Add waitpid and execve

arch/aarch64.c

@@ -81,6 +81,50 @@ uint32_t fork(){
   return (uint32_t)rtn;
 }
 
+// SYS_EXECVE 221
+int32_t execve(const char* filename, const char* argv[], const char* envp[]){
+  long int rtn;
+  asm volatile( 
+    // Assembly Instructions
+    "mov x0, %0\n"  // Set x0 to value of filename
+    "mov x1, %1\n"  // Set x1 to value of argv
+    "mov x2, %2\n"  // Set x2 to value of envp
+    "mov x8, #221\n" // Syscall number
+    "svc #0\n"      // Make syscall
+    // Output operands
+    : "=r"(rtn)
+    // Input operands
+    : "r"(filename), "r" (argv), "r"(envp)
+    // Clobbered registers
+    : "x0", "x1", "x2", "x8", "memory"
+  );
+  return (int32_t)rtn;
+}
+
+uint32_t wait4(uint32_t pid, int* wstatus, int options, void* rusage) {
+  uint64_t rtn;
+  asm volatile (
+    // Assembly Instructions
+    "mov x8, #260\n"  // Syscall number for 'listen' is 201 in AArch64
+    "mov x0, %1\n"    // pid
+    "mov x1, %2\n"    // wstatus  
+    "mov x2, %3\n"    // options
+    "mov x3, %4\n"    // rusage
+    "svc #0\n"        // Make the syscall
+    "mov %0, x0\n"    // save return value
+    // Output operands
+    : "=r" (rtn)
+    // Input operand
+    : "r" ((uint64_t)pid), "r"(wstatus), "r"((int64_t)options), "r"(rusage)
+    // Clobbered registers
+    : "x0", "x1", "x8", "memory"
+  );
+  return (uint32_t)rtn;
+}
+uint32_t waitpid(uint32_t pid, int* wstatus, int options) {
+  return wait4(pid, wstatus, options, 0);
+}
+
 int32_t openat(int32_t fd, const char* filename, uint32_t flags, uint32_t mode) {
   long int rtn;
   asm volatile (