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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>. S2 O5 Q3 \. d5 I
#include <unistd.h>' R: B) B; t/ ~/ N" |# P% V2 D
#include <sys/mman.h>
9 Z5 r# [! U1 s4 l: p- k#include <sys/types.h>3 Q) i) m! N7 O7 f0 D" o3 v
#include <fcntl.h>
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#define SHAER_RAM_BASE_ADDR (0x80000000)
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: Y: N. x$ j4 E! A6 ?typedef struct
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& _* J+ \, _7 [. Z6 H0 f1 ? unsigned int a;
" r" b; F8 @% ~7 g' d1 Z4 Z unsigned int b;# D6 r* U9 g! [$ z6 a' g% G
unsigned int packet_cout;+ w# m% ?$ @2 L5 X$ S
}RX_MSG_PROTOCOL, *pRX_MSG_PROTOCOL;/ n l0 B; r0 E
) K; Z2 l* r' G9 h/ E0 fvoid read_MSG_buffer(pRX_MSG_PROTOCOL pshreRAM);
) j# F7 e3 ?( funsigned int count_copy = 0;
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int main()% T2 R- }* l" ^& C+ G3 M7 f
{
& y# ^- ?! G, P, T pRX_MSG_PROTOCOL pshreRAM = NULL;5 `2 J- o9 G+ p7 S5 n3 ^. G
pshreRAM = (pRX_MSG_PROTOCOL)SHAER_RAM_BASE_ADDR;( ~$ ]; |2 t; g& B0 g4 l: W8 g
, F6 h# A$ p( X* M& [: W# [ while(1)9 J% c& F( I- X" Q. [4 ?9 a# Y0 B
{
7 j4 k Y( [# L8 F4 o7 e read_MSG_buffer(pshreRAM);+ k+ u1 E5 {5 F
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void read_MSG_buffer(pRX_MSG_PROTOCOL pshreRAM)1 O/ C5 X3 b$ n4 a5 b( a. E, c
{
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( c- Z) m; v' r2 a* H! w* E buf.a = pshreRAM->a;
: \8 S6 ?$ l( O7 G buf.b = pshreRAM->b;
) n1 R7 z; g$ F buf.packet_cout = pshreRAM->packet_cout;% ~9 a5 E2 s$ w2 S# @$ J+ \( ^
% @* k% |+ `( Z) x if(buf.packet_cout != count_copy)
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* Q' ^" N0 |9 }. e M O; I+ e printf("a is %d\n", buf.a);8 Z$ w$ i3 c% [) {
printf("b is %d\n", buf.b);1 w$ n6 i6 h- l. B
printf("count is %d\n", buf.packet_cout);
7 V& ?( C7 |% S6 E" I count_copy = buf.packet_cout;
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else
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# N' p9 W3 a, E* n# T) w6 g- q) d& N printf("No effective message!");
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但是出现segmentation fault的问题,这是什么原因啊???我在DSP端烧写了一段小程序,向共享区0x80000000位置写入数据,用CCS 测试发现写入成功。
$ Y, S4 v( k5 b: ~* \! v' @使用下面代码,对内存使用了mmap函数后:2 K( Z7 A9 F, s, E1 c
#include <stdio.h>
7 ~( b! z# W/ `, _#include <unistd.h>* u" N& s) H& U5 ^2 g8 j8 G
#include <sys/mman.h>
4 d0 B% _3 M$ z6 j0 n& t#include <sys/types.h>
6 O1 H1 q+ k" ~! }5 ]3 S- w$ o#include <fcntl.h>
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7 o; u) l3 ^; ?9 S, J#define SHAER_RAM_BASE_ADDR (0x80000000)
" e- W% l6 H2 t4 w: T( u' \#define SHAER_RAM_SIZE (0x20000)
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8 F# N' H5 b# I3 V, r; q9 Xtypedef struct/ B$ u) x8 x$ X: Y; D' M5 E# i+ C6 N
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unsigned int a;- y4 o. A! ~) T* ?* |$ m
unsigned int b;5 X- G7 i0 s3 b$ M% z
unsigned int packet_cout;7 _( D% N8 Z8 ~8 b) E
}RX_MSG_PROTOCOL, *pRX_MSG_PROTOCOL;5 y1 J- v' v1 l5 @+ S& T& n
7 [, e$ r, \& d7 C6 gvoid read_MSG_buffer(int *baseaddr);
- |* y$ u, t+ y# o- S' N4 nunsigned int count_copy = 0;; R: E* M5 U1 \) K
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int main()
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int fd;8 v$ T- Y/ Q2 R J; p9 _- H3 v# F
int *mem = NULL;5 B& ~0 Z! j- Z4 H( U
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if((fd = open("/dev/mem", O_RDWR)) <0)
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perror("open error");
: u3 s) X2 P( I# r' I* N/ t: W6 K3 O return -1;
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: A" J! X( ~) e6 o! _1 R mem = mmap((void *)SHAER_RAM_BASE_ADDR, SHAER_RAM_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);8 J+ Q q! X# T# {1 k( g* g
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while(1)
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8 Y2 r5 Q% u% X. H2 k8 o2 H) t! b1 R read_MSG_buffer(mem);. u6 y) X+ e) P( R) S
}
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9 u& G3 L4 d, j$ a( X' t$ z. bvoid read_MSG_buffer(int *baseaddr)- B8 X- Q, g) _, D8 y
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pRX_MSG_PROTOCOL pshreRAM = NULL;
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pshreRAM = (pRX_MSG_PROTOCOL)baseaddr;
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; ~# a4 e7 v! a& G7 n! Y( H( w0 E& [( Y if(pshreRAM->packet_cout != count_copy)
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printf("a is %d\n", pshreRAM->a);2 o" D; b2 J8 Q$ u4 E. E/ F. \ \
printf("b is %d\n", pshreRAM->b);
) Y" h) i* N9 ]( Q$ C printf("count is %d\n", pshreRAM->packet_cout);) W* d" {/ `8 ]( m7 V5 d% Z+ e
count_copy = pshreRAM->packet_cout;9 I$ A9 W) f# U, V% a8 F5 [
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else
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# J4 j8 \- }* H0 L printf("No effective message!\n");
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i9 L; d `% V5 T9 ^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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