      |_________________|
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 *      |   R0  - R12     |
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 *      |      of         |
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 *      | Previous Mode   |
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 *      |_________________|
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 *      | Return address  |
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 *      |     from        |
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 *      |Exception Handler|
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 *      |_________________|
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 *      |                 |
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 *
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 */
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inline static void setup_stack_and_save_regs()
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{
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    asm volatile (
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        "ldr r13, =exc_stack\n"
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        "stmfd r13!, {r0-r3}\n"
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        "mrs r1, cpsr\n"
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        "bic r1, r1, #0x1f\n"
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        "mrs r2, spsr\n"
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        "and r0, r2, #0x1f\n"
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        "cmp r0, #0x10\n"
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        "bne 1f\n"
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        /* prev mode was usermode */
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        "mov r0, sp\n"
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        "mov r3, lr\n"
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        /* Switch to supervisor mode */
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        "orr r1, r1, #0x13\n"
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        "msr cpsr_c, r1\n"
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        /* Load sp with [supervisor_sp] */
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        "ldr r13, =supervisor_sp\n"
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        "ldr r13, [r13]\n"
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        /* Populate the stack frame */
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        "msr spsr, r2\n"
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        "mov lr, r3\n"
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        "stmfd r13!, {lr}\n"
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        "stmfd r13!, {r4-r12}\n"
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        "ldmfd r0!, {r4-r7}\n"
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        "stmfd r13!, {r4-r7}\n"
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        "stmfd r13!, {r13, lr}^\n"
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        "stmfd r13!, {r2}\n"
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        "b 2f\n"
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        /* mode was not usermode */
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        "1:\n"
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            /* Switch to previous mode which is undoubtedly the supervisor mode */
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            "orr r1, r1, r0\n"
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            "mov r0, lr\n"
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            "mov r3, sp\n"
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            "msr cpsr_c, r1\n"
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            /* Populate the stack frame */
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            "mov r1, sp\n"
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            "stmfd r13!, {r0}\n"
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            "stmfd r13!, {r4-r12}\n"
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            /* Store r0-r3 in r4-r7 and then push it on to stack */
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            "ldmfd r3!, {r4-r7}\n"
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            "stmfd r13!, {r4-r7}\n"
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            /* Push return address and stack pointer on to stack */
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            "stmfd r13!, {lr}\n"
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            "stmfd r13!, {r1}\n"
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            "mov lr, r0\n"
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            "msr spsr, r2\n"
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            "stmfd r13!, {r2}\n"
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        "2:\n"
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    );
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}
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/** Returns from exception mode.
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 *
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 * Previously saved state of registers (including control register)
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 * is restored from the stack.
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 */
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inline static void load_regs()
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{
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    asm volatile(
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        "ldmfd r13!, {r0}       \n"
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        "msr spsr, r0           \n"
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        "and r0, r0, #0x1f      \n"
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        "cmp r0, #0x10          \n"
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        "bne 1f             \n"
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        /* return to user mode */
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        "ldmfd r13!, {r13, lr}^     \n"
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        "b 2f               \n"
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        /* return to non-user mode */
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    "1:\n"
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        "ldmfd r13!, {r1, r2}       \n"
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        "mrs r3, cpsr           \n"
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        "bic r3, r3, #0x1f      \n"
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        "orr r3, r3, r0         \n"
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        "mrs r0, cpsr           \n"
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        "msr cpsr_c, r3         \n"
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        "mov lr, r2         \n"
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        "msr cpsr_c, r0         \n"
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        /* actual return */
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    "2:\n"
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        "ldmfd r13!, {r0-r12, pc}^\n"
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189 
    );
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190 
}
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/** Calls exception dispatch routine. */
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#define CALL_EXC_DISPATCH(exception) \
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195 
    asm volatile ( \
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        "mov r0, %[exc]\n" \
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        "mov r1, r13\n" \
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        "bl exc_dispatch\n" \
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        :: [exc] "i" (exception) \
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200 
    );\
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/** General exception handler.
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203 
 *
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 *  Stores registers, dispatches the exception,
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205 
 *  and finally restores registers and returns from exception processing.
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206 
 *
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 *  @param exception Exception number.
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 */
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#define PROCESS_EXCEPTION(exception) \
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    setup_stack_and_save_regs(); \
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211 
    CALL_EXC_DISPATCH(exception) \
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212 
    load_regs();
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/** Updates specified exception vector to jump to given handler.
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/** Updates specified exception vector to jump to given handler.
215 
 *
 62 
 *
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 *  Addresses of handlers are stored in memory following exception vectors.
 63 
 *  Addresses of handlers are stored in memory following exception vectors.
217 
 */
 64 
 */
218 
static void install_handler(unsigned handler_addr, unsigned *vector)
 65 
static void install_handler(unsigned handler_addr, unsigned *vector)
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    /* store handler's address */
 77 
    /* store handler's address */
231 
    *(vector + EXC_VECTORS) = handler_addr;
 78 
    *(vector + EXC_VECTORS) = handler_addr;
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 79 
 
233 
}
 80 
}
234 
 
 81 
 
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/** Low-level Reset Exception handler. */
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236 
static void reset_exception_entry(void)
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237 
{
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238 
    PROCESS_EXCEPTION(EXC_RESET);
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239 
}
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/** Low-level Software Interrupt Exception handler. */
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static void swi_exception_entry(void)
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243 
{
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244 
    PROCESS_EXCEPTION(EXC_SWI);
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245 
}
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/** Low-level Undefined Instruction Exception handler. */
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static void undef_instr_exception_entry(void)
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249 
{
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    PROCESS_EXCEPTION(EXC_UNDEF_INSTR);
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}
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/** Low-level Fast Interrupt Exception handler. */
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254 
static void fiq_exception_entry(void)
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255 
{
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256 
    PROCESS_EXCEPTION(EXC_FIQ);
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257 
}
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/** Low-level Prefetch Abort Exception handler. */
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260 
static void prefetch_abort_exception_entry(void)
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261 
{
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262 
    asm volatile (
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263 
        "sub lr, lr, #4"
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264 
    );
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265 
   
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    PROCESS_EXCEPTION(EXC_PREFETCH_ABORT);
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}
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/** Low-level Data Abort Exception handler. */
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270 
static void data_abort_exception_entry(void)
 - 
 
271 
{
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272 
    asm volatile (
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273 
        "sub lr, lr, #8"
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274 
    );
 - 
 
275 
   
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276 
    PROCESS_EXCEPTION(EXC_DATA_ABORT);
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}
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/** Low-level Interrupt Exception handler.
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280 
 *
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281 
 * CPU is switched to Undefined mode before further interrupt processing
 - 
 
282 
 * because of possible occurence of nested interrupt exception, which
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283 
 * would overwrite (and thus spoil) stack pointer.
 - 
 
284 
 */
 - 
 
285 
static void irq_exception_entry(void)
 - 
 
286 
{
 - 
 
287 
    asm volatile (
 - 
 
288 
        "sub lr, lr, #4"
 - 
 
289 
    );
 - 
 
290 
   
 - 
 
291 
    PROCESS_EXCEPTION(EXC_IRQ)
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292 
}
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/** Software Interrupt handler.
 82 
/** Software Interrupt handler.
295 
 *
 83 
 *
296 
 * Dispatches the syscall.
 84 
 * Dispatches the syscall.
297 
 */
 85 
 */
298 
static void swi_exception(int exc_no, istate_t *istate)
 86 
static void swi_exception(int exc_no, istate_t *istate)