| Line 215... |
Line 215... |
return cycles.uint64;
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return cycles.uint64;
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}
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}
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/**********************************************************************//**
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/**********************************************************************//**
|
* Simple delay function (not very precise) using busy wait.
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* Simple delay function using busy wait.
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*
|
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* @warning This function requires the cycle CSR(s). Hence, the Zicsr extension is mandatory.
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*
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*
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* @param[in] time_ms Time in ms to wait.
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* @param[in] time_ms Time in ms to wait.
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**************************************************************************/
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**************************************************************************/
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void neorv32_cpu_delay_ms(uint32_t time_ms) {
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void neorv32_cpu_delay_ms(uint32_t time_ms) {
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|
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uint32_t clock_speed = SYSINFO_CLK >> 10; // fake divide by 1000
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uint64_t time_resume = neorv32_cpu_get_cycle();
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clock_speed = clock_speed >> 5; // divide by loop execution time (~30 cycles)
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uint32_t cnt = clock_speed * time_ms;
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uint32_t clock = SYSINFO_CLK; // clock ticks per second
|
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clock = clock / 1000; // clock ticks per ms
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// one iteration = ~30 cycles
|
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while (cnt) {
|
uint64_t wait_cycles = ((uint64_t)clock) * ((uint64_t)time_ms);
|
asm volatile("nop");
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time_resume += wait_cycles;
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asm volatile("nop");
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asm volatile("nop");
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while(1) {
|
asm volatile("nop");
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if (neorv32_cpu_get_cycle() >= time_resume) {
|
cnt--;
|
break;
|
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}
|
}
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}
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}
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}
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/**********************************************************************//**
|
/**********************************************************************//**
|
* Switch from privilege mode MACHINE to privilege mode USER.
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* Switch from privilege mode MACHINE to privilege mode USER.
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*
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*
|
* @note This function requires the U extension to be implemented.
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* @warning This function requires the U extension to be implemented.
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* @note Maybe you should do a fence.i after this.
|
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**************************************************************************/
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**************************************************************************/
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void __attribute__((naked)) neorv32_cpu_goto_user_mode(void) {
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void __attribute__((naked)) neorv32_cpu_goto_user_mode(void) {
|
|
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// make sure to use NO registers in here! -> naked
|
// make sure to use NO registers in here! -> naked
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|
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asm volatile ("csrw mepc, ra \n\t" // move return address to mepc so we can return using "mret". also, we can use ra as general purpose register in here
|
asm volatile ("csrw mepc, ra \n\t" // move return address to mepc so we can return using "mret". also, we can now use ra as general purpose register in here
|
"li ra, %[input_imm] \n\t" // bit mask to clear the two MPP bits
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"li ra, %[input_imm] \n\t" // bit mask to clear the two MPP bits
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"csrrc zero, mstatus, ra \n\t" // clear MPP bits -> MPP=u-mode
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"csrrc zero, mstatus, ra \n\t" // clear MPP bits -> MPP=u-mode
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"mret \n\t" // return and switch to user mode
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"mret \n\t" // return and switch to user mode
|
: : [input_imm] "i" ((1<<CPU_MSTATUS_MPP_H) | (1<<CPU_MSTATUS_MPP_L)));
|
: : [input_imm] "i" ((1<<CPU_MSTATUS_MPP_H) | (1<<CPU_MSTATUS_MPP_L)));
|
}
|
}
|
|
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No newline at end of file
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No newline at end of file
|
|
|
|
/**********************************************************************//**
|
|
* Atomic compare-and-swap operation (for implemeneting semaphores and mutexes).
|
|
*
|
|
* @warning This function requires the A (atomic) CPU extension.
|
|
*
|
|
* @param[in] addr Address of memory location.
|
|
* @param[in] expected Expected value (for comparison).
|
|
* @param[in] desired Desired value (new value).
|
|
* @return Returns 0 on success, 1 on failure.
|
|
**************************************************************************/
|
|
int __attribute__ ((noinline)) neorv32_cpu_atomic_cas(uint32_t addr, uint32_t expected, uint32_t desired) {
|
|
#ifdef __riscv_atomic
|
|
|
|
register uint32_t addr_reg = addr;
|
|
register uint32_t des_reg = desired;
|
|
register uint32_t tmp_reg;
|
|
|
|
// load original value + reservation (lock)
|
|
asm volatile ("lr.w %[result], (%[input])" : [result] "=r" (tmp_reg) : [input] "r" (addr_reg));
|
|
|
|
if (tmp_reg != expected) {
|
|
asm volatile ("lw x0, 0(%[input])" : : [input] "r" (addr_reg)); // clear reservation lock
|
|
return 1;
|
|
}
|
|
|
|
// store-conditional
|
|
asm volatile ("sc.w %[result], %[input_i], (%[input_j])" : [result] "=r" (tmp_reg) : [input_i] "r" (des_reg), [input_j] "r" (addr_reg));
|
|
|
|
if (tmp_reg) {
|
|
return 1;
|
|
}
|
|
|
|
return 0;
|
|
#else
|
|
return 1; // A extension not implemented -Y always fail
|
|
#endif
|
|
}
|
|
|
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|
No newline at end of file
|
