+ Add missing implementation of pipe syscall

git-svn-id: trunk@21859 -

rtl/linux/mips/bsyscall.inc

@@ -17,9 +17,19 @@ Function fppipe(var fildes : tfildes):cint;assembler;
 {
   This function puts the registers in place, does the call, and then
   copies back the registers as they are after the SysCall.
+  Extracted from linux/source/arch/mips/kernel/syscall.c:
+  * For historic reasons the pipe(2) syscall on MIPS has an unusual calling
+  * convention.  It returns results in registers $v0 / $v1 which means there
+  * is no need for it to do verify the validity of a userspace pointer
+  * argument.  Historically that used to be expensive in Linux.  These days
+  * the performance advantage is negligible.
 }
 asm
-// At present it is NOT IMPLEMENTED for MIPS
-// simplified-work
-// DavidZhang
+  li $v0,syscall_nr_pipe
+  syscall
+  { the two files descriptors are now in v0 and v1 registers 
+    copying them back into fildes variable }
+  lw $t1,fildes
+  sw $v0,($t1)
+  sw $v1,4($t1)
 end;