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本帖最后由 zc_fly 于 2014-8-19 16:53 编辑
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- b3 T( v: R9 h* ^# L; lOMAPL138的ARM端对共享区内存进行直接访问,代码如下所示:#include <stdio.h># r* H8 B B' B! ~" Y
#include <unistd.h>
' }, K" h/ [6 o#include <sys/mman.h>
3 _& O3 y0 H( r9 S9 Z9 J/ Q#include <sys/types.h>
) j' Q. N& q; N( r( P% b) q+ ~/ l#include <fcntl.h>
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#define SHAER_RAM_BASE_ADDR (0x80000000) " _. \* c1 a7 q2 `5 F1 I6 C9 L C9 n
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typedef struct `, [- N l8 o! [1 ^
{
; n/ Q9 x. v& k% y: l5 \ e- ?% e! } unsigned int a;
3 w% h' B4 p4 o6 A' v8 D* K K unsigned int b;7 j2 b# M: T+ P" a+ {' {& F/ a
unsigned int packet_cout; J# W3 Q8 G( @6 n* q# G
}RX_MSG_PROTOCOL, *pRX_MSG_PROTOCOL;
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void read_MSG_buffer(pRX_MSG_PROTOCOL pshreRAM);/ M% q5 a# j) P$ ?' |
unsigned int count_copy = 0;+ z, l* p: N$ {; H6 H7 W+ H% Y+ ]
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n1 O, X. e K3 i; a. j) }% S$ B* v( zint main()+ l& U2 W- r9 H( d& ] [, I; Z
{
# I' d- q, N2 u5 U pRX_MSG_PROTOCOL pshreRAM = NULL;3 L" q1 J) A! o
pshreRAM = (pRX_MSG_PROTOCOL)SHAER_RAM_BASE_ADDR;
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& e0 [' u. h& u3 G$ B4 ~9 l. {: r while(1)* ?. X- i# p6 i4 ?1 W
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read_MSG_buffer(pshreRAM);
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_: J4 l: Z! G% m2 {& _; k# L# Wvoid read_MSG_buffer(pRX_MSG_PROTOCOL pshreRAM)
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7 ]0 U& |$ m9 [ RX_MSG_PROTOCOL buf;
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buf.a = pshreRAM->a;
) B: H9 {& Y0 t6 [: P7 y i( r buf.b = pshreRAM->b;
; [5 I( u, S7 \ buf.packet_cout = pshreRAM->packet_cout;
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7 C& ?4 O! {# u* r& ] if(buf.packet_cout != count_copy)$ }8 ]$ i, w# L1 \) b+ e
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printf("a is %d\n", buf.a); ?* S( ]# U# b' q
printf("b is %d\n", buf.b);
# S* z8 L0 c/ M printf("count is %d\n", buf.packet_cout);
* ]0 ^2 p4 ?2 E- _$ [ count_copy = buf.packet_cout;" y" }4 \% C, |) a8 y/ J
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else
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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。8 @* S! Z6 h" `4 m# _+ a+ c
使用下面代码,对内存使用了mmap函数后:/ `, l8 b4 M6 p, r0 C; E
#include <stdio.h>/ V$ H1 _% r0 ~. [% R. r; X0 O. H
#include <unistd.h>- o! S* B7 `4 d% {+ V2 N
#include <sys/mman.h>' N9 U! d/ L7 m/ j- w
#include <sys/types.h>
# W4 D' I* ^0 j) v* j3 i0 [#include <fcntl.h>
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1 }( R$ n2 g% C: n0 a3 P#define SHAER_RAM_BASE_ADDR (0x80000000)
; v, l4 n8 s8 ]#define SHAER_RAM_SIZE (0x20000) + Y7 G8 P0 z7 ?) Y
' R2 a6 @0 A( qtypedef struct
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6 Q! j' M' Y! h: ^ unsigned int a;0 G8 Z9 M2 n, h7 b3 N; \1 [
unsigned int b;
) E! f* I0 `9 ?" U% o5 C5 {; M. S$ u4 d% \' B unsigned int packet_cout;6 z9 d) J7 z: c( U
}RX_MSG_PROTOCOL, *pRX_MSG_PROTOCOL;
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void read_MSG_buffer(int *baseaddr);- R1 y0 j% ?$ S$ B) E1 y+ ?
unsigned int count_copy = 0;
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int main()
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% s* {0 r& B$ H Z- K$ a int fd;
& v* ^& o8 j F2 M) B# H% P, v int *mem = NULL;, U6 Y# O4 Y2 p
4 e7 @! b- e/ ~% Q" J) n& j if((fd = open("/dev/mem", O_RDWR)) <0)4 {, @3 D( V1 @0 b
{# i5 ?9 N( }+ `/ D) j% P/ s
perror("open error");
2 P' M# Q! H6 T2 T return -1;) V% O( b# h! A; F8 e, ^: `. L D
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( o! J% A Z/ G0 f% ^ mem = mmap((void *)SHAER_RAM_BASE_ADDR, SHAER_RAM_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);+ B/ q" f7 U/ s* O
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while(1) Y; U+ u# s8 ~* v; D/ X. F- t @+ G6 a
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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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pshreRAM = (pRX_MSG_PROTOCOL)baseaddr;: T O ^4 f) o% q
+ `# \3 h: Z4 O" q( ?% q if(pshreRAM->packet_cout != count_copy)' }+ g6 g6 g& M4 a9 k) v1 |3 f0 _' ~
{
$ {$ v0 v% ]1 ^ a: L printf("a is %d\n", pshreRAM->a);
& c5 O4 z! }: \ printf("b is %d\n", pshreRAM->b);
& F4 N" P4 X* B- X printf("count is %d\n", pshreRAM->packet_cout);; ?, ?! B* M& J: `% T
count_copy = pshreRAM->packet_cout;
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{
! c& V8 S! d# l( j3 `, I B printf("No effective message!\n");' @5 q Z( t. d& M4 s
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}
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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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