adds RISCV-VP platform

env/riscv_vp/init.c

@@ -0,0 +1,138 @@
+#include <stdint.h>
+#include <stdio.h>
+#include <unistd.h>
+
+#include "platform.h"
+#include "encoding.h"
+
+
+extern int main(int argc, char** argv);
+extern void trap_entry(void);
+#define IRQ_M_SOFT   3
+#define IRQ_M_TIMER  7
+#define IRQ_M_EXT    11
+
+#define NUM_INTERRUPTS 16
+#define MTIMER_NEXT_TICK_INC 1000
+
+void handle_m_ext_interrupt(void);
+void handle_m_time_interrupt(void);
+uint32_t handle_trap(uint32_t mcause, uint32_t mepc, uint32_t sp);
+void default_handler(void);
+void _init(void);
+
+typedef void (*my_interrupt_function_ptr_t) (void);
+my_interrupt_function_ptr_t localISR[NUM_INTERRUPTS] __attribute__((aligned(64)));
+
+static unsigned long mtime_lo(void)
+{
+    unsigned long ret;
+    __asm volatile("rdtime %0":"=r"(ret));
+    return ret;
+}
+
+
+#if __riscv_xlen==32
+
+static uint32_t mtime_hi(void)
+{
+    unsigned long ret;
+    __asm volatile("rdtimeh %0":"=r"(ret));
+    return ret;
+}
+
+uint64_t get_timer_value(void)
+{
+  while (1) {
+    uint32_t hi = mtime_hi();
+    uint32_t lo = mtime_lo();
+    if (hi == mtime_hi())
+      return ((uint64_t)hi << 32) | lo;
+  }
+}
+
+#elif __riscv_xlen==64
+
+uint64_t get_timer_value()
+{
+  return mtime_lo();
+}
+
+#endif
+
+unsigned long get_timer_freq()
+{
+  return 32768;
+}
+
+unsigned long get_cpu_freq()
+{
+  return 100000000;
+}
+
+void init_pll(void){
+    //TODO: implement initialization
+}
+
+static void uart_init(size_t baud_rate)
+{
+  //TODO: implement initialization
+}
+
+void __attribute__((weak)) handle_m_ext_interrupt(){
+}
+
+void __attribute__((weak)) handle_m_time_interrupt(){
+  uint64_t time = get_aclint_mtime(aclint);
+  time+=MTIMER_NEXT_TICK_INC;
+  set_aclint_mtimecmp(aclint, time);
+}
+
+void __attribute__((weak)) default_handler(void) {
+  puts("default handler\n");
+}
+
+void __attribute__((weak)) interrupt_handler(unsigned) {
+  puts("interrupt handler\n");
+}
+
+uint32_t handle_trap(uint32_t mcause, uint32_t mepc, uint32_t sp){
+  if ((mcause & MCAUSE_INT)) {
+    if ((mcause & MCAUSE_CAUSE) == IRQ_M_EXT) {
+      handle_m_ext_interrupt();
+    } else if (((mcause & MCAUSE_CAUSE) == IRQ_M_TIMER)){ 
+      handle_m_time_interrupt();
+    } else {
+      interrupt_handler(mcause& ~MCAUSE_INT);
+    }
+  } else {
+    write(1, "trap\n", 5);
+    _exit(1 + mcause);
+  }
+  return mepc;
+}
+
+void _init()
+{
+  
+#ifndef NO_INIT
+  init_pll();
+  uart_init(115200);
+  printf("core freq at %lu Hz\n", get_cpu_freq());
+  write_csr(mtvec, &trap_entry);
+  if (read_csr(misa) & (1 << ('F' - 'A'))) { // if F extension is present
+    write_csr(mstatus, MSTATUS_FS); // allow FPU instructions without trapping
+    write_csr(fcsr, 0); // initialize rounding mode, undefined at reset
+  }
+  int i=0;
+  while(i<NUM_INTERRUPTS)  {
+    localISR[i++] = default_handler;
+  }
+
+#endif
+  
+}
+
+void _fini(void)
+{
+}