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本帖最后由 zc_fly 于 2014-8-19 16:53 编辑
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: T, w$ ^! R# v: f+ L1 _# X. OOMAPL138的ARM端对共享区内存进行直接访问,代码如下所示:#include <stdio.h>
* F' ^1 A. O1 z7 s* k A- _* Q. p#include <unistd.h>
; n! W5 ?* w2 \; i* ]#include <sys/mman.h>4 s, \. O8 n1 D
#include <sys/types.h>* Z- u; K" R$ M6 s2 ]' }
#include <fcntl.h>, j0 L# h8 R& Q1 e: f
* _/ W4 S* K7 }6 `#define SHAER_RAM_BASE_ADDR (0x80000000) - X2 F& y/ |; P3 G, a1 W' F
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typedef struct# \& y, h+ H# M& w/ O
{
$ B9 |8 K$ i' L5 Q/ v- S8 A unsigned int a;
3 ~6 x% j2 n: [/ v2 u unsigned int b;( k* l; V1 g |9 Y2 ^
unsigned int packet_cout;3 n; \, I$ ]% Y' D1 j. E& ~
}RX_MSG_PROTOCOL, *pRX_MSG_PROTOCOL;
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void read_MSG_buffer(pRX_MSG_PROTOCOL pshreRAM);
6 o% i4 @2 ` K; d. Runsigned int count_copy = 0;9 J. j, Y; |1 X4 A) f
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int main()' _( P2 x4 B/ C; N8 c. W
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pRX_MSG_PROTOCOL pshreRAM = NULL;( S/ I) w+ R- U. o/ ]
pshreRAM = (pRX_MSG_PROTOCOL)SHAER_RAM_BASE_ADDR;+ G, T7 H7 n# o1 k) V: }! s" W
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while(1)
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( M0 V" U7 m" U read_MSG_buffer(pshreRAM); a# J& o5 `$ ]4 b7 V4 y9 Z \. \
}
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% I+ `0 _! l- S* ]. q$ x. Avoid read_MSG_buffer(pRX_MSG_PROTOCOL pshreRAM)& S$ T; u c! z2 X) f' B7 O2 k$ M
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RX_MSG_PROTOCOL buf;
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buf.a = pshreRAM->a;
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buf.packet_cout = pshreRAM->packet_cout;
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if(buf.packet_cout != count_copy)
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printf("a is %d\n", buf.a);
3 t. `# G- m4 G U; z# Y printf("b is %d\n", buf.b);5 m3 X8 f9 T$ O" V, E" E+ s; g* {9 [
printf("count is %d\n", buf.packet_cout);
: U0 m; g( Y' b. k ]: u count_copy = buf.packet_cout;
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else
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printf("No effective message!");
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* h! `& W0 e5 M; o: @( G {: u0 |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。
! h: y+ k! ~: K; J使用下面代码,对内存使用了mmap函数后:
1 W: Y4 I' K {#include <stdio.h>
8 z) [7 N3 N; x1 I4 g/ }& X; {#include <unistd.h>- s# r; O! N0 u8 z! t, {8 M
#include <sys/mman.h>
/ e+ a! z. y# I. Y! U#include <sys/types.h>9 h+ g f. M6 N# M, v" S# Y7 |
#include <fcntl.h>
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#define SHAER_RAM_BASE_ADDR (0x80000000)
2 W# W+ ?* E* U#define SHAER_RAM_SIZE (0x20000) " f/ I m8 \3 L9 ^
5 |8 N+ C0 K6 g, B; }typedef struct
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unsigned int a;; n* A) S# F5 j
unsigned int b;" P4 E: i4 Q9 V0 n A
unsigned int packet_cout;
* B9 F' X4 ?5 Q& ~: E9 j& P& R}RX_MSG_PROTOCOL, *pRX_MSG_PROTOCOL;9 {0 W7 p! z: g! D4 a; t" g* }8 L8 A
# X8 H; A: w! d3 ovoid read_MSG_buffer(int *baseaddr);2 D; {. G3 U( u* {0 a5 x# p! @
unsigned int count_copy = 0;) \ F$ C4 d3 \
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int main()
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int fd;
+ P* ]& x6 {$ i int *mem = NULL;
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if((fd = open("/dev/mem", O_RDWR)) <0)8 C1 E1 z6 f) ?1 b0 w
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perror("open error");4 E( o, l# b3 z# f- l1 U5 p" `
return -1;
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mem = mmap((void *)SHAER_RAM_BASE_ADDR, SHAER_RAM_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);$ n# ]0 d2 }, ^ b
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while(1)7 Q, I$ ]5 j0 A' f. d
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read_MSG_buffer(mem);
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void read_MSG_buffer(int *baseaddr)
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) u3 w/ t- C- V: o pRX_MSG_PROTOCOL pshreRAM = NULL;
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pshreRAM = (pRX_MSG_PROTOCOL)baseaddr;
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if(pshreRAM->packet_cout != count_copy)% G8 H9 z1 a# b. q4 f# Q0 a
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printf("a is %d\n", pshreRAM->a);
2 g. M$ f" Y4 p( B# S printf("b is %d\n", pshreRAM->b);5 u" P4 L0 x3 U: k, T
printf("count is %d\n", pshreRAM->packet_cout);7 \+ F; l' R. s/ a" q9 s
count_copy = pshreRAM->packet_cout;
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printf("No effective message!\n");( n9 t* a1 c. S
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$ d! \0 N' h, Z3 X4 H# a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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