splits low_level_init to allow usage of c file

this also makes threadx hook into the isrs

port/moonlight/src/trap_non_vectored.c

@@ -3,8 +3,6 @@
 #include "riscv-traps.h"
 #include <stdint.h>
 #include <stdio.h>
-#include <tx_api.h>
-#include <tx_port.h>
 
 #if __riscv_xlen == 64
 #define INTERRUPT_BIT 0x8000000000000000ull
@@ -16,7 +14,6 @@
 #define OS_IS_SOFT_INT(mcause) (mcause == (0x3 | INTERRUPT_BIT))
 #define OS_IS_EXT_INT(mcause) (mcause == (0xb | INTERRUPT_BIT))
 
-extern void _tx_timer_interrupt(void);
 extern uintptr_t exception(uintptr_t mcause, uintptr_t mepc, uintptr_t mtval);
 
 void (*irq_handler[__riscv_xlen])();
@@ -33,23 +30,13 @@ void trap_handler(uintptr_t mcause, uintptr_t mepc, uintptr_t mtval) {
     if(OS_IS_INTERRUPT(mcause)) {
         unsigned irq_id = mcause&(__riscv_xlen-1);
         switch(irq_id){
-            case RISCV_INT_MTI:
-#ifdef NX_DEBUG
-                printf("Timer interrupt being handled (pc=%lx)\n", mepc);
-#endif
-                hwtimer_handler();
-                _tx_timer_interrupt();
-                break;
+/*    
 #ifdef TX_THREAD_SMP_INTER_CORE_INTERRUPT
             case RISCV_INT_MSI:
                 set_aclint_msip(aclint, csr_read_mhartid(), 0);
                 break;
 #endif
-            case RISCV_INT_MEI:
-                puts("[INTERRUPT]: handler ext irq error!\n");
-                while(1)
-                    ;
-                break;
+*/
             default:
                 if(irq_handler[irq_id])
                     irq_handler[irq_id]();