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本帖最后由 zc_fly 于 2014-8-19 16:53 编辑 5 L1 {% G. i# K0 U
3 h- C" p- J8 R5 p4 `. WOMAPL138的ARM端对共享区内存进行直接访问,代码如下所示:#include <stdio.h>6 S9 F) h7 v, Y$ o
#include <unistd.h>) c4 c- {% \4 D3 w+ }, M% a
#include <sys/mman.h>
# K' Q# `# i+ ^8 j7 W5 @1 g- g#include <sys/types.h>4 \9 W( V% N( ^
#include <fcntl.h>
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#define SHAER_RAM_BASE_ADDR (0x80000000)
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+ R$ B# K" m* c+ X: c. Htypedef struct
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unsigned int a;
O: ]% q) o! E4 d2 z, ] unsigned int b;
2 F6 P X( t! n' V$ ` unsigned int packet_cout;$ m! _% `; p, A' ^
}RX_MSG_PROTOCOL, *pRX_MSG_PROTOCOL;9 |. k, [' S! F' z
, c' Y% E5 C; m- `7 l& u: |void read_MSG_buffer(pRX_MSG_PROTOCOL pshreRAM);9 E* V# N7 T6 H/ K& S, L* m/ W7 F; M
unsigned int count_copy = 0;
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int main()( ]- {6 N% t) F2 g; i
{
M7 Q' P! v- e$ m& M2 x+ | pRX_MSG_PROTOCOL pshreRAM = NULL;
6 y; m+ c) e) r0 c. S* y pshreRAM = (pRX_MSG_PROTOCOL)SHAER_RAM_BASE_ADDR;& C+ }! s. J1 ~3 h4 i4 h
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while(1)
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) X4 I' C2 `1 i6 g) h/ B: c' x% e read_MSG_buffer(pshreRAM);
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/ ~) B- d Q3 J. _1 n2 h7 bvoid read_MSG_buffer(pRX_MSG_PROTOCOL pshreRAM); \, w9 W' K5 L) T; R, H
{
; l- {3 k+ F" `" D8 ^ RX_MSG_PROTOCOL buf;
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2 k* k+ b& ?* s0 A buf.a = pshreRAM->a;
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buf.packet_cout = pshreRAM->packet_cout;) _& m6 } i# G( a+ U
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if(buf.packet_cout != count_copy)0 g7 n) m9 z) w! G
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printf("a is %d\n", buf.a);
# z8 e, {& L* ~) ]+ ~, d, n4 c printf("b is %d\n", buf.b); J# O1 i' g. d8 B8 \
printf("count is %d\n", buf.packet_cout);" \# j6 n3 Q( x \- | {
count_copy = buf.packet_cout;+ e+ e% Q( h' \: C4 I
}
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printf("No effective message!");+ Y/ k5 z* e: m$ d$ D9 \
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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。0 r! w1 Z! i' {8 ?2 I4 }
使用下面代码,对内存使用了mmap函数后:$ ~! [2 e. R: I
#include <stdio.h>! S' F/ m) t* ~8 a4 p2 x2 x
#include <unistd.h>
7 D! L, D$ z$ t) q2 t# D#include <sys/mman.h>$ @3 I2 w% m& }. s" Z. o4 }$ x: P
#include <sys/types.h>& p& P/ O- J/ A5 u9 ]! r: N
#include <fcntl.h>
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#define SHAER_RAM_BASE_ADDR (0x80000000)! `* R8 p" M. ?
#define SHAER_RAM_SIZE (0x20000) P( [7 _8 \; F2 |
" d' w! U* q# S; Rtypedef struct
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& {7 r& w- t% g" `# B unsigned int a;
: A) R- w X! ^# D/ E0 R unsigned int b;, l6 X4 Y# `. l1 ~( p p
unsigned int packet_cout;: {% y6 o$ U) Y% i. v( m$ s
}RX_MSG_PROTOCOL, *pRX_MSG_PROTOCOL;/ K) J+ |! I- t3 V, U
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void read_MSG_buffer(int *baseaddr);- Y* k* d* E- K- G$ J% a
unsigned int count_copy = 0;
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3 b: Q' H! F" w) N) b' i/ b3 \int main() X' N' U* `" A, f! T
{
3 |5 x/ G; }6 W0 m3 P int fd;- b1 }5 u X3 V7 R% H- V4 o3 o
int *mem = NULL;
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if((fd = open("/dev/mem", O_RDWR)) <0)
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perror("open error");
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mem = mmap((void *)SHAER_RAM_BASE_ADDR, SHAER_RAM_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
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4 D2 ~2 G% }9 T6 K1 D while(1)! b2 R4 z x1 L& R$ }7 S6 ]# `
{
# M3 S, ~1 p" X1 b0 z read_MSG_buffer(mem);
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, W% \) U/ _, `/ H s a, lvoid read_MSG_buffer(int *baseaddr)
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pRX_MSG_PROTOCOL pshreRAM = NULL;
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pshreRAM = (pRX_MSG_PROTOCOL)baseaddr;7 s) l2 ?% G/ o- N, d" M
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if(pshreRAM->packet_cout != count_copy)7 [ v; a W! Y I* h
{
! M% A* x1 a+ Z printf("a is %d\n", pshreRAM->a);- Q9 O$ v' q; U# @, I) {+ }& U
printf("b is %d\n", pshreRAM->b);8 Y, b) |$ ^3 _
printf("count is %d\n", pshreRAM->packet_cout);
! H7 H. z. E' e1 ?3 ` count_copy = pshreRAM->packet_cout;3 B; ?4 \7 A% L& F2 R' T
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printf("No effective message!\n");
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9 a6 _; c+ B' i& U% \& J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???6 [+ R+ D' T: H; n7 @
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