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本帖最后由 zc_fly 于 2014-8-19 16:53 编辑 2 A1 N ]. k* }" ^- H9 R
! M) k- W9 F! ~& cOMAPL138的ARM端对共享区内存进行直接访问,代码如下所示:#include <stdio.h>4 b5 H8 M V8 q' L" l% Z- _) x
#include <unistd.h>
4 m. g7 P# g. j l7 ]#include <sys/mman.h>; m2 e$ {8 O; ]
#include <sys/types.h># r6 N& K7 z8 `6 m, F6 y7 {$ h/ ]
#include <fcntl.h>* D( p6 f/ V9 u3 I5 a9 J
) s$ j4 B+ J1 @) {* A( e2 \#define SHAER_RAM_BASE_ADDR (0x80000000)
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typedef struct n6 Q& t7 I0 U) u) i
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unsigned int a;" m& S2 ?* j9 G% g
unsigned int b;" ]9 t# I, K4 c. Y
unsigned int packet_cout;6 z6 g3 Y/ ]* z1 R% R
}RX_MSG_PROTOCOL, *pRX_MSG_PROTOCOL;
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" y2 R5 m/ q/ |, M' Y3 Yvoid read_MSG_buffer(pRX_MSG_PROTOCOL pshreRAM);
3 ^3 U" A2 r4 @. G; Xunsigned int count_copy = 0;9 C0 Y8 x9 v1 G/ q; g
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0 k8 w! b- c( v/ @int main()3 e7 t A5 d( D$ U! {8 K
{
! y7 p x. i5 E. |% w0 c pRX_MSG_PROTOCOL pshreRAM = NULL;3 ]2 @' A+ S6 |" b5 c: D9 r/ R
pshreRAM = (pRX_MSG_PROTOCOL)SHAER_RAM_BASE_ADDR;
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while(1)
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read_MSG_buffer(pshreRAM);
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void read_MSG_buffer(pRX_MSG_PROTOCOL pshreRAM)7 I- t/ O3 Y; c% q0 j3 J
{
! t4 W. h0 c) U. D* m- X RX_MSG_PROTOCOL buf;
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buf.a = pshreRAM->a;4 M& n: n, U2 F) v( R" f5 e! c7 W
buf.b = pshreRAM->b;
" F' N9 O& }/ z( j1 h% y buf.packet_cout = pshreRAM->packet_cout;
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F$ ^! `% b, [9 C8 U8 O# s- o if(buf.packet_cout != count_copy)
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' M' a+ w* ]7 z; u% h$ m" X% w printf("a is %d\n", buf.a);7 ?3 q' N. {+ c) O H- T: z h
printf("b is %d\n", buf.b);
7 X6 L1 @5 d6 @: I3 O, B) ]+ l& ]3 j5 u% G printf("count is %d\n", buf.packet_cout);% D9 C) k7 d# d4 E6 ^
count_copy = buf.packet_cout;
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printf("No effective message!");7 O5 ~% I$ W* H9 j
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& l) K4 {8 h9 X6 a6 |& j% `但是出现segmentation fault的问题,这是什么原因啊???我在DSP端烧写了一段小程序,向共享区0x80000000位置写入数据,用CCS 测试发现写入成功。
/ Y( X0 [) u. P: ]0 L; H使用下面代码,对内存使用了mmap函数后:+ ?& r4 Q7 G7 _- r' o' K
#include <stdio.h>
- E0 m2 n+ `+ I% }* r- N2 j6 o#include <unistd.h>
) w) e" h% S% Z( i#include <sys/mman.h>+ ^( w) N! j* p$ b, A7 C
#include <sys/types.h>
; ?' V4 K, w- r#include <fcntl.h>. _: K( c0 S) z4 u, ^
* i! j. ?; ~' a; n7 o, p#define SHAER_RAM_BASE_ADDR (0x80000000)6 a$ Y' ^4 a( P6 _9 w `
#define SHAER_RAM_SIZE (0x20000)
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typedef struct
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unsigned int a;
( ~/ m0 t" c+ j7 L; `' E unsigned int b;$ O/ F& o q9 E, ?, i
unsigned int packet_cout;" N# F9 X( h R' c( d
}RX_MSG_PROTOCOL, *pRX_MSG_PROTOCOL;
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void read_MSG_buffer(int *baseaddr);# F5 l% V8 J2 b6 z* U
unsigned int count_copy = 0;/ z0 X1 Q1 c* l+ h. E2 O. K5 j
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int main()" I) s7 _# r- y5 S0 u
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int fd;
1 c& I! X. Y5 b5 @. y$ d( W int *mem = NULL;
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; D' |( `6 e) }% P: b, S9 t9 n if((fd = open("/dev/mem", O_RDWR)) <0)
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" \" r$ z$ H: }# G) d ]8 p @ perror("open error");3 Y3 z' [, ^; \( d* S F
return -1;) R* x* K) B4 P
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mem = mmap((void *)SHAER_RAM_BASE_ADDR, SHAER_RAM_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);* b2 p0 r5 C" S6 z6 [
* n2 g4 P0 f, w7 O, A0 b while(1)
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9 k4 ]7 Y. N! b' l4 A" { read_MSG_buffer(mem);* q& r4 K6 ^0 p9 \
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}
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" t3 L- r7 p6 _void read_MSG_buffer(int *baseaddr)
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pRX_MSG_PROTOCOL pshreRAM = NULL;: M+ X( k$ C2 B% Q2 {1 z! a
8 P+ P# H. c5 O3 w pshreRAM = (pRX_MSG_PROTOCOL)baseaddr;2 ?" P! T5 ^8 e- X6 L* c' j/ Y F
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if(pshreRAM->packet_cout != count_copy)
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printf("a is %d\n", pshreRAM->a);! j% `% a! R* N/ A/ T. V
printf("b is %d\n", pshreRAM->b);
8 ]; `' B. g- t printf("count is %d\n", pshreRAM->packet_cout);
0 ?! Q. o7 f2 k- l count_copy = pshreRAM->packet_cout;
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else- Z/ C3 g- S4 M
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printf("No effective message!\n");
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}
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9 @6 N8 o/ v" M0 n; Z- p$ S" a5 U% X没有出现segmentation fault这个错误,但是读出来的数据均为0。这该怎样解决啊???主要问题还是在Linux系统下,OMAPL138是否可以直接访问映射地址???该怎样实现???
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