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本帖最后由 zc_fly 于 2014-8-19 16:53 编辑 , e8 n9 F+ |/ B
( [- b7 ~+ {4 r$ K. u8 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>
& c6 v# Y1 M: B: Z#include <unistd.h>
3 t3 \ Y5 A$ T/ s#include <sys/mman.h>
* {6 f! n/ Y" d e' B. N#include <sys/types.h>; R% m% W" Z0 T3 s0 x! ]
#include <fcntl.h>" {4 _5 V! |9 Z5 K3 a. c
n' Y5 A/ ?' u0 m6 Q* ?, a* i, O* l#define SHAER_RAM_BASE_ADDR (0x80000000) # c) z4 ~2 E' s$ _
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typedef struct
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2 J# A. y( Z7 i0 ] unsigned int a;4 y) U4 y$ u: f& C* G, Z8 c5 {
unsigned int b;8 p7 ~* U% v7 r' z9 ~* G9 K! g3 n+ R
unsigned int packet_cout;6 i$ J* C! H7 f8 e0 Y+ S
}RX_MSG_PROTOCOL, *pRX_MSG_PROTOCOL;8 q$ u7 h5 s& o: J0 K
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void read_MSG_buffer(pRX_MSG_PROTOCOL pshreRAM);8 p: G% G. m C% S( h) x! W/ f
unsigned int count_copy = 0; ]; @# z& t. _8 R9 b6 l
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int main()
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pRX_MSG_PROTOCOL pshreRAM = NULL;0 Z% g1 Z# F, ~. ~
pshreRAM = (pRX_MSG_PROTOCOL)SHAER_RAM_BASE_ADDR;
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7 h) q; P8 U7 g' _% p* d& C4 V while(1)6 I, h7 j7 E6 N
{
9 e6 M+ @1 H. Z( D* j read_MSG_buffer(pshreRAM);" Y$ j% d: r1 U- ^$ f
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}
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void read_MSG_buffer(pRX_MSG_PROTOCOL pshreRAM)
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- |- B. e& F1 E$ ?. k, t, A& X RX_MSG_PROTOCOL buf;+ l' u4 q U/ v0 V+ H) ?; Q
6 G% k! T9 g3 t3 E buf.a = pshreRAM->a;
: g/ e) T: \; ~% \: V buf.b = pshreRAM->b;
! O7 y0 f* Z8 |# Q2 \( J buf.packet_cout = pshreRAM->packet_cout;
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if(buf.packet_cout != count_copy)0 ^; v* R5 d) B- m2 b4 K) Q9 Q9 H7 O
{
" w2 i3 f5 w6 T1 }1 D) P! k, M printf("a is %d\n", buf.a);
1 i: r) d$ H ~ i5 }+ S printf("b is %d\n", buf.b);
2 ^3 T8 w1 j' ^( c F: ] printf("count is %d\n", buf.packet_cout);
. C0 c2 {! A" P9 \ count_copy = buf.packet_cout;
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else: f) L+ w) Q$ b- [2 A6 G* `- ]6 h
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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; ]2 K& I" N使用下面代码,对内存使用了mmap函数后:
, T% ^6 z& l+ |) K+ n% k#include <stdio.h>! `$ p; w+ ~& Q3 v' q
#include <unistd.h>
; ~, j& V5 }, c% o3 U x#include <sys/mman.h>
( D0 A$ D, D. |* K2 g8 ?! |#include <sys/types.h>
" b) O( ? w/ b/ _#include <fcntl.h>
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. _" F+ g1 n( h* j8 Z#define SHAER_RAM_BASE_ADDR (0x80000000). t) Y$ h% B0 y4 k9 |1 i. w. _9 u
#define SHAER_RAM_SIZE (0x20000) / i/ U1 L# o0 `$ A* Z8 p) S8 }
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typedef struct
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. a9 E) K: V* z unsigned int a;0 T i% g) u0 \1 g* S4 i6 G
unsigned int b;
8 C( V9 G* N, S+ f2 H unsigned int packet_cout;
, X; G& R6 D! {- C! Q5 p# G}RX_MSG_PROTOCOL, *pRX_MSG_PROTOCOL;
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1 a! t. D$ Q8 x" p/ ovoid read_MSG_buffer(int *baseaddr);
. e9 L- Y* @+ y4 I9 ~, W+ U0 i' Lunsigned int count_copy = 0;8 i+ R# ]' ?1 r( M+ O
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int main()) ?* F" S0 _1 B9 j$ Z" ]
{
: D8 P" l: G+ x# w2 A int fd;; S+ m7 }" y# i- [0 s$ n9 o* w
int *mem = NULL;5 T- d% h" X: p9 \ D
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if((fd = open("/dev/mem", O_RDWR)) <0)
; ~( R, _$ d/ S$ E {
8 F" A, l9 ]- k, F1 l perror("open error");
! ~* [: u5 y- Z" c& T A& p return -1;, ]1 E8 B; ?* e, c# U' c
}7 K0 q# E( S: j9 B% J
) p0 w) \9 a- ?; Z mem = mmap((void *)SHAER_RAM_BASE_ADDR, SHAER_RAM_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
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while(1)
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f& {3 |4 B0 P. R3 P8 y6 K read_MSG_buffer(mem);
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void read_MSG_buffer(int *baseaddr)
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pRX_MSG_PROTOCOL pshreRAM = NULL;
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9 h: z/ N+ O, m pshreRAM = (pRX_MSG_PROTOCOL)baseaddr;
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if(pshreRAM->packet_cout != count_copy), r, x" k1 V8 K/ [# S2 ?% L
{
- p, p! h6 I' `7 W l l" b printf("a is %d\n", pshreRAM->a);/ o" a7 \+ \( `2 S8 r9 x8 P0 k& S3 B
printf("b is %d\n", pshreRAM->b);
! X" e: |* B& L, e& D7 q# P d8 S printf("count is %d\n", pshreRAM->packet_cout);8 H1 M/ E2 B3 s' ]1 S2 Q$ d
count_copy = pshreRAM->packet_cout;6 ^- f* F+ q4 l( w
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else, \5 f6 ^/ p$ Q5 d3 O5 F
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printf("No effective message!\n");- N( `- z, Y, O5 K. `* l
}) z1 ?6 { Y# U' Q# y: L
}
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- s/ I7 T& F( G% e+ s2 ^4 @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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