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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>
1 R9 m% L+ R/ K4 |5 `#include <unistd.h># P% m- s, [& [
#include <sys/mman.h>
6 J4 I3 e. B5 f: t8 A! {1 o#include <sys/types.h>
1 ~, C8 ^" i z: S% t) F0 A#include <fcntl.h>
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#define SHAER_RAM_BASE_ADDR (0x80000000) 1 d3 {! @7 `: i! F/ O
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typedef struct
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# ?4 T6 Y9 x* T) w unsigned int a;
3 D a1 I0 ` [: O8 k7 r6 A- G# Z unsigned int b;2 M! ~3 t6 V4 T1 w X! Z- B9 }7 `
unsigned int packet_cout;
! P5 `/ H2 }6 O1 M. F+ h}RX_MSG_PROTOCOL, *pRX_MSG_PROTOCOL;: _6 l0 o, Y# p
4 M4 s+ T+ ^5 G$ e E5 H zvoid read_MSG_buffer(pRX_MSG_PROTOCOL pshreRAM);
+ H" d% m- K! B- Q9 M% |unsigned int count_copy = 0;
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( x& v' M P1 B4 Sint main()" I4 E* U. f# H% O( B8 `4 r
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pRX_MSG_PROTOCOL pshreRAM = NULL;7 F) H8 l% z/ p2 S0 c) C% C0 B
pshreRAM = (pRX_MSG_PROTOCOL)SHAER_RAM_BASE_ADDR;: ]6 t2 @9 a3 N( J+ w
/ M1 B( Q$ G- X W/ i; f/ f! M while(1)
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( M! M- f! s) \# ? read_MSG_buffer(pshreRAM);
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void read_MSG_buffer(pRX_MSG_PROTOCOL pshreRAM)/ O4 H7 A3 u; c) y- k) e2 L
{
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. t+ C) o5 {1 Y! X3 F4 s buf.a = pshreRAM->a;
: }6 T+ ]! N% ~3 b% Y- `1 } buf.b = pshreRAM->b;1 m2 M0 P" R6 N
buf.packet_cout = pshreRAM->packet_cout;/ B+ v1 Y& M/ B+ r. j7 ]& H
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if(buf.packet_cout != count_copy)
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. |2 W$ |! m. \; G* w" O+ p printf("a is %d\n", buf.a);
# G1 v+ `8 ~/ B! b0 T printf("b is %d\n", buf.b);1 s) Z7 H A, d8 h* Y* y; h
printf("count is %d\n", buf.packet_cout);* z' t% i4 L( g# @* M
count_copy = buf.packet_cout;
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else8 V/ o! w( E! o! S, I: T) }$ C1 A" N7 U
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printf("No effective message!");
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8 ~% R! ~( t* y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。0 D6 {' K5 C0 s$ [7 ^+ Q5 j
使用下面代码,对内存使用了mmap函数后:
- ]4 y2 D$ n8 G1 Q& D! K& ]#include <stdio.h>
6 k6 ]& @# Q! _( A0 l#include <unistd.h>
6 F/ [+ u( \5 r, r/ N# G#include <sys/mman.h>
( g4 d) V7 V9 p#include <sys/types.h>3 a9 |8 A# m* K4 V
#include <fcntl.h>
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#define SHAER_RAM_BASE_ADDR (0x80000000)- O: N7 c# k4 ]7 L
#define SHAER_RAM_SIZE (0x20000)
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7 u9 c8 P4 \$ d& i$ k. x5 Wtypedef struct
0 W. N; \: g! U- S{
& x! j5 F, k. C; ]: E; l unsigned int a;7 J8 W3 L8 t6 v. r
unsigned int b;
3 O. M6 g6 Z6 ^; o( t6 f. X unsigned int packet_cout;8 b: ?2 _2 T, f8 C2 m
}RX_MSG_PROTOCOL, *pRX_MSG_PROTOCOL;3 _1 ~% K3 Q: d3 \$ D+ n0 t2 [
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void read_MSG_buffer(int *baseaddr);+ v. v, Z5 _) q# Y
unsigned int count_copy = 0;
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int main()+ j" O# @ A: G. X8 K
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int fd;
& m6 U2 ]7 D' m$ v/ C5 A8 L int *mem = NULL;7 ?" q8 M+ \. N4 F; N, \
5 [/ m* ^, C i' C- p if((fd = open("/dev/mem", O_RDWR)) <0)
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perror("open error");: R( w4 H. {! Y# N" V
return -1;* t, ]7 `5 M0 C7 [" Z ?
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( p0 ^* y# Z' c+ D% ~9 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) J. R: s9 P! U' b
{
+ l5 v0 H% B! o# i+ }- F read_MSG_buffer(mem);
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. ?8 S! v4 f6 J9 g, |void read_MSG_buffer(int *baseaddr)
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pRX_MSG_PROTOCOL pshreRAM = NULL;% }+ G0 |; D; M7 E! N4 C
+ g; h4 \3 Q* H pshreRAM = (pRX_MSG_PROTOCOL)baseaddr;' ], D Y0 G! g5 m
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if(pshreRAM->packet_cout != count_copy)
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printf("a is %d\n", pshreRAM->a);+ }0 Y. p6 a( W) l4 Y: ?& } w
printf("b is %d\n", pshreRAM->b);
# s5 S" [0 _1 c6 {- A printf("count is %d\n", pshreRAM->packet_cout);0 I. O0 S" [& w4 x
count_copy = pshreRAM->packet_cout;
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else
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printf("No effective message!\n");
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6 X1 T. t0 \2 f, g( A; Y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???, F, z/ K I6 ?) r% Q- \7 c0 y; u
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