GNU ARM汇编(五)中断汇编之嵌套中断处理

在上篇《GNU ARM汇编--(四)中断汇编之非嵌套中断处理》中分析了最简单的中断处理的写法,再看TQ2440启动代码中的中断向量表的写法就一目了然了.今天抽时间对嵌套中断处理的学习做下整理.

嵌套中断处理的核心代码如下:

;/*; *  ____________________________________________________________________; * ; *  Copyright (c) 2004, Andrew N. Sloss, Chris Wright and Dominic Symes; *  All rights reserved.; *  ____________________________________________________________________; * ; *  NON-COMMERCIAL USE License; *  ; *  Redistribution and use in source and binary forms, with or without ; *  modification, are permitted provided that the following conditions ; *  are met: ; *  ; *  1. For NON-COMMERCIAL USE only.; * ; *  2. Redistributions of source code must retain the above copyright ; *     notice, this list of conditions and the following disclaimer. ; * ; *  3. 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. ; * ; *  4. All advertising materials mentioning features or use of this ; *     software must display the following acknowledgement:; * ; *     This product includes software developed by Andrew N. Sloss,; *     Chris Wright and Dominic Symes. ; * ; *   THIS SOFTWARE IS PROVIDED BY THE 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 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. ; * ; *  If you have questions about this license or would like a different; *  license please email :; * ; *  andrew@sloss.net; * ; * ; */;/*; *; *  Module       : nih9_9.s; *  Descriptions : Nested Interrupt Handler; *  Example      : 9.9; *  OS           : generic; *  Platform     : generic; *  History      :; *; *  31th December 2003; *  - added header; *; */EXPORT nestedInterruptHandlerMaskmd     EQU 0x1f                     ; processor mode maskSVC32md    EQU 0x13                     ; SVC modeI_Bit      EQU 0x80                     ; IRQ bit FRAME_R0   EQU 0x00			FRAME_R1   EQU FRAME_R0+4FRAME_R2   EQU FRAME_R1+4FRAME_R3   EQU FRAME_R2+4FRAME_R4   EQU FRAME_R3+4FRAME_R5   EQU FRAME_R4+4FRAME_R6   EQU FRAME_R5+4FRAME_R7   EQU FRAME_R6+4FRAME_R8   EQU FRAME_R7+4FRAME_R9   EQU FRAME_R8+4FRAME_R10  EQU FRAME_R9+4FRAME_R11  EQU FRAME_R10+4FRAME_R12  EQU FRAME_R11+4FRAME_PSR  EQU FRAME_R12+4FRAME_LR   EQU FRAME_PSR+4FRAME_PC   EQU FRAME_LR+4FRAME_SIZE EQU FRAME_PC+4AREA nih9_9,CODE,readonlynestedInterruptHandler ; instruction       state : comment		SUB     r14,r14,#4                 ; 2 :STMDB   r13!,{r0-r3,r12,r14}       ; 2 : save context; BL      read_RescheduleFlag        ; 3 : more processingCMP     r0,#0                      ; 3 : if processing?LDMNEIA r13!,{r0-r3,r12,pc}^       ; 4 :   then return MRS     r2,SPSR                    ; 5 : copy SPSR_irqMOV     r0,r13                     ; 5 : copy r13_irqADD     r13,r13,#6*4               ; 5 : reset stackMRS     r1,CPSR                    ; 6 : copy CPSRBIC     r1,r1,#Maskmd              ; 6 :ORR     r1,r1,#SVC32md             ; 6 :MSR     CPSR_c,r1                  ; 6 : change SVC modeSUB     r13,r13,#FRAME_SIZE-FRAME_R4 ; 7 : make stack space STMIA   r13,{r4-r11}               ; 7 : save r4-r11LDMIA   r0,{r4-r9}                 ; 7 : r4-r9 IRQ stack BIC     r1,r1,#I_Bit               ; 8 : MSR     CPSR_c,r1                  ; 8 : enable intSTMDB   r13!,{r4-r7}               ; 9 : save r4-r7 SVCSTR     r2,[r13,#FRAME_PSR]        ; 9 : save PSRSTR     r8,[r13,#FRAME_R12]        ; 9 : save r12STR     r9,[r13,#FRAME_PC]         ; 9 : save pc      STR     r14,[r13,#FRAME_LR]        ; 9 : save lr; LDMIA   r13!,{r0-r12,r14}          ; 11 : restore contextMSR     SPSR_cxsf,r14              ; 11 : restore SPSRLDMIA   r13!,{r14,pc}^             ; 11 : returnread_RescheduleFlag; MOV     r0,#0                      ; more processing MOV     pc,r14                     ; returnEND