1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
|
;*************************************************************************
; arch/z80/src/z180/z180_saveusercontext.asm
;
; Copyright (C) 2012 Gregory Nutt. All rights reserved.
; Author: Gregory Nutt <gnutt@nuttx.org>
;
; 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. Redistributions in binary form must reproduce the above copyright
; notice, this list of conditions and the following disclaimer in
; the documentation and/or other materials provided with the
; distribution.
; 3. Neither the name NuttX 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 COPYRIGHT HOLDERS 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
; COPYRIGHT OWNER 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.
;
;*************************************************************************
;*************************************************************************
; Constants
;*************************************************************************
; Register save area layout
.globl XCPT_I ; Offset 0: Saved I w/interrupt state in parity
.globl XCPT_BC ; Offset 1: Saved BC register
.globl XCPT_DE ; Offset 2: Saved DE register
.globl XCPT_IX ; Offset 3: Saved IX register
.globl XCPT_IY ; Offset 4: Saved IY register
.globl XCPT_SP ; Offset 5: Offset to SP at time of interrupt
.globl XCPT_HL ; Offset 6: Saved HL register
.globl XCPT_AF ; Offset 7: Saved AF register
.globl XCPT_PC ; Offset 8: Offset to PC at time of interrupt
; Stack frame
FRAME_IY == 0 ; Location of IY on the stack
FRAME_IX == 2 ; Location of IX on the stack
FRAME_RET == 4 ; Location of return address on the stack
FRAME_REGS == 6 ; Location of reg save area on stack
SP_OFFSET == 6
;*************************************************************************
; Name: z180_saveusercontext
;*************************************************************************
.area _CODE
_z180_saveusercontext:
; Set up a stack frame
push ix ; Save IX and IY
push iy
ld ix, #0
add ix, sp ; IX = stack frame
; Fetch the address of the save area
ld e, FRAME_REGS(ix) ; HL = save area address
ld d, FRAME_REGS+1(ix) ;
ld iy, #0
add iy, de ; IY = save area address
; Then save the registers
; Save the current interrupt state at offset 0
ld a, i ; Get interrupt state
push af
pop hl
ld XCPT_I(iy), l ; Offset 0: I w/interrupt state in parity
ld XCPT_I+1(iy), h
; Save BC at offset 1
ld XCPT_BC(iy), c ; Offset 1: BC
ld XCPT_BC+1(iy), b
; DE is not preserved (offset 2)
; Save IX at offset 3
ld l, FRAME_IX(ix) ; HL = Saved alue of IX
ld h, FRAME_IX+1(ix) ;
ld XCPT_IX(iy), l ; Offset 3: IX
ld XCPT_IX+1(iy), h ;
; Save IY at offset 4
ld l, FRAME_IY(ix) ; HL = Saved value of IY
ld h, FRAME_IY+1(ix) ;
ld XCPT_IY(iy), l ; Offset 4: IY
ld XCPT_IY+1(iy), h
; Save that stack pointer as it would be upon return in offset 5
ld hl, #SP_OFFSET ; Value of stack pointer on return
add hl, sp
ld XCPT_SP(iy), l ; Offset 5 SP
ld XCPT_SP+1(iy), h
; HL is saved as the value 1 at offset 6
xor a ; A = 0
ld XCPT_HL+1(iy), a ; Offset 2: HL on return (=1)
inc a ; A = 1
ld XCPT_HL(iy), a ;
; AF is not preserved (offset 7)
; Save the return address in offset 8
ld l, FRAME_RET(ix) ; HL = Saved return address
ld h, FRAME_RET+1(ix) ;
ld XCPT_PC(iy), l ; Offset 8: PC
ld XCPT_PC+1(iy), h
; Return the value 0
xor a ; HL = return value of zero
ld l, a
ld h, a
pop iy
pop ix
ret
|