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本帖最后由 zc_fly 于 2014-8-19 16:53 编辑 5 W$ ~6 ]8 J; m+ k4 n H$ V
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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>
: ?4 g W- F/ f" T& N4 j( R# D#include <unistd.h>
& H8 }& |) a& u9 k w#include <sys/mman.h>
5 ~1 y( A! }3 C% r1 ~#include <sys/types.h>
9 `2 Y1 _# G0 i& Y% N' Q5 L6 ^* G0 n#include <fcntl.h>
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#define SHAER_RAM_BASE_ADDR (0x80000000)
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- `% d- l9 F5 w5 H, _0 gtypedef struct
' d: I/ {% \5 q9 e5 h{
5 D' u, a5 u& c+ W* e unsigned int a;
Y, t% j$ b9 [4 x$ w unsigned int b;
3 `$ ~' u4 O* F+ ~ unsigned int packet_cout;1 O+ B, K( b$ F, s# ]1 l) [5 \/ _. v4 s
}RX_MSG_PROTOCOL, *pRX_MSG_PROTOCOL;+ l1 g0 o3 i6 x+ W# y4 x
/ X1 [& n, Y/ W* X' I8 N& tvoid read_MSG_buffer(pRX_MSG_PROTOCOL pshreRAM);
* w; e) |. s$ s( ]unsigned int count_copy = 0;4 s z& c! Y! w: T: P7 X$ c
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int main()5 M, q4 s; u6 ^7 ]# g9 d& P1 ]; j3 g
{
: e* a! q( z- M2 S( \ pRX_MSG_PROTOCOL pshreRAM = NULL;
- O1 l, W# z5 X& i' }% q/ {8 Q/ i- ?" r pshreRAM = (pRX_MSG_PROTOCOL)SHAER_RAM_BASE_ADDR;! X. y- w j9 ^
) M6 n+ W% y0 @8 M. Y while(1)" M! O" `: X$ V8 Y( _4 a1 l3 C
{
# T8 C+ I# Z1 N+ g5 J+ Q read_MSG_buffer(pshreRAM);
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void read_MSG_buffer(pRX_MSG_PROTOCOL pshreRAM)2 R5 _( {+ G8 X: k
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RX_MSG_PROTOCOL buf;
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, R6 e* c6 T& u, g buf.a = pshreRAM->a;- x I8 o: E6 a* E/ w
buf.b = pshreRAM->b;
# M c0 _; v6 G& P5 |# H) Q buf.packet_cout = pshreRAM->packet_cout; v4 S0 O' S" b) m+ W% C
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if(buf.packet_cout != count_copy)
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printf("a is %d\n", buf.a);
" G! v \, m4 [( g4 D [ printf("b is %d\n", buf.b);0 M0 i3 Z$ q' W! ~
printf("count is %d\n", buf.packet_cout);& j9 \; U, _3 q: m% n
count_copy = buf.packet_cout;
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else* z# e# ?8 j2 y7 B( p' x
{
9 }* p! j- d% Z+ a printf("No effective message!");! [; t- k7 G6 m- s6 u1 n1 z; v* W
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}
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5 }! }7 l% c, U- B1 ]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。# }& {7 j: V* @2 E
使用下面代码,对内存使用了mmap函数后:: C4 `6 B4 Q1 [' }6 b* H
#include <stdio.h>
6 Q* t/ ^9 `1 T5 G7 H3 B#include <unistd.h>' O3 s: Q; E0 b" c: \" X' f
#include <sys/mman.h>3 g9 ~3 h0 t/ h# Q, l
#include <sys/types.h>6 ?' R+ F- F5 A8 S6 X2 W
#include <fcntl.h>( k5 c# U# w% b" ^0 H8 b
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#define SHAER_RAM_BASE_ADDR (0x80000000)+ c* U P6 ?- h$ C) K
#define SHAER_RAM_SIZE (0x20000)
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typedef struct; G- V, H; q; J# G" W1 Z0 Q9 Q
{- b- m1 N& q* S. w
unsigned int a;
; T' F- H" u/ h1 Z; m! I; A unsigned int b;
6 X% g3 d# _5 q+ h; b$ J unsigned int packet_cout;
. L& P0 C d$ f' ?' u" t! x}RX_MSG_PROTOCOL, *pRX_MSG_PROTOCOL;
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2 v5 ], ~; V. K. ovoid read_MSG_buffer(int *baseaddr);9 D/ o; w- S( D! E3 `5 U
unsigned int count_copy = 0;) e: X3 @: r' w' c" c
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int main()- X3 f1 n, s# O% c0 |
{
. Q- o; y. V( ?1 S# }0 J5 Y int fd;
4 S" m' B |/ {$ u, ^: I int *mem = NULL;% g# k( x% X! {
8 z0 V* r( x8 a0 f% E# e0 H3 S if((fd = open("/dev/mem", O_RDWR)) <0)
; H/ R& M/ k& {9 V/ X {
9 C9 @2 Z" i/ o' _$ G perror("open error");
) ~) r2 Y2 Y3 `, {) g2 U1 C0 v; B* a return -1;, S. h1 Q8 M+ y8 U8 G
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% _7 Q, f* b. `& c mem = mmap((void *)SHAER_RAM_BASE_ADDR, SHAER_RAM_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);; Q) V( V: P o1 Q3 t
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while(1)9 X4 \2 ]- b# C/ C% u
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read_MSG_buffer(mem);
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9 Z" l/ G5 @9 D7 d4 hvoid read_MSG_buffer(int *baseaddr)3 `" a) p3 D+ G2 R! }
{
& S5 C8 m+ w3 ?; w& Y/ H pRX_MSG_PROTOCOL pshreRAM = NULL;3 j: m3 H/ t; y2 d7 r- A& H
1 w7 ?3 V" x" v" w pshreRAM = (pRX_MSG_PROTOCOL)baseaddr;
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if(pshreRAM->packet_cout != count_copy)
+ s. N) Z' Y) v) u {
' w: g/ m& T- f; x4 T, w- @ printf("a is %d\n", pshreRAM->a);( W0 `. X% ?2 a; W: ?
printf("b is %d\n", pshreRAM->b);
0 @+ q4 N/ A. N# c, [- R+ u printf("count is %d\n", pshreRAM->packet_cout);
, d, E3 c7 p* {3 R4 M3 q9 V; S" J$ F count_copy = pshreRAM->packet_cout;" X# R. L6 g. D% y, e0 y, n
}
; A g1 z3 x5 T5 G/ m) m' S else
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printf("No effective message!\n");$ T3 i2 K4 q9 E2 ?5 T- Y. |
}
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- ?4 C1 J8 p6 Y) R3 n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???! E" }/ w! s8 u
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