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
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
|
/**************************************************************************
* up_restorecontext.c
*
* Copyright (C) 2007 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <spudmonkey@racsa.co.cr>
*
* 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 Gregory Nutt 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.
*
**************************************************************************/
/**************************************************************************
* Included Files
**************************************************************************/
#include <nuttx/irq.h>
#include "up_internal.h"
/**************************************************************************
* Private Definitions
**************************************************************************/
/**************************************************************************
* Private Types
**************************************************************************/
/**************************************************************************
* Private Function Prototypes
**************************************************************************/
/**************************************************************************
* Global Variables
**************************************************************************/
/**************************************************************************
* Private Variables
**************************************************************************/
/**************************************************************************
* Private Functions
**************************************************************************/
/**************************************************************************
* Public Functions
**************************************************************************/
/**************************************************************************
* Name: up_restoreregisters
*
* Description:
* Restore the saved registers from the context save area. This function
* is called from up_restorecontext (below) and also from interrupt
* handling logic.
*
* Note that this function does not restore:
* a, dptr, ie - these are saved in the stack area
* sp - this can be inferred from g_irqtos or struct xcptontext.nbytes.
*
* Inputs:
* context - the context register array from which to restore the
* register values
*
* Return:
* None
*
**************************************************************************/
void up_restoreregisters(FAR ubyte *regs) _naked
{
_asm
movx a, @dptr
mov b, a
inc dptr
movx a, @dptr
mov r2, a
inc dptr
movx a, @dptr
mov r3, a
inc dptr
movx a, @dptr
mov r4, a
inc dptr
movx a, @dptr
mov r5, a
inc dptr
movx a, @dptr
mov r6, a
inc dptr
movx a, @dptr
mov r7, a
inc dptr
movx a, @dptr
mov r0, a
inc dptr
movx a, @dptr
mov r1, a
inc dptr
movx a, @dptr
mov psw, a
inc dptr
movx a, @dptr
mov _bp, a
ret
_endasm;
}
/**************************************************************************
* Name: up_restorecontext
*
* Description:
* Restore the stack specified in the context structure and return to
* that context
*
* Inputs:
* context - Holds the stack content of the context to return to
*
* Return:
* This function does not return.
*
**************************************************************************/
void up_restorecontext(FAR struct xcptcontext *context) __naked
{
_asm
ar2 = 0x02
ar3 = 0x03
ar4 = 0x04
ar5 = 0x05
ar6 = 0x06
ar7 = 0x07
ar0 = 0x00
ar1 = 0x01
/* Dump the contents of the saved frame before it is copied back
* to memory/registers.
*/
#ifdef CONFIG_SWITCH_FRAME_DUMP
push dpl
push dph
lcall _up_dumpframe
pop dph
pop dpl
#endif
/* Interrupts should be disabled for the following. up_popcontext() will
* set the new interrupt state correctly.
*/
clr ea
/* The following logic will copy the stack from the
* context save structure into IRAM. We cannot use
* the stack in anyway during this copy. Instead,
* we will use registers as follows:
*
* R0 - Holds the working 8-bit IRAM pointer
* R1 - Not used
* R2-3 - Holds the working 16-bit XRAM pointer
* R4 - Holds the working byte count
* R5 - Holds the new stack pointer
* R6-7 - Saved context pointer
*/
/* Fetch r4 = context->nbytes */
movx a, @dptr
mov r4, a
/* Save the new stack pointer in r5 */
add a, #(STACK_BASE-1)
mov r5, a
/* Save r2-3 and r6-r7 = &context->stack */
inc dptr
mov r2, dpl
mov r3, dph
mov r6, dpl
mov r7, dph
/* Set r0 = stack base address */
mov r0, #STACK_BASE
/* Top of the copy loop -- we cannot use the stack
* again until we finish the copy and set the new
* stack pointer (saved in r5)
*/
00001$:
mov a, r4 /* a = bytes left to transfer */
dec r4 /* (for next time through the loop) */
jz 00002$ /* Jump if a = 0 (done) */
/* Fetch the next byte from context->stack */
mov dpl, r2
mov dph, r3
movx a, @dptr
/* Increment the XRAM pointer */
inc dptr
mov r2, dpl
mov r3, dph
/* Save the next byte into IRAM */
mov @r0, a
/* Increment the IRAM pointer */
inc r0
sjmp 00001$
00002$:
/* Set the new stack pointer and recover the
* context->stack pointer.
*/
mov sp, r5
mov dpl, r6
mov dph, r7
/* Dump the stack contents after they have
* been restored to IRAM
*/
#ifdef CONFIG_SWITCH_FRAME_DUMP
push dpl
push dph
lcall _up_dumpstack
pop dph
pop dpl
#endif
/* Get the pointer to the register save area */
mov a, #FRAME_SIZE
add a, dpl
mov dpl, a
clr a
addc a, dph
mov dph, a
/* Restore registers from the register save area */
lcall _up_restoreregisters
/* Restore registers from the new stack */
pop dph
pop dpl
/* Restore the interrupt state per the stored IE value */
pop acc
jb acc.7,00003$
clr ie.7
sjmp 00004$
00003$:
setb ie.7
00004$:
pop acc
ret
_endasm;
}
|