/*
 * Copyright (c) 2007 Matthew Dillon <dillon@backplane.com>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Neither the name of the author nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */
/*
 * swapcontext_quick() and setcontext_quick().  There is *NO*
 * getcontext_quick() routine on purpose.
 *
 * Quick routines are not required to save or resetore scratch registers,
 * FP regs (which are scratch), or flags.
 */
#include <machine/asm.h>
#include <cpu/specialreg.h>
#include <asmcontext.h>

        /*
         * void setcontext_quick(ucontext_t *ucp)
         *
         * Load the register context, effectively switching to the
         * new context.
         */
        .weak   setcontext_quick
        .set    setcontext_quick,_setcontext_quick
ENTRY(_setcontext_quick)
        addq    $UC_MCONTEXT,%rdi

        /*      MC_ONSTACK(%rdi)        */
        /*      MC_RDI(%rdi)    - see below */
        movq    MC_RSI(%rdi),%rsi
        movq    MC_RDX(%rdi),%rdx
        movq    MC_R8(%rdi),%r8
        movq    MC_R9(%rdi),%r9
        /*      MC_RAX(%rdi)    - see below */
        movq    MC_RBX(%rdi),%rbx
        movq    MC_RCX(%rdi),%rcx
        movq    MC_RBP(%rdi),%rbp
        movq    MC_R10(%rdi),%r10
        movq    MC_R11(%rdi),%r11
        movq    MC_R12(%rdi),%r12
        movq    MC_R13(%rdi),%r13
        movq    MC_R14(%rdi),%r14
        movq    MC_R15(%rdi),%r15
        /*      MC_TRAPNO(%rdi) */
        /*      MC_ADDR(%rdi)   */
        /*      MC_FLAGS(%rdi)  */
        /*      MC_ERR(%rdi)    */
        /*      MC_RIP(%rdi)    - see below */
        /*      MC_CS(%rdi)     */
        /*      MC_RFLAGS(%rdi) */
        /*      MC_RSP(%rdi)    - see below */
        /*      MC_SS(%rdi)     */

        /*
         * Load the new stack pointer
         */
        movq    MC_RSP(%rdi),%rsp

        /*
         * Use %rax to hold the return pc.  function returns void.  Do
         * not mess with the target stack (particularly not the red-zone!).
         */
        movq    MC_RIP(%rdi),%rax

        /*
         * Finally rdi
         */
        movq    MC_RDI(%rdi),%rdi
        jmp     *%rax
END(_setcontext_quick)


        /*
         * void swapcontext_quick(ucontex_t *oucp, ucontext_t *nucp)
         *
         * Save the current state in oucp and switch to nucp.
         */
        .weak   swapcontext_quick
        .set    swapcontext_quick,_swapcontext_quick
ENTRY(_swapcontext_quick)
        /*
         * Save
         */
        addq    $UC_MCONTEXT,%rdi
        popq    %rax                    /* return pc */

        movq    %rsi,MC_RSI(%rdi)
        movq    %rbx,MC_RBX(%rdi)
        movq    %rdx,MC_RDX(%rdi)
        movq    %rbp,MC_RBP(%rdi)
        movq    %r10,MC_R10(%rdi)
        movq    %r11,MC_R11(%rdi)
        movq    %r12,MC_R12(%rdi)
        movq    %r13,MC_R13(%rdi)
        movq    %r14,MC_R14(%rdi)
        movq    %r15,MC_R15(%rdi)
        movq    %rsp,MC_RSP(%rdi)
        movq    %rax,MC_RIP(%rdi)

        /*
         * Restore (copy of setcontext above)
         */
        movq    %rsi,%rdi
        addq    $UC_MCONTEXT,%rdi

        /*      MC_ONSTACK(%rdi)        */
        /*      MC_RDI(%rdi)    - see below */
        movq    MC_RSI(%rdi),%rsi
        movq    MC_RDX(%rdi),%rdx
        /*      MC_RAX(%rdi)    - see below */
        movq    MC_RBX(%rdi),%rbx
        movq    MC_RCX(%rdi),%rcx
        movq    MC_RBP(%rdi),%rbp
        movq    MC_R10(%rdi),%r10
        movq    MC_R11(%rdi),%r11
        movq    MC_R12(%rdi),%r12
        movq    MC_R13(%rdi),%r13
        movq    MC_R14(%rdi),%r14
        movq    MC_R15(%rdi),%r15
        /*      MC_TRAPNO(%rdi) */
        /*      MC_ADDR(%rdi)   */
        /*      MC_FLAGS(%rdi)  */
        /*      MC_ERR(%rdi)    */
        /*      MC_RIP(%rdi)    - see below */
        /*      MC_CS(%rdi)     */
        /*      MC_RFLAGS(%rdi) */
        /*      MC_RSP(%rdi)    - see below */
        /*      MC_SS(%rdi)     */

        /*
         * Load the new stack pointer
         */
        movq    MC_RSP(%rdi),%rsp

        /*
         * Use %rax to hold the return pc.  function returns void.  Do
         * not mess with the target stack (particularly not the red-zone!).
         */
        movq    MC_RIP(%rdi),%rax

        /*
         * Finally rdi
         */
        movq    MC_RDI(%rdi),%rdi
        jmp     *%rax

END(_swapcontext_quick)

        .section .note.GNU-stack,"",%progbits