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本帖最后由 zc_fly 于 2014-8-19 16:53 编辑 # `! e8 K7 Q7 {- t0 T# A
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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>0 k( M2 B1 g4 ?4 m
#include <unistd.h>& p% Q3 m0 J2 W2 Y
#include <sys/mman.h>
9 f1 z, X" n) G4 ~1 I. |#include <sys/types.h>
" [9 L4 Y1 k$ n# `& D; ~/ [#include <fcntl.h>) I/ l1 H4 ~/ _8 n9 R
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#define SHAER_RAM_BASE_ADDR (0x80000000) * j, y' l" g# m1 u! F
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typedef struct/ G) f! F+ r" a
{
& j. V# d- n: W unsigned int a;; u1 W4 f0 n5 F' b
unsigned int b;2 A# i. M. O; s$ `/ [/ W- e
unsigned int packet_cout;4 {6 P" j( | Y* S' j
}RX_MSG_PROTOCOL, *pRX_MSG_PROTOCOL;) k# @8 b6 T- e
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void read_MSG_buffer(pRX_MSG_PROTOCOL pshreRAM);
5 S. w7 `: e' V' Munsigned int count_copy = 0;
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int main()- o' }5 {* ?5 D S+ k1 d+ G
{
" O3 Z- Z3 n) l/ l pRX_MSG_PROTOCOL pshreRAM = NULL;
4 G9 Q. Q( b, J4 i( \ pshreRAM = (pRX_MSG_PROTOCOL)SHAER_RAM_BASE_ADDR;9 y& w; |) v. s& t# v+ k
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while(1)
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8 j' h' x# e- s. I" o. b0 i6 ] read_MSG_buffer(pshreRAM);
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; |$ r( ]1 @7 ~. E4 ^2 uvoid read_MSG_buffer(pRX_MSG_PROTOCOL pshreRAM)/ n5 O1 U2 c. }% ]$ k4 t
{
) ]' l8 y' }& M$ }9 ?! X RX_MSG_PROTOCOL buf;
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: H' @8 P7 Z% u! `) s buf.a = pshreRAM->a;; V% g: _3 I J" t: g+ L
buf.b = pshreRAM->b;9 v$ r3 x) b# o5 o9 B5 A
buf.packet_cout = pshreRAM->packet_cout;
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if(buf.packet_cout != count_copy)0 u7 |3 L" y0 Y: f( K
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printf("a is %d\n", buf.a);* B* c' b1 w5 P0 ]" q! u- I: n5 O5 A
printf("b is %d\n", buf.b);
A1 [$ ?" H. ]5 H& i printf("count is %d\n", buf.packet_cout);
7 v( Y8 L0 b) H$ S4 H: ^$ A count_copy = buf.packet_cout;
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- ^ w" L4 v% w/ b' q else
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printf("No effective message!");
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! _7 s; }0 W2 s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' s) T8 M4 x! t. o使用下面代码,对内存使用了mmap函数后:" ~, x! r! C {
#include <stdio.h>, X7 J! l, g; }- A. W3 h
#include <unistd.h>4 ?3 _8 {! d/ I1 i2 W H' w2 m
#include <sys/mman.h>
) w& ]* [; a4 k8 g ?) [#include <sys/types.h>% i5 Z( J4 c$ K" B7 j
#include <fcntl.h>
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#define SHAER_RAM_BASE_ADDR (0x80000000)
( [. b% O7 d! `+ e#define SHAER_RAM_SIZE (0x20000)
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typedef struct9 e X( T$ U! g6 ~+ F/ l7 Q
{
6 K; Y4 }+ h3 S- d unsigned int a;% h( |3 J5 O' ^; z& H* |! f! `9 j
unsigned int b;
& p {2 x, N% O5 N- s8 X; h unsigned int packet_cout;
0 |2 \+ Y* i" g' l}RX_MSG_PROTOCOL, *pRX_MSG_PROTOCOL;+ B4 @; w0 n6 G/ [; ?1 G2 x3 ~
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void read_MSG_buffer(int *baseaddr);
9 t9 ^# G/ p# V5 t0 B( Gunsigned int count_copy = 0;
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int main()
+ j# [2 k6 [- N# h+ P H/ U{
8 Y& m4 j" F! F$ Y& D: C& _ int fd;
) W! _3 P5 Z% b; @: Y5 C; H, L$ d8 O int *mem = NULL;( P% } v! f6 ~( W
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if((fd = open("/dev/mem", O_RDWR)) <0): L6 _; R, G$ h" C& r3 W$ O
{
' r! R1 E. P4 _ perror("open error");
0 G2 r3 X" d d return -1;5 g/ Z& X H( q5 R- _7 Y5 I
}
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1 X# {! |) x* b+ g: ?. O: c6 H- r mem = mmap((void *)SHAER_RAM_BASE_ADDR, SHAER_RAM_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);& \# O0 C5 T; i' I. `5 l
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while(1)
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read_MSG_buffer(mem);0 n- F) a8 R1 _) n
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}
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3 _, [5 x$ x6 K; `5 avoid read_MSG_buffer(int *baseaddr)
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pRX_MSG_PROTOCOL pshreRAM = NULL;% i1 J/ ]1 B6 |) [: H# J
1 A" p/ N3 F; T8 W pshreRAM = (pRX_MSG_PROTOCOL)baseaddr;
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+ t: d4 C; G: g# z9 d- V if(pshreRAM->packet_cout != count_copy)7 o* e' [# [. `) \8 p
{
, o& B" r: n& S printf("a is %d\n", pshreRAM->a);
) y' I; z, O/ u: v" M9 A/ k printf("b is %d\n", pshreRAM->b);3 ~( q+ ]& R' p! ?
printf("count is %d\n", pshreRAM->packet_cout);
2 e5 q, H1 {/ s; a: g count_copy = pshreRAM->packet_cout;: O( @! V* S+ D. H
}
5 n$ c, H3 c0 ^- `" g4 B7 q else
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/ K7 v0 \1 R t8 V printf("No effective message!\n"); u [) b; j; v3 W1 C
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}
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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???3 a# z( |) H1 U3 ^6 f3 q& {! y% Y
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