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本帖最后由 zc_fly 于 2014-8-19 16:53 编辑
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+ h6 C; D9 [+ EOMAPL138的ARM端对共享区内存进行直接访问,代码如下所示:#include <stdio.h>
8 A9 d" N; t1 e. V9 J; P& P#include <unistd.h>/ w3 O$ p" P: X( o, e
#include <sys/mman.h>
. k1 n5 Q- p" ^/ L) f#include <sys/types.h>
, P+ y# |1 |! S4 c; v; r4 z#include <fcntl.h>' v4 b+ |( x% g s+ M3 _- |
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#define SHAER_RAM_BASE_ADDR (0x80000000) $ c3 J. O! W* ?. n# u* n
* S, Q, S& e6 i1 A8 o S4 @typedef struct
# _. i- v; p; K' c" J% `, J; i{( {$ j# ~9 F, H: r" _+ ?/ a
unsigned int a;6 Z6 I/ O7 {8 h$ ?
unsigned int b;
1 r' \0 F: Y% F8 g Z unsigned int packet_cout; U M" f' P' o, q' X$ l9 P
}RX_MSG_PROTOCOL, *pRX_MSG_PROTOCOL;. b; t |6 l4 Z7 g
! O& h$ ?, M5 Q* t# mvoid read_MSG_buffer(pRX_MSG_PROTOCOL pshreRAM);
: c+ N6 ]" t' O: c0 } Kunsigned int count_copy = 0;; [4 e0 `. F! {* }5 M5 Y
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int main()0 e% }1 o, }4 _8 ^: E8 D/ Q" p- c
{
+ C6 j# J) d1 Q0 d x pRX_MSG_PROTOCOL pshreRAM = NULL;
0 d) \/ v7 W. q9 Y pshreRAM = (pRX_MSG_PROTOCOL)SHAER_RAM_BASE_ADDR;3 z) | q& a& y/ `9 R3 B
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while(1). U R( f: G$ X3 ~. t* T- _8 m
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read_MSG_buffer(pshreRAM);
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void read_MSG_buffer(pRX_MSG_PROTOCOL pshreRAM)
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5 {: w( A# F0 h8 Y, E8 `+ r. c RX_MSG_PROTOCOL buf;
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5 Y+ R8 }6 _% r7 }4 f2 f buf.a = pshreRAM->a;
% d) E9 `9 T8 j8 F buf.b = pshreRAM->b;
2 P# }! ?. P8 _+ g7 E% m; F7 } buf.packet_cout = pshreRAM->packet_cout;+ A$ N( N7 X. j$ D- c) c
" }0 b) M" {: K8 @* z( h2 j if(buf.packet_cout != count_copy)
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printf("a is %d\n", buf.a);' R& n' B& ?: k, M+ ], w/ h+ \
printf("b is %d\n", buf.b);
; j( K0 E4 T) o3 x2 { printf("count is %d\n", buf.packet_cout);# A- w4 ~+ X" P0 k
count_copy = buf.packet_cout; K" ^7 i( k [$ o* r) S8 {
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else
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& k$ U: g" F c, B2 { printf("No effective message!");
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2 R7 k3 T8 E$ N$ z* J6 U% H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。
- {6 k K4 o7 R2 L使用下面代码,对内存使用了mmap函数后:
8 N' C. e" Q- G% }#include <stdio.h>
8 l7 a ]& t9 j p- j, {9 }#include <unistd.h>
/ s% [0 i4 q! t- C#include <sys/mman.h>0 c6 k6 K/ ^9 J! c/ V
#include <sys/types.h>5 w8 ~3 @8 a3 l/ }5 C6 @) }; ]# W1 k
#include <fcntl.h>
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#define SHAER_RAM_BASE_ADDR (0x80000000)
9 g6 k( K/ \- j2 k- b! n. B6 {8 ?#define SHAER_RAM_SIZE (0x20000)
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* E- T2 U; o/ r0 b! N' B+ ~7 |5 A' \typedef struct
" F$ |$ L( S7 b5 O5 c+ o{
+ q3 b: M$ x6 D% v+ A1 r unsigned int a;
: b7 t8 O# {. F" X/ P- {( f. O; D unsigned int b;
$ Q2 t8 W }9 U, Y6 ]( _0 p unsigned int packet_cout;; F9 G: t7 o+ g$ a% B/ m
}RX_MSG_PROTOCOL, *pRX_MSG_PROTOCOL;) x. J, t# R5 |' Z2 Q9 M4 C# [
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void read_MSG_buffer(int *baseaddr);
# f/ y) I- N$ j, Tunsigned int count_copy = 0;
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" @* X4 F2 m8 C' ^1 hint main()' F9 c) R7 w5 `! l9 ]& h
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int fd;9 E0 G! p$ B1 `4 z$ |
int *mem = NULL;' Q8 I# e1 O' R& T. Y% v
& k9 c5 {, B* U3 q* Z if((fd = open("/dev/mem", O_RDWR)) <0)$ i, ?. a2 b) T* n
{) K. X: A6 o6 d6 G/ h t
perror("open error");
8 \ {$ ]1 y+ [( H; x3 F H return -1;- S2 l! k$ N0 z0 H# L# r
}
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6 K. r# \9 ^# H$ m mem = mmap((void *)SHAER_RAM_BASE_ADDR, SHAER_RAM_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);! L3 ]7 P8 I2 a
6 ?% m$ m! w5 F( p1 A2 k4 ` while(1)
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read_MSG_buffer(mem);
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}( {/ u3 s' B9 V! Z
- s5 j! c! l. Hvoid read_MSG_buffer(int *baseaddr)! `: U' b) z! n' b& D# _
{
7 ` b( N; w) r pRX_MSG_PROTOCOL pshreRAM = NULL; U" j& U1 y# Q: I% g+ b! |, R
( x- t5 o' P L; b pshreRAM = (pRX_MSG_PROTOCOL)baseaddr;* G5 q: K5 d4 M7 z+ z
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if(pshreRAM->packet_cout != count_copy)$ D% T; K7 X* V/ r1 |
{
9 H; I' C) ]& `+ ~1 ? printf("a is %d\n", pshreRAM->a);
. |8 j! X8 M( n printf("b is %d\n", pshreRAM->b);
8 E7 h, [) S. x1 ^/ I printf("count is %d\n", pshreRAM->packet_cout);& e) p1 g% j9 w6 M) Q3 E" x9 p
count_copy = pshreRAM->packet_cout;2 D0 ]/ O9 K5 d
}
% x0 Q0 T' A: V! Q, }9 ?/ p else
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# \" p. w1 _) d L; I1 Q5 P5 p8 P6 K printf("No effective message!\n");
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}
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8 l! G: P& ]' h5 L# X1 L, W* C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???- x' p( u6 ?4 i! X
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