#

# Context switch for AMD64 small model.  (Position-independent code.)

#

# See http://www.amd64.org/ for information about AMD64 programming.

#

        .file       "rswitch.s"

        .section    .rodata

.L0:    .string     "new_context() returned in coswitch"

        .globl      coswitch

        .text

        .globl      coswitch

        .type       coswitch, @function

coswitch:

        # coswitch(old_cstate, new_cstate, first)

        #

        #     %rdi     old_cstate

        #     %rsi     new_cstate

        #     %edx     first (equals 0 if first activation)

        #

        movq    %rsp, 0(%rdi)      # Old stack pointer -> old_cstate[0]

        movq    0(%rsi), %rsp      # new_cstate[0] -> new stack pointer

        orl     %edx, %edx         # Is this the first activation?

        je      .L1                # If so, skip.

        ret                        # Otherwise we are done.

.L1:    xorl    %edi, %edi         # Call new_context((int) 0, (ptr) 0)

        xorl    %esi, %esi         # (Implicitly zero-extended to 64 bits)

        call    new_context@PLT

        leaq    .L0(%rip), %rdi    # Call syserr(...)

        movl    $0, %eax

        jmp     syserr@PLT

else

   ARCH=`uname -p 2>/dev/null || echo unknown`

   if [ "$ARCH" = "unknown" ]; then

      ARCH=`uname -m`

   fi