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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>0 u# U: [! I3 \6 X
#include <unistd.h>9 ~+ R! d/ _- B5 b& ?* N2 f r
#include <sys/mman.h>2 }6 B5 h! f2 _4 {( i# w
#include <sys/types.h>
. P; g8 P! ~; T% O* C3 S6 }#include <fcntl.h>
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" f- Y/ P3 R4 S9 ?7 f/ h( K#define SHAER_RAM_BASE_ADDR (0x80000000) . }' R. c* Y' M
( m% t0 s- A* Wtypedef struct$ w1 d1 L' t4 L+ g2 I, F
{
8 R) t. T0 N0 ~( |! _ unsigned int a;
1 s; J. A6 D% |6 X! m# }% D unsigned int b;( i0 p P0 b& x& N1 F5 y+ @: u
unsigned int packet_cout;
' W; [' C/ M6 ?3 D) H5 V/ {$ [* D$ T}RX_MSG_PROTOCOL, *pRX_MSG_PROTOCOL;
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7 }9 k9 l. P# x/ J7 e2 dvoid read_MSG_buffer(pRX_MSG_PROTOCOL pshreRAM);; I" |* t$ M9 ~7 w; V; i9 |: R
unsigned int count_copy = 0;
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5 k; T8 Y0 h3 [2 S4 ~int main()# [# F% u) ]# k, _. H7 p
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pRX_MSG_PROTOCOL pshreRAM = NULL;0 \7 n) q/ ~- x1 a1 U3 o: Z& _4 s
pshreRAM = (pRX_MSG_PROTOCOL)SHAER_RAM_BASE_ADDR;
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# i. k% c1 l! N while(1)
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read_MSG_buffer(pshreRAM);& @+ ` x$ M& a7 @; C6 E
}
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void read_MSG_buffer(pRX_MSG_PROTOCOL pshreRAM)# F7 b) [7 v( ~4 ~, V( ?
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RX_MSG_PROTOCOL buf;
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# o. z" W D. r- G2 ^2 r+ b* R" w9 \ buf.a = pshreRAM->a;
9 L" j3 g+ w0 ^* q/ n buf.b = pshreRAM->b;
) r/ f0 R4 ?) _* J6 i buf.packet_cout = pshreRAM->packet_cout;. h! P% u. X& M; O, z* {$ l
: I$ |) [+ [ g U! H if(buf.packet_cout != count_copy)* }5 @( p6 p4 M
{
% D4 @2 F6 {' P9 p9 J printf("a is %d\n", buf.a);+ y( l9 [' S( l4 @' e
printf("b is %d\n", buf.b);
& G1 s+ L* `( `7 [- R printf("count is %d\n", buf.packet_cout);5 M- x/ x! {! l' R! x! G
count_copy = buf.packet_cout;
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{
! _' p9 v& J) P' n printf("No effective message!");" @( [7 Y- v1 S. f, v5 y/ o. Q( G
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7 l. q7 Y' E2 ^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。
J0 e. T1 ~( ]& q L使用下面代码,对内存使用了mmap函数后:
; N3 O' ^8 X% s3 C#include <stdio.h>$ W% L( F% j- Q* H8 S
#include <unistd.h>
9 t# x4 c9 M8 m8 n' S0 Y0 y( Z' X#include <sys/mman.h>
) I3 ^; e N2 z#include <sys/types.h>8 p/ X" a& `7 T6 s8 h6 D% r, W8 u# K
#include <fcntl.h>
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# b( |; a c! ?6 l x5 A0 c#define SHAER_RAM_BASE_ADDR (0x80000000)
2 f8 m- B& U0 P7 ?" F1 ?& e' L; s#define SHAER_RAM_SIZE (0x20000) ) V: I2 c! h# h# Z9 Q: v
# ~4 i7 u# Z2 |) `! J6 ?' D0 Etypedef struct
& h( R5 I( }1 [{
9 j% d4 Y% M Y+ [9 G" L) D. r unsigned int a;
U# Y1 ? G) i0 r _. ?# V unsigned int b;4 z7 P* A$ C; b2 E
unsigned int packet_cout;
& e- T6 p+ L( q5 W$ x# M}RX_MSG_PROTOCOL, *pRX_MSG_PROTOCOL;+ D/ { r: a, D- i1 X
. T2 D$ ^ x6 rvoid read_MSG_buffer(int *baseaddr);4 R i( C* f; u; K5 d! M
unsigned int count_copy = 0;; \6 @7 ], J0 m
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int main()) j) J: ~( Y+ B- ^9 N9 T
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int fd;9 {1 e! `9 I0 C; B
int *mem = NULL;
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if((fd = open("/dev/mem", O_RDWR)) <0), K; {2 S0 d2 j' e
{
0 r6 x, I: h9 d. ]9 f2 v perror("open error");+ t2 b. q# n9 R- |& D
return -1;8 Q% f- `6 B9 \, ^( s
}
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mem = mmap((void *)SHAER_RAM_BASE_ADDR, SHAER_RAM_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);" o. l& [+ J8 Z" V$ D7 ~1 \
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while(1)
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& V1 m, ?1 j# ~: |9 Q9 G- A9 q read_MSG_buffer(mem);6 N' s0 I% A% K1 [ N6 X6 C
}
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void read_MSG_buffer(int *baseaddr)
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% y: ?3 G) w _& k pRX_MSG_PROTOCOL pshreRAM = NULL;
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pshreRAM = (pRX_MSG_PROTOCOL)baseaddr;* P6 L1 O d% n P# N& d/ W
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if(pshreRAM->packet_cout != count_copy)
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6 ]6 b6 P( `) n. W0 f% b; f% f printf("a is %d\n", pshreRAM->a);2 @) d2 G& C: o0 C; ]6 b/ B
printf("b is %d\n", pshreRAM->b);
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count_copy = pshreRAM->packet_cout;
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1 [: F O3 F! X! U- }8 U printf("No effective message!\n");0 `# }) D* V$ p1 q( y
}
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& ?3 `: m% Y: _% k, R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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