关于int全区变量读写的原子性

标签：atomic   原子操作   全局变量赋值保护   临界区   

typedef struct {
    char c1;
    char c2;
// atomic_t i1;
    int i1;
} str_t;
volatile str_t Gstr ;
int main(void)
{
    Gstr.c1 = 1;
    Gstr.c2 = 2;
    Gstr.i1 = 0x12345678;
    while (1);
    return 0;
}

int main(void)
{
    8000: e52db004 push {fp} ; (str fp, [sp, #-4]!)
    8004: e28db000 add fp, sp, #0
    Gstr.c1 = 1;
    8008: e59f1030 ldr r1, [pc, #48] ; 8040 <main+0x40>
    800c: e3a03001 mov r3, #1
    8010: e1a02003 mov r2, r3
    8014: e1a03001 mov r3, r1
    8018: e5c32000 strb r2, [r3]
    Gstr.c2 = 2;
    801c: e59f101c ldr r1, [pc, #28] ; 8040 <main+0x40>
    8020: e3a03002 mov r3, #2
    8024: e1a02003 mov r2, r3
    8028: e1a03001 mov r3, r1
    802c: e5c32001 strb r2, [r3, #1]
    Gstr.i1 = 0x12345678;
    8030: e59f3008 ldr r3, [pc, #8] ; 8040 <main+0x40>
    8034: e59f2008 ldr r2, [pc, #8] ; 8044 <main+0x44>
    8038: e5832004 str r2, [r3, #4]
    while (1);
    803c: eafffffe b 803c <main+0x3c>
    8040: 00010060 .word 0x00010060
    8044: 12345678 .word 0x12345678

</pre><pre name="code" class="cpp">typedef struct {
    char c1;
    int i1;
} __attribute__((__packed__)) str_t;

volatile str_t Gstr ;

int main(void)
{
    Gstr.c1 = 1;
    Gstr.i1 = 0x12345678;
    while (1);
    return 0;
}
    Gstr.i1 = 0x12345678;
    801c:	e59f3024 ldr	r3, [pc, #36]	; 8048 <main+0x48>
    8020:	e5932000 ldr	r2, [r3]
    8024:	e20210ff and	r1, r2, #255	; 0xff
    8028:	e59f201c ldr	r2, [pc, #28]	; 804c <main+0x4c>
    802c:	e1812002 orr	r2, r1, r2
    8030:	e5832000 str	r2, [r3]
    8034:	e5932004 ldr	r2, [r3, #4]
    8038:	e3c220ff bic	r2, r2, #255	; 0xff
    803c:	e3822012 orr	r2, r2, #18
    8040:	e5832004 str	r2, [r3, #4]
    while (1);
    8044:	eafffffe b	8044 <main+0x44>
    8048:	00010068 .word	0x00010068
    804c:	34567800 .word	0x34567800

typedef struct {
    char c1;
    int i1;
} __attribute__((__packed__)) str_t;
volatile str_t Gstr ;
int rd;
int main(void)
{
    rd = Gstr.i1;
    while (1);
    return 0;
}
    rd = Gstr.i1;
    8008: e59f3024 ldr r3, [pc, #36] ; 8034 <main+0x34>
    800c: e5932000 ldr r2, [r3]
    8010: e1a02422 lsr r2, r2, #8
    8014: e5933004 ldr r3, [r3, #4]
    8018: e20330ff and r3, r3, #255 ; 0xff
    801c: e1a03c03 lsl r3, r3, #24
    8020: e1833002 orr r3, r3, r2
    8024: e1a02003 mov r2, r3
    8028: e59f3008 ldr r3, [pc, #8] ; 8038 <main+0x38>
    802c: e5832000 str r2, [r3]
    while (1);
    8030: eafffffe b 8030 <main+0x30>
    8034: 00010054 .word 0x00010054
    8038: 0001005c .word 0x0001005c

关于int全区变量读写的原子性

标签：atomic   原子操作   全局变量赋值保护   临界区   

原文地址：http://blog.csdn.net/huanghui167/article/details/41346113