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 * Initialization value for registers in stack frame.
67 * The register index is not directly corrispondent to CPU
68 * register numbers, but is related to how are pushed to
69 * stack (\see asm_switch_context).
70 * Index (CPU_SAVED_REGS_CNT - 1) is the CPSR register,
71 * the initial value is set to:
72 * - All flags (N, Z, C, V) set to 0.
73 * - IRQ and FIQ enabled.
75 * - CPU in Supervisor Mode (SVC).
77 #define CPU_REG_INIT_VALUE(reg) \
81 else if(reg == (CPU_SAVED_REGS_CNT - 1)) \
88 #define CPU_SAVED_REGS_CNT 1
89 #define CPU_STACK_GROWS_UPWARD 0
90 #define CPU_SP_ON_EMPTY_SLOT 1
94 #define CPU_SAVED_REGS_CNT 8
95 #define CPU_STACK_GROWS_UPWARD 1
96 #define CPU_SP_ON_EMPTY_SLOT 0
100 #define CPU_SAVED_REGS_CNT 19
101 #define CPU_STACK_GROWS_UPWARD 0
102 #define CPU_SP_ON_EMPTY_SLOT 1
105 * Initialization value for registers in stack frame.
106 * The register index is not directly corrispondent to CPU
107 * register numbers. Index 0 is the SREG register: the initial
108 * value is all 0 but the interrupt bit (bit 7).
110 #define CPU_REG_INIT_VALUE(reg) (reg == 0 ? 0x80 : 0)
113 #error No CPU_... defined.
116 #ifndef CPU_STACK_GROWS_UPWARD
117 #error CPU_STACK_GROWS_UPWARD should have been defined to either 0 or 1
120 #ifndef CPU_SP_ON_EMPTY_SLOT
121 #error CPU_SP_ON_EMPTY_SLOT should have been defined to either 0 or 1
124 /// Default for macro not defined in the right arch section
125 #ifndef CPU_REG_INIT_VALUE
126 #define CPU_REG_INIT_VALUE(reg) 0
130 * Support stack handling peculiarities of a few CPUs.
132 * Most processors let their stack grow downward and
133 * keep SP pointing at the last pushed value.
135 #if !CPU_STACK_GROWS_UPWARD
136 #if !CPU_SP_ON_EMPTY_SLOT
137 /* Most microprocessors (x86, m68k...) */
138 #define CPU_PUSH_WORD(sp, data) \
139 do { *--(sp) = (data); } while (0)
140 #define CPU_POP_WORD(sp) \
144 #define CPU_PUSH_WORD(sp, data) \
145 do { *(sp)-- = (data); } while (0)
146 #define CPU_POP_WORD(sp) \
150 #else /* CPU_STACK_GROWS_UPWARD */
152 #if !CPU_SP_ON_EMPTY_SLOT
153 /* DSP56K and other weirdos */
154 #define CPU_PUSH_WORD(sp, data) \
155 do { *++(sp) = (cpu_stack_t)(data); } while (0)
156 #define CPU_POP_WORD(sp) \
159 #error I bet you cannot find a CPU like this
166 * DSP56k pushes both PC and SR to the stack in the JSR instruction, but
167 * RTS discards SR while returning (it does not restore it). So we push
168 * 0 to fake the same context.
170 #define CPU_PUSH_CALL_FRAME(sp, func) \
172 CPU_PUSH_WORD((sp), (func)); \
173 CPU_PUSH_WORD((sp), 0x100); \
178 * On AVR, addresses are pushed into the stack as little-endian, while
179 * memory accesses are big-endian (actually, it's a 8-bit CPU, so there is
180 * no natural endianess).
182 #define CPU_PUSH_CALL_FRAME(sp, func) \
184 uint16_t funcaddr = (uint16_t)(func); \
185 CPU_PUSH_WORD((sp), funcaddr); \
186 CPU_PUSH_WORD((sp), funcaddr>>8); \
190 * If the kernel is in idle-spinning, the processor executes:
196 * IRQ_ENABLE is translated in asm as "sei" and IRQ_DISABLE as "cli".
197 * We could define CPU_IDLE to expand to none, so the resulting
203 * But Atmel datasheet states:
204 * "When using the SEI instruction to enable interrupts,
205 * the instruction following SEI will be executed *before*
206 * any pending interrupts", so "cli" is executed before any
207 * pending interrupt with the result that IRQs will *NOT*
209 * To ensure that IRQ will run a NOP is required.
215 #define CPU_PUSH_CALL_FRAME(sp, func) \
217 CPU_PUSH_WORD((sp), (cpu_stack_t)(func)); /* LR -> 8(SP) */ \
218 CPU_PUSH_WORD((sp), 0); /* CR -> 4(SP) */ \
222 #define CPU_PUSH_CALL_FRAME(sp, func) \
223 CPU_PUSH_WORD((sp), (cpu_stack_t)(func))
229 * \brief Invoked by the scheduler to stop the CPU when idle.
231 * This hook can be redefined to put the CPU in low-power mode, or to
232 * profile system load with an external strobe, or to save CPU cycles
233 * in hosted environments such as emulators.
236 #if defined(ARCH_QT) && (ARCH & ARCH_QT)
237 /* This emulator hook should yield the CPU to the host. */
239 void emul_idle(void);
241 #define CPU_IDLE emul_idle()
242 #else /* !ARCH_EMUL */
243 #define CPU_IDLE do { /* nothing */ } while (0)
244 #endif /* !ARCH_EMUL */
245 #endif /* !CPU_IDLE */
247 #endif /* CPU_ATTR_H */