111 lines
2.7 KiB
C
111 lines
2.7 KiB
C
#include <stdint.h>
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#include <stdio.h>
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#include <unistd.h>
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#include "encoding.h"
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#include "platform.h"
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extern int main(int argc, char** argv);
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extern void trap_entry(void);
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#define IRQ_M_SOFT 3
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#define IRQ_M_TIMER 7
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#define IRQ_M_EXT 11
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void handle_m_ext_interrupt(void);
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void handle_m_time_interrupt(void);
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uint32_t handle_trap(uint32_t mcause, uint32_t mepc, uint32_t sp);
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void default_handler(void);
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void _init(void);
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typedef void (*my_interrupt_function_ptr_t)(void);
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my_interrupt_function_ptr_t localISR[NUM_INTERRUPTS] __attribute__((aligned(64)));
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static unsigned long mtime_lo(void) {
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unsigned long ret;
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__asm volatile("rdtime %0" : "=r"(ret));
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return ret;
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}
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#if __riscv_xlen == 32
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static uint32_t mtime_hi(void) {
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unsigned long ret;
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__asm volatile("rdtimeh %0" : "=r"(ret));
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return ret;
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}
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uint64_t get_timer_value(void) {
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while(1) {
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uint32_t hi = mtime_hi();
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uint32_t lo = mtime_lo();
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if(hi == mtime_hi())
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return ((uint64_t)hi << 32) | lo;
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}
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}
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#elif __riscv_xlen == 64
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uint64_t get_timer_value() { return mtime_lo(); }
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#endif
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unsigned long get_timer_freq() { return 32768; }
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unsigned long get_cpu_freq() { return 100000000; }
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void init_pll(void) {
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// TODO: implement initialization
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}
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static void uart_init(size_t baud_rate) {
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// TODO: implement initialization
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}
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void __attribute__((weak)) handle_m_ext_interrupt() {}
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void __attribute__((weak)) handle_m_time_interrupt() {
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uint64_t time = get_aclint_mtime(aclint);
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time += MTIMER_NEXT_TICK_INC;
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set_aclint_mtimecmp(aclint, time);
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}
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void __attribute__((weak)) default_handler(void) { puts("default handler\n"); }
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void __attribute__((weak)) interrupt_handler(unsigned) { puts("interrupt handler\n"); }
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uint32_t handle_trap(uint32_t mcause, uint32_t mepc, uint32_t sp) {
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if((mcause & MCAUSE_INT)) {
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if((mcause & MCAUSE_CAUSE) == IRQ_M_EXT) {
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handle_m_ext_interrupt();
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} else if(((mcause & MCAUSE_CAUSE) == IRQ_M_TIMER)) {
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handle_m_time_interrupt();
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} else {
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interrupt_handler(mcause & ~MCAUSE_INT);
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}
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} else {
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write(1, "trap\n", 5);
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_exit(1 + mcause);
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}
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return mepc;
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}
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void __attribute__((weak)) _init() {
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#ifndef NO_INIT
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init_pll();
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uart_init(115200);
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printf("core freq at %lu Hz\n", get_cpu_freq());
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write_csr(mtvec, &trap_entry);
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if(read_csr(misa) & (1 << ('F' - 'A'))) { // if F extension is present
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write_csr(mstatus, MSTATUS_FS); // allow FPU instructions without trapping
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write_csr(fcsr, 0); // initialize rounding mode, undefined at reset
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}
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int i = 0;
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while(i < NUM_INTERRUPTS) {
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localISR[i++] = default_handler;
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}
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#endif
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}
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void _fini(void) {}
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