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本帖最后由 zc_fly 于 2014-8-19 16:53 编辑 8 E% P& e" N& G$ C" n* b' z. N$ B
: s- k5 q+ M) u6 r3 |8 JOMAPL138的ARM端对共享区内存进行直接访问,代码如下所示:#include <stdio.h>
& k+ Q0 s! N5 v0 R* e! I#include <unistd.h>
( s. U9 w; o( G: U% a) Q4 w; `$ _#include <sys/mman.h>$ H6 H2 A( g( D( E) M
#include <sys/types.h>
7 F+ N$ s3 I Y! O& t% w2 `) ?#include <fcntl.h>0 y L% H* i7 [' C
9 \$ I1 H2 j t4 b#define SHAER_RAM_BASE_ADDR (0x80000000) 9 Y: i" d' q6 b- V$ R9 K! z3 p
k9 U) Q+ e2 D% gtypedef struct
# C6 {- I& ?& ]( I7 G0 u. K) h{
4 w# t0 x$ g& x/ @) q9 d unsigned int a;4 G( K0 W2 ^# l2 @0 }
unsigned int b;" T% ~2 O U L# |, N
unsigned int packet_cout;
, y% p% ^3 p- L9 k}RX_MSG_PROTOCOL, *pRX_MSG_PROTOCOL;: c1 | x+ x8 _- A" y
% |# i* y9 H8 A$ k# mvoid read_MSG_buffer(pRX_MSG_PROTOCOL pshreRAM);
5 q' S: A3 N r$ Uunsigned int count_copy = 0;. d. I8 A- P& D; s0 ? I, m
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, O5 R0 {# [& V0 \5 Qint main()$ N9 t1 t" d( Q$ \
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pRX_MSG_PROTOCOL pshreRAM = NULL;
: t* B, P5 G- C2 M( }. h' Y pshreRAM = (pRX_MSG_PROTOCOL)SHAER_RAM_BASE_ADDR;
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# w! ~: ?# ?& y" G# U X: ^7 H6 F while(1)5 j3 v" C( b2 O7 H2 [* }
{
0 X- Z+ |$ [, d7 f: \ read_MSG_buffer(pshreRAM);2 A3 |( { o" d9 Y) ^$ x
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void read_MSG_buffer(pRX_MSG_PROTOCOL pshreRAM)
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RX_MSG_PROTOCOL buf;) ?: s# h2 `+ [0 P; y4 i
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buf.a = pshreRAM->a;
+ u( b! X1 Q! f j; K+ W buf.b = pshreRAM->b;
- i: k L o1 C. g. a buf.packet_cout = pshreRAM->packet_cout;* _/ S% r( G; w
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if(buf.packet_cout != count_copy)! Z( b) ?# h4 v% _
{
, E) x( _* P! k$ c( @/ m printf("a is %d\n", buf.a);; p% j3 h& P/ r4 e
printf("b is %d\n", buf.b);% N( f* ^+ h0 X/ r7 }3 Y
printf("count is %d\n", buf.packet_cout);8 Q: S7 I7 ?5 U2 [4 C' v0 k
count_copy = buf.packet_cout;$ }% r8 D" t$ y; }) I* R
}
& x/ G; g) v& ? else
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printf("No effective message!");
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5 K: {4 d4 [, a. ]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。
* B6 u+ s( a5 R& p( N" |8 \# ?' Z使用下面代码,对内存使用了mmap函数后:
5 p5 [# J& Z* F+ f" s/ Y8 H1 A4 r$ i" @- H#include <stdio.h>0 m8 J2 M" v8 \& |2 O- e9 k
#include <unistd.h>2 A4 H1 U0 M4 ^5 ]+ G
#include <sys/mman.h>
: Z6 p1 E% [0 Y- z1 S, U4 r#include <sys/types.h>$ K1 A6 r) H3 G- d: W. K) B; U
#include <fcntl.h>
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" r$ K+ ~* W+ |) `: |: s#define SHAER_RAM_BASE_ADDR (0x80000000)
$ W7 _( P; ~' h9 c, }2 W3 ~0 w( i#define SHAER_RAM_SIZE (0x20000) 4 o' Y4 a% L- t
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typedef struct6 z r5 C" l! `; }# u
{
# r1 [3 M0 e, m) u4 D# p: D ]4 E unsigned int a;7 \ [% u$ N) N3 X! g1 `* [
unsigned int b;9 A; K% u$ u# h. y) K
unsigned int packet_cout;
1 ^5 K5 t9 y6 [0 W; s2 F}RX_MSG_PROTOCOL, *pRX_MSG_PROTOCOL;
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: a' H9 u+ W, J! ]void read_MSG_buffer(int *baseaddr);6 ^) }; m4 u/ f7 `
unsigned int count_copy = 0;/ I- z( q; ^8 y7 d6 O( x5 p* w
8 e7 s. T8 p# Z3 ^/ Sint main()1 z1 [3 _% B7 h4 ~0 ]
{
0 t& i. f# b: d4 Q int fd;1 K5 A; F" w2 Q& Q
int *mem = NULL;
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- d6 P1 @$ q" Z8 i6 h/ l2 U if((fd = open("/dev/mem", O_RDWR)) <0)" m1 K0 ^, |! T1 Q3 A
{
1 j9 |( K4 ?' X3 D* o perror("open error");0 ]" f0 ]; m% h' J0 Z0 z& U
return -1;1 q; I0 [" g. C0 r8 D
}
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mem = mmap((void *)SHAER_RAM_BASE_ADDR, SHAER_RAM_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);, S8 V; _3 H0 ^4 p, T
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while(1)
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read_MSG_buffer(mem);
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. p+ }# U1 `9 Xvoid read_MSG_buffer(int *baseaddr)
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pRX_MSG_PROTOCOL pshreRAM = NULL;
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3 X4 z0 k' f# W3 w2 d+ `# ^$ } pshreRAM = (pRX_MSG_PROTOCOL)baseaddr;) E1 y2 l4 K# P5 b& b% b
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if(pshreRAM->packet_cout != count_copy)
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! f( B+ |/ P" E% P2 }9 { printf("a is %d\n", pshreRAM->a);3 @* i0 X. B5 ?- ~9 M$ c5 W
printf("b is %d\n", pshreRAM->b);
R. J5 |, f0 Y. R+ ^. B# }/ L printf("count is %d\n", pshreRAM->packet_cout);
6 C7 c- z2 M. e: u count_copy = pshreRAM->packet_cout;( v6 q) y& Q! O/ ?5 ]( ]
}
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{
$ x3 `2 E& D4 W6 y: u4 E printf("No effective message!\n");7 B4 u D Y/ d5 }* K
}
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# x# }/ s* i7 h8 I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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