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本帖最后由 zc_fly 于 2014-8-19 16:53 编辑
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6 q" F6 t0 t9 F! 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>0 r7 _/ }, G; d, k* V
#include <unistd.h>0 B2 X. F$ d+ e, v6 h( Y& O7 _
#include <sys/mman.h>$ Q: x% `% `9 b5 R) F
#include <sys/types.h>% D3 L% D) c, x- ^" C. X
#include <fcntl.h>
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! U* s% ^/ |, f) `#define SHAER_RAM_BASE_ADDR (0x80000000) * I0 s Q& T( k( n; A
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typedef struct+ g. m# J- a1 L6 @& o
{
' i+ K6 |% J2 x( H unsigned int a;: S' g5 S1 A8 Q5 q7 e& T# G
unsigned int b;1 a/ g+ {6 M6 F, [% C# I/ ~
unsigned int packet_cout;- }7 I4 n& A1 \. h9 j
}RX_MSG_PROTOCOL, *pRX_MSG_PROTOCOL;
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void read_MSG_buffer(pRX_MSG_PROTOCOL pshreRAM);
) D) ^- V, i* Ounsigned int count_copy = 0;
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@+ m8 G C! H* @9 eint main()1 v& ?7 Z+ |- [
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pRX_MSG_PROTOCOL pshreRAM = NULL;
1 R* ?3 t0 E) X# C! _ pshreRAM = (pRX_MSG_PROTOCOL)SHAER_RAM_BASE_ADDR;
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$ `/ Q, M% I" d' B8 }" ? while(1)% F, d& S7 ]& L) k
{
" |# t$ [, U3 ]; @2 a read_MSG_buffer(pshreRAM);) n( d; ~( [* r; V" H
}
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: l# | J5 ]7 L; C1 fvoid read_MSG_buffer(pRX_MSG_PROTOCOL pshreRAM)
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/ _8 a0 m. g; T9 @ RX_MSG_PROTOCOL buf;# R: E: L w9 v
1 n. c- D) f( V( X# g4 y4 o" S buf.a = pshreRAM->a;
N( K5 Q3 C: `: ` buf.b = pshreRAM->b;
3 r6 e4 \3 T$ B* g' U# n$ L. z buf.packet_cout = pshreRAM->packet_cout;2 @, y4 u. h4 O; f7 S P
+ F! \3 a! s. o1 T; O9 w# p if(buf.packet_cout != count_copy)
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printf("a is %d\n", buf.a);
+ b4 ]- A+ s, J) P printf("b is %d\n", buf.b);
* t1 w" E; ^' w& m0 e' X printf("count is %d\n", buf.packet_cout);
: C( v; d' Q% J1 p* _3 g: e6 G count_copy = buf.packet_cout;9 @% Q8 {' [6 q" p
}
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printf("No effective message!");
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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。
. Z/ P& _1 z9 m2 X7 o1 M, s' ~' c/ [. V使用下面代码,对内存使用了mmap函数后:
8 ~# O f8 W; O1 ?6 X7 r#include <stdio.h>) J1 e" ?2 v* G4 v X* B
#include <unistd.h>3 w* n0 |) @ I$ s6 D
#include <sys/mman.h>: I2 t: S: d" e6 `% b
#include <sys/types.h>
' Y" v' [) Q, n2 K5 f( j) M#include <fcntl.h>3 I/ Q2 t' E- h& C
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#define SHAER_RAM_BASE_ADDR (0x80000000)9 Y+ e% n7 x% _- R
#define SHAER_RAM_SIZE (0x20000) : `8 l0 [; ~5 a% I, U, O
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typedef struct3 E0 H/ s5 `1 z. r3 b) O. T
{) N7 n h# h' _$ ]
unsigned int a;- A" y4 d5 x; g
unsigned int b;" _4 K1 i1 u' h. T5 h
unsigned int packet_cout;$ l9 ^' g* k$ G y8 Q+ ]
}RX_MSG_PROTOCOL, *pRX_MSG_PROTOCOL;
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void read_MSG_buffer(int *baseaddr);
( U# C7 d+ R3 v3 `; Bunsigned int count_copy = 0;( E* T0 S( }1 T1 l1 J9 A9 z) U" |
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int main()
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int fd;" q" X& d- N1 O' l& Z+ V2 m" u
int *mem = NULL;
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if((fd = open("/dev/mem", O_RDWR)) <0)1 l4 x0 `; f5 P6 Y/ b
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perror("open error");
: ]) X. n& K, d: n- ^" i4 b return -1;
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, t! r) x: n3 M* |( { mem = mmap((void *)SHAER_RAM_BASE_ADDR, SHAER_RAM_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
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read_MSG_buffer(mem);: U6 u7 S( H9 x" @5 ^$ f
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}
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void read_MSG_buffer(int *baseaddr)0 r& H3 T) [, H4 F
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pRX_MSG_PROTOCOL pshreRAM = NULL;8 D$ _* K$ t5 u) |- Q
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pshreRAM = (pRX_MSG_PROTOCOL)baseaddr; G' y9 u; \5 ]6 }; Y7 N
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if(pshreRAM->packet_cout != count_copy), M9 p, x) F8 |' G
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printf("a is %d\n", pshreRAM->a);
9 n& t5 |* q3 r4 y printf("b is %d\n", pshreRAM->b);& K2 u! u4 g- z& o) l! R- v3 S$ r% D
printf("count is %d\n", pshreRAM->packet_cout);+ V8 u, ?( T9 ~' a- N _8 @
count_copy = pshreRAM->packet_cout;
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& l" Q& I* i6 i# k2 D: T! T else( }9 `; d# _2 T
{
, R! E" U1 J! X printf("No effective message!\n");4 H p$ x6 w" d, X+ S' W0 }
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/ z: ?1 E1 {* j9 v: ^9 d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??? i6 i9 G3 W! y
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