MdePkg/Library/BaseLib/AArch64/SetJumpLongJump.asm

;------------------------------------------------------------------------------
;
; Copyright (c) 2009-2013, ARM Ltd.  All rights reserved.
; SPDX-License-Identifier: BSD-2-Clause-Patent
;
;------------------------------------------------------------------------------

  EXPORT SetJump
  EXPORT InternalLongJump
  EXTERN InternalAssertJumpBuffer
  AREA BaseLib_LowLevel, CODE, READONLY

#define GPR_LAYOUT                          \
        REG_PAIR (x19, x20,  #0);           \
        REG_PAIR (x21, x22, #16);           \
        REG_PAIR (x23, x24, #32);           \
        REG_PAIR (x25, x26, #48);           \
        REG_PAIR (x27, x28, #64);           \
        REG_PAIR (x29, x30, #80);/*FP, LR*/ \
        REG_ONE  (x16,      #96) /*IP0*/

#define FPR_LAYOUT                       \
        REG_PAIR ( d8,  d9, #104);       \
        REG_PAIR (d10, d11, #120);       \
        REG_PAIR (d12, d13, #136);       \
        REG_PAIR (d14, d15, #152);

;/**
;  Saves the current CPU context that can be restored with a call to LongJump() and returns 0.#
;
;  Saves the current CPU context in the buffer specified by JumpBuffer and returns 0.  The initial
;  call to SetJump() must always return 0.  Subsequent calls to LongJump() cause a non-zero
;  value to be returned by SetJump().
;
;  If JumpBuffer is NULL, then ASSERT().
;
;  @param  JumpBuffer    A pointer to CPU context buffer.
;
;**/
;
;UINTN
;EFIAPI
;SetJump (
;  IN      BASE_LIBRARY_JUMP_BUFFER  *JumpBuffer  // X0
;  );
;
SetJump
#ifndef MDEPKG_NDEBUG
        stp     x29, x30, [sp, #-32]!
        mov     x29, sp
        str     x0, [sp, #16]
        bl      InternalAssertJumpBuffer
        ldr     x0, [sp, #16]
        ldp     x29, x30, [sp], #32
#endif
        mov     x16, sp // use IP0 so save SP
#define REG_PAIR(REG1, REG2, OFFS)      stp REG1, REG2, [x0, OFFS]
#define REG_ONE(REG1, OFFS)             str REG1, [x0, OFFS]
        GPR_LAYOUT
        FPR_LAYOUT
#undef REG_PAIR
#undef REG_ONE
        mov     x0, #0
        ret

;/**
;  Restores the CPU context that was saved with SetJump().#
;
;  Restores the CPU context from the buffer specified by JumpBuffer.
;  This function never returns to the caller.
;  Instead it resumes execution based on the state of JumpBuffer.
;
;  @param  JumpBuffer    A pointer to CPU context buffer.
;  @param  Value         The value to return when the SetJump() context is restored.
;
;**/
;VOID
;EFIAPI
;InternalLongJump (
;  IN      BASE_LIBRARY_JUMP_BUFFER  *JumpBuffer,  // X0
;  IN      UINTN                     Value         // X1
;  );
;
InternalLongJump
#define REG_PAIR(REG1, REG2, OFFS)      ldp REG1, REG2, [x0, OFFS]
#define REG_ONE(REG1, OFFS)             ldr REG1, [x0, OFFS]
        GPR_LAYOUT
        FPR_LAYOUT
#undef REG_PAIR
#undef REG_ONE
        mov     sp, x16
        cmp     x1, #0
        mov     x0, #1
        beq     exit
        mov     x0, x1
exit
        // use br not ret, as ret is guaranteed to mispredict
        br      x30

ASM_FUNCTION_REMOVE_IF_UNREFERENCED

  END