c76ed560c0
git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@5426 42af7a65-404d-4744-a932-0658087f49c3
144 lines
4.4 KiB
NASM
144 lines
4.4 KiB
NASM
;*************************************************************************
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; arch/z80/src/z180/z180_saveusercontext.asm
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;
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; Copyright (C) 2012 Gregory Nutt. All rights reserved.
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; Author: Gregory Nutt <gnutt@nuttx.org>
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;
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; Redistribution and use in source and binary forms, with or without
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; modification, are permitted provided that the following conditions
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; are met:
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;
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; 1. Redistributions of source code must retain the above copyright
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; notice, this list of conditions and the following disclaimer.
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; 2. Redistributions in binary form must reproduce the above copyright
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; notice, this list of conditions and the following disclaimer in
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; the documentation and/or other materials provided with the
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; distribution.
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; 3. Neither the name NuttX nor the names of its contributors may be
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; used to endorse or promote products derived from this software
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; without specific prior written permission.
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;
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; THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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; "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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; LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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; FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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; COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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; INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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; BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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; OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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; AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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; LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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; ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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; POSSIBILITY OF SUCH DAMAGE.
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;
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;*************************************************************************
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;*************************************************************************
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; Constants
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;*************************************************************************
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; Register save area layout
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.globl XCPT_I ; Offset 0: Saved I w/interrupt state in parity
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.globl XCPT_BC ; Offset 1: Saved BC register
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.globl XCPT_DE ; Offset 2: Saved DE register
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.globl XCPT_IX ; Offset 3: Saved IX register
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.globl XCPT_IY ; Offset 4: Saved IY register
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.globl XCPT_SP ; Offset 5: Offset to SP at time of interrupt
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.globl XCPT_HL ; Offset 6: Saved HL register
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.globl XCPT_AF ; Offset 7: Saved AF register
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.globl XCPT_PC ; Offset 8: Offset to PC at time of interrupt
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; Stack frame
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FRAME_IY == 0 ; Location of IY on the stack
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FRAME_IX == 2 ; Location of IX on the stack
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FRAME_RET == 4 ; Location of return address on the stack
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FRAME_REGS == 6 ; Location of reg save area on stack
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SP_OFFSET == 6
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;*************************************************************************
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; Name: z180_saveusercontext
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;*************************************************************************
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.area _CODE
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_z180_saveusercontext:
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; Set up a stack frame
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push ix ; Save IX and IY
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push iy
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ld ix, #0
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add ix, sp ; IX = stack frame
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; Fetch the address of the save area
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ld e, FRAME_REGS(ix) ; HL = save area address
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ld d, FRAME_REGS+1(ix) ;
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ld iy, #0
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add iy, de ; IY = save area address
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; Then save the registers
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; Save the current interrupt state at offset 0
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ld a, i ; Get interrupt state
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push af
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pop hl
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ld XCPT_I(iy), l ; Offset 0: I w/interrupt state in parity
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ld XCPT_I+1(iy), h
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; Save BC at offset 1
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ld XCPT_BC(iy), c ; Offset 1: BC
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ld XCPT_BC+1(iy), b
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; DE is not preserved (offset 2)
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; Save IX at offset 3
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ld l, FRAME_IX(ix) ; HL = Saved alue of IX
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ld h, FRAME_IX+1(ix) ;
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ld XCPT_IX(iy), l ; Offset 3: IX
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ld XCPT_IX+1(iy), h ;
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; Save IY at offset 4
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ld l, FRAME_IY(ix) ; HL = Saved value of IY
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ld h, FRAME_IY+1(ix) ;
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ld XCPT_IY(iy), l ; Offset 4: IY
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ld XCPT_IY+1(iy), h
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; Save that stack pointer as it would be upon return in offset 5
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ld hl, #SP_OFFSET ; Value of stack pointer on return
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add hl, sp
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ld XCPT_SP(iy), l ; Offset 5 SP
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ld XCPT_SP+1(iy), h
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; HL is saved as the value 1 at offset 6
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xor a ; A = 0
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ld XCPT_HL+1(iy), a ; Offset 2: HL on return (=1)
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inc a ; A = 1
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ld XCPT_HL(iy), a ;
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; AF is not preserved (offset 7)
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; Save the return address in offset 8
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ld l, FRAME_RET(ix) ; HL = Saved return address
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ld h, FRAME_RET+1(ix) ;
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ld XCPT_PC(iy), l ; Offset 8: PC
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ld XCPT_PC+1(iy), h
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; Return the value 0
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xor a ; HL = return value of zero
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ld l, a
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ld h, a
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pop iy
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pop ix
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ret
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