4 * This file is part of BeRTOS.
6 * Bertos is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
20 * As a special exception, you may use this file as part of a free software
21 * library without restriction. Specifically, if other files instantiate
22 * templates or use macros or inline functions from this file, or you compile
23 * this file and link it with other files to produce an executable, this
24 * file does not by itself cause the resulting executable to be covered by
25 * the GNU General Public License. This exception does not however
26 * invalidate any other reasons why the executable file might be covered by
27 * the GNU General Public License.
29 * Copyright 2008 Bernie Innocenti <bernie@codewiz.org>
30 * Copyright 2004, 2005, 2006, 2007, 2008 Develer S.r.l. (http://www.develer.com/)
31 * Copyright 2004 Giovanni Bajo
35 * \brief CPU-specific stack frame handling macros.
37 * These are mainly used by the portable part of the scheduler
38 * to work with the process stack frames.
40 * \author Giovanni Bajo <rasky@develer.com>
41 * \author Bernie Innocenti <bernie@codewiz.org>
42 * \author Stefano Fedrigo <aleph@develer.com>
43 * \author Francesco Sacchi <batt@develer.com>
48 #include <cpu/detect.h>
50 #include "cfg/cfg_arch.h" /* ARCH_EMUL */
51 #include <cfg/compiler.h> /* for uintXX_t */
55 #define CPU_SAVED_REGS_CNT 7
56 #define CPU_STACK_GROWS_UPWARD 0
57 #define CPU_SP_ON_EMPTY_SLOT 0
61 #define CPU_SAVED_REGS_CNT 10
62 #define CPU_STACK_GROWS_UPWARD 0
63 #define CPU_SP_ON_EMPTY_SLOT 0
66 EXTERN_C void asm_proc_entry(void);
68 * Initialization value for registers in stack frame.
69 * For the CPSR register, the initial value is set to:
70 * - All flags (N, Z, C, V) set to 0.
71 * - IRQ and FIQ enabled.
73 * - CPU in Supervisor Mode (SVC).
75 #define CPU_CREATE_NEW_STACK(stack, entry, exit) \
77 /* LR (asm proc_entry trampoline) */ \
78 CPU_PUSH_CALL_FRAME(stack, asm_proc_entry); \
79 /* R11 (Process entry point) DO NOT CHANGE: asm_proc_entry expects \
80 * to find the actual process entry point in R11 */ \
81 CPU_PUSH_CALL_FRAME(stack, entry); \
83 CPU_PUSH_WORD(stack, 0x10101010); \
85 CPU_PUSH_WORD(stack, 0x09090909); \
87 CPU_PUSH_WORD(stack, 0x08080808); \
89 CPU_PUSH_WORD(stack, 0x07070707); \
91 CPU_PUSH_WORD(stack, 0x06060606); \
93 CPU_PUSH_WORD(stack, 0x05050505); \
95 CPU_PUSH_WORD(stack, 0x04040404); \
97 CPU_PUSH_WORD(stack, 0x00000013); \
102 #define CPU_SAVED_REGS_CNT 1
103 #define CPU_STACK_GROWS_UPWARD 0
104 #define CPU_SP_ON_EMPTY_SLOT 1
108 #define CPU_SAVED_REGS_CNT 8
109 #define CPU_STACK_GROWS_UPWARD 1
110 #define CPU_SP_ON_EMPTY_SLOT 0
114 #define CPU_SAVED_REGS_CNT 19
115 #define CPU_STACK_GROWS_UPWARD 0
116 #define CPU_SP_ON_EMPTY_SLOT 1
119 * Initialization value for registers in stack frame.
120 * The register index is not directly corrispondent to CPU
121 * register numbers. Index 0 is the SREG register: the initial
122 * value is all 0 but the interrupt bit (bit 7).
124 #define CPU_REG_INIT_VALUE(reg) (reg == 0 ? 0x80 : 0)
127 #error No CPU_... defined.
130 #ifndef CPU_STACK_GROWS_UPWARD
131 #error CPU_STACK_GROWS_UPWARD should have been defined to either 0 or 1
134 #ifndef CPU_SP_ON_EMPTY_SLOT
135 #error CPU_SP_ON_EMPTY_SLOT should have been defined to either 0 or 1
138 /// Default for macro not defined in the right arch section
139 #ifndef CPU_REG_INIT_VALUE
140 #define CPU_REG_INIT_VALUE(reg) 0
144 * Support stack handling peculiarities of a few CPUs.
146 * Most processors let their stack grow downward and
147 * keep SP pointing at the last pushed value.
149 #if !CPU_STACK_GROWS_UPWARD
150 #if !CPU_SP_ON_EMPTY_SLOT
151 /* Most microprocessors (x86, m68k...) */
152 #define CPU_PUSH_WORD(sp, data) \
153 do { *--(sp) = (data); } while (0)
154 #define CPU_POP_WORD(sp) \
158 #define CPU_PUSH_WORD(sp, data) \
159 do { *(sp)-- = (data); } while (0)
160 #define CPU_POP_WORD(sp) \
164 #else /* CPU_STACK_GROWS_UPWARD */
166 #if !CPU_SP_ON_EMPTY_SLOT
167 /* DSP56K and other weirdos */
168 #define CPU_PUSH_WORD(sp, data) \
169 do { *++(sp) = (cpu_stack_t)(data); } while (0)
170 #define CPU_POP_WORD(sp) \
173 #error I bet you cannot find a CPU like this
180 * DSP56k pushes both PC and SR to the stack in the JSR instruction, but
181 * RTS discards SR while returning (it does not restore it). So we push
182 * 0 to fake the same context.
184 #define CPU_PUSH_CALL_FRAME(sp, func) \
186 CPU_PUSH_WORD((sp), (func)); \
187 CPU_PUSH_WORD((sp), 0x100); \
192 * On AVR, addresses are pushed into the stack as little-endian, while
193 * memory accesses are big-endian (actually, it's a 8-bit CPU, so there is
194 * no natural endianess).
196 #define CPU_PUSH_CALL_FRAME(sp, func) \
198 uint16_t funcaddr = (uint16_t)(func); \
199 CPU_PUSH_WORD((sp), funcaddr); \
200 CPU_PUSH_WORD((sp), funcaddr>>8); \
204 * If the kernel is in idle-spinning, the processor executes:
210 * IRQ_ENABLE is translated in asm as "sei" and IRQ_DISABLE as "cli".
211 * We could define CPU_IDLE to expand to none, so the resulting
217 * But Atmel datasheet states:
218 * "When using the SEI instruction to enable interrupts,
219 * the instruction following SEI will be executed *before*
220 * any pending interrupts", so "cli" is executed before any
221 * pending interrupt with the result that IRQs will *NOT*
223 * To ensure that IRQ will run a NOP is required.
229 #define CPU_PUSH_CALL_FRAME(sp, func) \
231 CPU_PUSH_WORD((sp), (cpu_stack_t)(func)); /* LR -> 8(SP) */ \
232 CPU_PUSH_WORD((sp), 0); /* CR -> 4(SP) */ \
236 #define CPU_PUSH_CALL_FRAME(sp, func) \
237 CPU_PUSH_WORD((sp), (cpu_stack_t)(func))
243 * \brief Invoked by the scheduler to stop the CPU when idle.
245 * This hook can be redefined to put the CPU in low-power mode, or to
246 * profile system load with an external strobe, or to save CPU cycles
247 * in hosted environments such as emulators.
250 #if defined(ARCH_QT) && (ARCH & ARCH_QT)
251 /* This emulator hook should yield the CPU to the host. */
253 void emul_idle(void);
255 #define CPU_IDLE emul_idle()
256 #else /* !ARCH_EMUL */
257 #define CPU_IDLE do { /* nothing */ } while (0)
258 #endif /* !ARCH_EMUL */
259 #endif /* !CPU_IDLE */
262 * Default macro for creating a new Process stack
264 #ifndef CPU_CREATE_NEW_STACK
266 #define CPU_CREATE_NEW_STACK(stack, entry, exit) \
269 /* Initialize process stack frame */ \
270 CPU_PUSH_CALL_FRAME(stack, exit); \
271 CPU_PUSH_CALL_FRAME(stack, entry); \
272 /* Push a clean set of CPU registers for asm_switch_context() */ \
273 for (i = 0; i < CPU_SAVED_REGS_CNT; i++) \
274 CPU_PUSH_WORD(stack, CPU_REG_INIT_VALUE(i)); \
278 #endif /* CPU_ATTR_H */