i386/ucla/src/lab5/lib/ipc.c

   1 // User-level IPC library routines
   2
   3 #include <inc/lib.h>
   4
   5 // Receive a value via IPC and return it.
   6 // If 'pg' is nonnull, then any page sent by the sender will be mapped at
   7 //      that address.
   8 // If 'from_env_store' is nonnull, then store the IPC sender's envid in
   9 //      *from_env_store.
  10 // If 'perm_store' is nonnull, then store the IPC sender's page permission
  11 //      in *perm_store (this is nonzero iff a page was successfully
  12 //      transferred to 'pg').
  13 // If the system call fails, then store 0 in *fromenv and *perm (if
  14 //      they're nonnull) and return the error.
  15 // Otherwise, return the value sent by the sender
  16 //
  17 // Hint:
  18 //   Use 'thisenv' to discover the value and who sent it.
  19 //   If 'pg' is null, pass sys_ipc_recv a value that it will understand
  20 //   as meaning "no page".  (Zero is not the right value, since that's
  21 //   a perfectly valid place to map a page.)
  22 int32_t
  23 ipc_recv(envid_t *from_env_store, void *pg, int *perm_store)
  24 {
  25         // LAB 4: Your code here.
  26         panic("ipc_recv not implemented");
  27         return 0;
  28 }
  29
  30 // Send 'val' (and 'pg' with 'perm', if 'pg' is nonnull) to 'toenv'.
  31 // This function keeps trying until it succeeds.
  32 // It should panic() on any error other than -E_IPC_NOT_RECV.
  33 //
  34 // Hint:
  35 //   Use sys_yield() to be CPU-friendly.
  36 //   If 'pg' is null, pass sys_ipc_recv a value that it will understand
  37 //   as meaning "no page".  (Zero is not the right value.)
  38 void
  39 ipc_send(envid_t to_env, uint32_t val, void *pg, int perm)
  40 {
  41         // LAB 4: Your code here.
  42         panic("ipc_send not implemented");
  43 }