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 2
57 #define CPU_SAVED_REGS_CNT 8
61 #define CPU_STACK_GROWS_UPWARD 0
62 #define CPU_SP_ON_EMPTY_SLOT 0
66 #define CPU_SAVED_REGS_CNT 8
67 #define CPU_STACK_GROWS_UPWARD 0
68 #define CPU_SP_ON_EMPTY_SLOT 0
72 #define CPU_SAVED_REGS_CNT 1
73 #define CPU_STACK_GROWS_UPWARD 0
74 #define CPU_SP_ON_EMPTY_SLOT 1
78 #define CPU_SAVED_REGS_CNT 8
79 #define CPU_STACK_GROWS_UPWARD 1
80 #define CPU_SP_ON_EMPTY_SLOT 0
84 #define CPU_SAVED_REGS_CNT 18
85 #define CPU_STACK_GROWS_UPWARD 0
86 #define CPU_SP_ON_EMPTY_SLOT 1
89 #error No CPU_... defined.
92 #ifndef CPU_STACK_GROWS_UPWARD
93 #error CPU_STACK_GROWS_UPWARD should have been defined to either 0 or 1
96 #ifndef CPU_SP_ON_EMPTY_SLOT
97 #error CPU_SP_ON_EMPTY_SLOT should have been defined to either 0 or 1
100 /// Default for macro not defined in the right arch section
101 #ifndef CPU_REG_INIT_VALUE
102 #define CPU_REG_INIT_VALUE(reg) (reg)
106 * Support stack handling peculiarities of a few CPUs.
108 * Most processors let their stack grow downward and
109 * keep SP pointing at the last pushed value.
111 #if !CPU_STACK_GROWS_UPWARD
112 #if !CPU_SP_ON_EMPTY_SLOT
113 /* Most microprocessors (x86, m68k...) */
114 #define CPU_PUSH_WORD(sp, data) \
115 do { *--(sp) = (data); } while (0)
116 #define CPU_POP_WORD(sp) \
120 #define CPU_PUSH_WORD(sp, data) \
121 do { *(sp)-- = (data); } while (0)
122 #define CPU_POP_WORD(sp) \
126 #else /* CPU_STACK_GROWS_UPWARD */
128 #if !CPU_SP_ON_EMPTY_SLOT
129 /* DSP56K and other weirdos */
130 #define CPU_PUSH_WORD(sp, data) \
131 do { *++(sp) = (cpu_stack_t)(data); } while (0)
132 #define CPU_POP_WORD(sp) \
135 #error I bet you cannot find a CPU like this
142 * DSP56k pushes both PC and SR to the stack in the JSR instruction, but
143 * RTS discards SR while returning (it does not restore it). So we push
144 * 0 to fake the same context.
146 #define CPU_PUSH_CALL_FRAME(sp, func) \
148 CPU_PUSH_WORD((sp), (func)); \
149 CPU_PUSH_WORD((sp), 0x100); \
154 * On AVR, addresses are pushed into the stack as little-endian, while
155 * memory accesses are big-endian (actually, it's a 8-bit CPU, so there is
156 * no natural endianess).
158 #define CPU_PUSH_CALL_FRAME(sp, func) \
160 uint16_t funcaddr = (uint16_t)(func); \
161 CPU_PUSH_WORD((sp), funcaddr); \
162 CPU_PUSH_WORD((sp), funcaddr>>8); \
166 * If the kernel is in idle-spinning, the processor executes:
172 * IRQ_ENABLE is translated in asm as "sei" and IRQ_DISABLE as "cli".
173 * We could define CPU_IDLE to expand to none, so the resulting
179 * But Atmel datasheet states:
180 * "When using the SEI instruction to enable interrupts,
181 * the instruction following SEI will be executed *before*
182 * any pending interrupts", so "cli" is executed before any
183 * pending interrupt with the result that IRQs will *NOT*
185 * To ensure that IRQ will run a NOP is required.
191 #define CPU_PUSH_CALL_FRAME(sp, func) \
193 CPU_PUSH_WORD((sp), (cpu_stack_t)(func)); /* LR -> 8(SP) */ \
194 CPU_PUSH_WORD((sp), 0); /* CR -> 4(SP) */ \
198 #define CPU_PUSH_CALL_FRAME(sp, func) \
199 CPU_PUSH_WORD((sp), (cpu_stack_t)(func))
205 * \brief Invoked by the scheduler to stop the CPU when idle.
207 * This hook can be redefined to put the CPU in low-power mode, or to
208 * profile system load with an external strobe, or to save CPU cycles
209 * in hosted environments such as emulators.
212 #define CPU_IDLE PAUSE
213 #endif /* !CPU_IDLE */
216 * Default macro for creating a new Process stack
218 #ifndef CPU_CREATE_NEW_STACK
220 #define CPU_CREATE_NEW_STACK(stack) \
223 /* Initialize process stack frame */ \
224 CPU_PUSH_CALL_FRAME(stack, proc_entry); \
225 /* Push a clean set of CPU registers for asm_switch_context() */ \
226 for (i = 0; i < CPU_SAVED_REGS_CNT; i++) \
227 CPU_PUSH_WORD(stack, CPU_REG_INIT_VALUE(i)); \
231 #endif /* CPU_ATTR_H */