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本帖最后由 zc_fly 于 2014-8-19 16:53 编辑
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OMAPL138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 l9 X3 m: @, h4 q% G2 G- h
#include <unistd.h>$ M5 B4 P. K7 ~& V2 s7 b2 O2 n
#include <sys/mman.h>6 Q8 D# ~4 i* E9 l0 ~# q
#include <sys/types.h>
, l6 z: z. f) _' A% W6 E x4 n#include <fcntl.h>7 t! X! h/ z3 D! H; P# M$ A
" T% n8 ~" n8 q7 o#define SHAER_RAM_BASE_ADDR (0x80000000) " h0 ]) D* [, z/ j( b; [/ b$ x
( h5 d: [/ W; s1 x+ Btypedef struct: x& Y& S6 Q- E& E* Y3 s' @" R
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unsigned int a;) _; B5 t+ ?. ]
unsigned int b;. u8 Z' r9 `( L, x9 f- H' W
unsigned int packet_cout;8 W# Q& H! v8 K: t) V
}RX_MSG_PROTOCOL, *pRX_MSG_PROTOCOL;
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void read_MSG_buffer(pRX_MSG_PROTOCOL pshreRAM);" M, q z0 f( k- F
unsigned int count_copy = 0;
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/ _( M, E9 ]3 L/ t/ v( Gint main()
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pRX_MSG_PROTOCOL pshreRAM = NULL;
3 J0 d, ]/ J+ ^, K6 `7 ^$ q 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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9 X1 c% h/ U+ m1 C8 K3 svoid read_MSG_buffer(pRX_MSG_PROTOCOL pshreRAM)
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/ S( ?0 o8 T2 H% \ RX_MSG_PROTOCOL buf;
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* X3 |2 D5 y( ^& S. p buf.a = pshreRAM->a;
m, z5 g, ?4 p buf.b = pshreRAM->b;7 Z* }2 c' u9 ^* J& N; U
buf.packet_cout = pshreRAM->packet_cout;
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8 a; \! A5 [ A/ f if(buf.packet_cout != count_copy); l7 a) s; a+ o# t+ N0 D
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printf("a is %d\n", buf.a);
& ?2 {( s8 {# c5 |( ^& s; I5 m n printf("b is %d\n", buf.b);, B6 l& F4 f' }9 r( |& A
printf("count is %d\n", buf.packet_cout);
5 B' D7 C3 J1 s* O! m9 G. |/ M count_copy = buf.packet_cout;
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else+ n3 G2 T3 l4 Q' l- `: f; p
{
5 d7 H9 w4 n8 J- Y: |" r/ h printf("No effective message!");/ x6 K, \ ]! @) F
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}
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4 `$ Q8 C& U# a- m- x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。, i, t8 P1 N; }! r' @8 k
使用下面代码,对内存使用了mmap函数后:
3 \- O- F% q% E: W T2 O6 I#include <stdio.h>
) C% J0 k1 x: |) P#include <unistd.h>
/ G8 }. W6 U% D8 L; o& ?2 r#include <sys/mman.h>
5 I0 J+ V6 l% w3 r% z, S" y4 u#include <sys/types.h>" @, y2 i6 ^* [1 ^4 q# N$ ]. i9 ^
#include <fcntl.h>, w7 h& s( Q( \$ ^4 j
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#define SHAER_RAM_BASE_ADDR (0x80000000)
' l L. S% b4 z9 i/ B#define SHAER_RAM_SIZE (0x20000) " P6 ^+ D" \! p7 z
) | a* h) _: X4 l8 [2 S$ Qtypedef struct
8 g7 [ L) N+ ]2 ^( H{
8 Y5 c' E0 D7 h6 O1 _$ r unsigned int a;( b- e, }; C& ]1 }
unsigned int b;
! `4 k! i" B& Y/ w2 c8 [' I unsigned int packet_cout;
$ c/ i. ~( I" j- Y}RX_MSG_PROTOCOL, *pRX_MSG_PROTOCOL;' D. {* O, G' T' c0 G4 J
8 V/ C3 ?' L% kvoid read_MSG_buffer(int *baseaddr);
0 D& ^# f5 m3 Q- vunsigned int count_copy = 0;
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int main(): m* N$ h6 y1 h9 L5 d5 F! w0 ~. c. _
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int fd;
7 M( o* B" d s, H+ _/ p5 x int *mem = NULL;
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if((fd = open("/dev/mem", O_RDWR)) <0)
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! A F. u& o- c perror("open error");: ~! k$ o# o5 ^: c5 z# O" d
return -1;" ~( h3 ^/ t) z* x" k. ^9 f# @ g
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3 m: o: z; K; [" K4 K mem = mmap((void *)SHAER_RAM_BASE_ADDR, SHAER_RAM_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
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/ l1 i9 s' C" y1 ~& ^' ?# A, @2 W while(1)) d W4 b6 @9 q" X! x8 A
{
4 L; W7 c# z$ y read_MSG_buffer(mem);$ l% l- I4 O8 V5 S
}
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0 T2 k1 `+ ~8 D, G/ F1 f* O, Uvoid read_MSG_buffer(int *baseaddr)
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pRX_MSG_PROTOCOL pshreRAM = NULL;' @, |' p$ T$ _- U7 e! [2 X
8 u* k; d9 W2 ]5 k. X; @* o pshreRAM = (pRX_MSG_PROTOCOL)baseaddr;7 y4 P( P0 M! q8 l; _
8 Z" o/ [. h1 V# ^& e9 `2 Z* z1 M if(pshreRAM->packet_cout != count_copy)
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printf("a is %d\n", pshreRAM->a);1 ]: X, s$ u e
printf("b is %d\n", pshreRAM->b);2 g" a9 P5 y: r; l- W' W' ^
printf("count is %d\n", pshreRAM->packet_cout);) {( S) u7 `/ J1 e, I6 |
count_copy = pshreRAM->packet_cout;
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else q. g4 T3 z0 j+ \5 E( b9 T
{
) K& Y& c% n4 M$ [+ D printf("No effective message!\n");
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" y2 [5 K0 E0 Z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???* \* V! l1 A( X: W* e
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