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本帖最后由 zc_fly 于 2014-8-19 16:53 编辑
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+ g- h) D* ]1 x0 M1 s4 ]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>& \& s0 |; N$ L0 `
#include <unistd.h>6 {" c/ d1 |3 u) Z
#include <sys/mman.h>
( _' [* e; r! p9 k9 g. ^) M* z#include <sys/types.h>! R7 s7 c% w9 [
#include <fcntl.h>% g% v, W0 p3 U1 W& V
4 H9 ?; ? c6 f; x a#define SHAER_RAM_BASE_ADDR (0x80000000) 5 H* F2 X4 x/ D1 S, v5 ]: i0 f0 v
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typedef struct& U7 O1 _: B4 o+ D
{
~ n+ E, ]/ E: J \ unsigned int a;# L. P, a: s2 r1 E, t" C& Q' D
unsigned int b;& P( j* @: r; ]; v
unsigned int packet_cout;
, l* K& P7 b3 s; h0 p3 a; x& a9 W+ F}RX_MSG_PROTOCOL, *pRX_MSG_PROTOCOL;( V& e$ |7 h @$ }2 t0 y
) |3 Q: U" a4 q, Uvoid read_MSG_buffer(pRX_MSG_PROTOCOL pshreRAM);: m) t7 S) Y( F5 {" ^+ j% I8 A B" R
unsigned int count_copy = 0;
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int main()% N9 K+ \4 T' z; n Y1 Z( N: Z
{
5 N, j- G9 h9 N pRX_MSG_PROTOCOL pshreRAM = NULL;
- z- S: a9 \3 @& d+ Q5 H pshreRAM = (pRX_MSG_PROTOCOL)SHAER_RAM_BASE_ADDR;
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while(1)# R/ l+ a* Z( d1 y: n
{
' y% z+ o& n# ]7 t read_MSG_buffer(pshreRAM);- i% P$ f/ o% [" m
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}
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u% }4 ^ n4 tvoid read_MSG_buffer(pRX_MSG_PROTOCOL pshreRAM)
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. W$ j: a0 p9 D: |9 t; s4 s+ q RX_MSG_PROTOCOL buf;9 L) a9 ^3 q9 G* _2 ^( g
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buf.a = pshreRAM->a;
" J: y2 f3 s; Y- Y6 x! S+ w buf.b = pshreRAM->b;7 ^( p( a v* }* k% K
buf.packet_cout = pshreRAM->packet_cout;
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if(buf.packet_cout != count_copy)
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4 u( f7 c2 W0 ~" p printf("a is %d\n", buf.a);
( a V5 h. T. f: p3 z printf("b is %d\n", buf.b);" w4 {4 Y6 ]1 o3 N3 S% t
printf("count is %d\n", buf.packet_cout);* U9 l% w( ]8 _* Z- j2 m9 Y* U, u: M
count_copy = buf.packet_cout;
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' Y7 v1 S, Q& Q( \3 [8 H else
# F2 C2 g6 N3 _( A& e9 i {
5 o8 @- k" p; D6 H printf("No effective message!");" n) i4 S" A6 g* c7 [$ L, [
}
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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。; O) E: l' X% V/ o N8 J) p' R
使用下面代码,对内存使用了mmap函数后:
2 B( _) V5 Z6 M9 P0 v+ w/ S#include <stdio.h>' I# `* A# ^ m
#include <unistd.h>- p% a' p/ y3 p5 C1 l7 W
#include <sys/mman.h>
% u1 ~9 t& A8 c- N! n+ I" d- q#include <sys/types.h>7 O8 `- R6 ?1 G+ B/ C
#include <fcntl.h>6 G! w' ^: m& e- b9 s
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#define SHAER_RAM_BASE_ADDR (0x80000000)
3 a4 q: v$ l5 Q5 c4 @3 N#define SHAER_RAM_SIZE (0x20000) : t9 C0 l; ]$ F M f0 p3 }
) e6 v8 \) d/ w; a- r1 E! ltypedef struct
, v/ R/ b7 ~+ }+ }; ~. k2 F{
0 L2 c5 e3 ]% D5 m# V# q- |: p unsigned int a;
# n3 @* @/ R7 A3 M4 }+ E' @ unsigned int b;9 H% S! v( l3 ~$ C
unsigned int packet_cout;0 A& d9 H) ]' Y, d$ ^+ P1 l" I
}RX_MSG_PROTOCOL, *pRX_MSG_PROTOCOL;
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; Q3 e: h' A3 H8 h0 ]/ Ivoid read_MSG_buffer(int *baseaddr);4 ^" b- O# b/ b/ B3 V. W5 j, `
unsigned int count_copy = 0;
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0 b+ X) o9 {: Jint main()
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int fd;1 a0 M( ], H u; I; F; ~
int *mem = NULL;4 a( ^/ Z* S; O
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if((fd = open("/dev/mem", O_RDWR)) <0) y f( |* o3 d% E) v0 z7 b
{! l# {7 U) r# W; @4 h
perror("open error");
; d. \& v, {' _5 m7 z3 _ return -1;
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8 Y0 M* w6 W+ | k mem = mmap((void *)SHAER_RAM_BASE_ADDR, SHAER_RAM_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);) B, I, [9 U8 T- Z! ^2 J; q
1 C$ S( I m" y. b while(1), T( p4 U6 B4 V1 x* D1 a, Q
{
. }- ?" y, ]* t' j, `0 g read_MSG_buffer(mem);
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void read_MSG_buffer(int *baseaddr)$ h; `8 q/ l- F0 g- s, U# L8 Q# A
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pRX_MSG_PROTOCOL pshreRAM = NULL;/ L* m- y: o$ Q9 E1 }0 _2 v' ]3 E/ }
# S# O$ e0 s( u$ ~ pshreRAM = (pRX_MSG_PROTOCOL)baseaddr;
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if(pshreRAM->packet_cout != count_copy)
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4 T/ J4 a: M2 T* e+ C5 x printf("a is %d\n", pshreRAM->a);5 a& }1 L) G4 s$ G7 ~7 T
printf("b is %d\n", pshreRAM->b);
" v: \3 p+ M7 I6 f printf("count is %d\n", pshreRAM->packet_cout);3 p7 a& y& k5 B! i2 ~5 G$ A
count_copy = pshreRAM->packet_cout;
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: D8 c( a9 B( F9 ~* k5 B else
& Y. B8 T" z2 C/ x3 W, p {
9 C1 i) u2 ?. ~ printf("No effective message!\n");
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}
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% \5 Q1 B' @5 k! o |8 G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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