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本帖最后由 zc_fly 于 2014-8-19 16:53 编辑
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3 p1 z8 g8 S- V9 J5 ROMAPL138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 k: U& L( ], N! A" h! `, u#include <unistd.h>! P3 s4 y1 ~8 E5 W( y7 J3 a
#include <sys/mman.h>! Q% s( F% V. m3 k4 ^4 q
#include <sys/types.h>3 w3 O/ [1 W; t6 @3 R, J7 G; J, W
#include <fcntl.h>
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: Q) @1 _1 v* q( U+ ?#define SHAER_RAM_BASE_ADDR (0x80000000) 1 M; l) X9 k$ T( Z s$ }
. H# ] ^5 I) ^ @typedef struct* d, y, T4 ^/ O8 v W
{ R1 W' O2 i6 \0 p) H7 b1 F* K
unsigned int a;
) ?( A# _& T* p2 x0 R, ?6 C unsigned int b;
) _ ?- E! t5 m7 |1 j( R unsigned int packet_cout;7 D. x3 j: x+ e
}RX_MSG_PROTOCOL, *pRX_MSG_PROTOCOL;) m) \% X( R! K* T4 q& y
2 s; d4 k' x& w' L; Gvoid read_MSG_buffer(pRX_MSG_PROTOCOL pshreRAM);
1 m- J$ d8 k) Y- v) Eunsigned int count_copy = 0;
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$ D! |8 p0 I1 S7 S0 K% t' u, Bint main()
2 A' }/ j# w3 j$ Y. y) {{
1 e$ m5 ?9 l# z; a' b) B; u5 `8 g! a pRX_MSG_PROTOCOL pshreRAM = NULL;
8 V9 K5 X% @2 {: B pshreRAM = (pRX_MSG_PROTOCOL)SHAER_RAM_BASE_ADDR;
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while(1)
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$ F* w' E: f5 ~9 A n# m read_MSG_buffer(pshreRAM);- N5 @( D4 g2 z% q
}
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) F) L; O# F' i2 G4 b/ ^void read_MSG_buffer(pRX_MSG_PROTOCOL pshreRAM)
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4 j/ V' ~; S u- r/ ^6 z! Z RX_MSG_PROTOCOL buf;
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buf.a = pshreRAM->a;
( ^* o+ e/ |/ y9 V+ Y' ] buf.b = pshreRAM->b;, {% _- N* @- ^) G2 b7 A; p
buf.packet_cout = pshreRAM->packet_cout;
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if(buf.packet_cout != count_copy)
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printf("a is %d\n", buf.a);
" C6 d, q2 d) i( G printf("b is %d\n", buf.b);
: ^% E; D) T F" J7 O. q printf("count is %d\n", buf.packet_cout);( b: r# r8 ^ D3 i$ M+ V
count_copy = buf.packet_cout;: l7 x8 P! e7 f: `% q( L
}
6 J4 d' j( h3 r; g else
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printf("No effective message!");
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: y/ w8 m( k$ {" n' [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。
3 Z& K( Q, Y% X0 x: w使用下面代码,对内存使用了mmap函数后:
7 B: z, l7 _# E- R( R; d2 L9 u#include <stdio.h>' k! a; `( {9 o3 N: y$ s+ b
#include <unistd.h>% \# h# G7 B4 q( n( M8 X
#include <sys/mman.h>: N/ u, X: E, C8 ^
#include <sys/types.h>
, M! X! ~- u9 N& J#include <fcntl.h>
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. [$ l0 w# K- p#define SHAER_RAM_BASE_ADDR (0x80000000)' h2 t3 K. I/ O* M
#define SHAER_RAM_SIZE (0x20000) ! C/ \2 E$ H# ^' l# c* z) U
! g/ x( z: ?, p% W6 Ztypedef struct
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unsigned int a;
9 l6 E0 A4 E$ f \& y" u unsigned int b;5 X7 g, l& [7 I! s$ C
unsigned int packet_cout;4 W. ^& \ \& d$ q' q3 t
}RX_MSG_PROTOCOL, *pRX_MSG_PROTOCOL;
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void read_MSG_buffer(int *baseaddr);9 M7 {' R+ [ r9 J
unsigned int count_copy = 0;9 [2 ~: c% K" t% [9 G
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int main()
/ F# T; ?0 C" R# U7 @* r+ ] L{
7 W, s+ t0 c; F; F. l) u' W int fd;
" w9 A5 h4 X9 @3 n4 \: o; h& B/ v int *mem = NULL;
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if((fd = open("/dev/mem", O_RDWR)) <0). }! U% r' G; Z0 ]* ~9 a
{
, a. ]: B2 j. m- `' p9 y+ n n. P8 H perror("open error");
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- J$ r+ G8 L4 W2 V4 h) @ mem = mmap((void *)SHAER_RAM_BASE_ADDR, SHAER_RAM_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
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while(1)/ C w( f6 e& k2 x
{
5 e3 t, i1 i1 N, j4 A" p read_MSG_buffer(mem); K( X! }+ n% v+ G
}
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void read_MSG_buffer(int *baseaddr)6 {8 a5 a8 J7 X% ]+ l4 \ F
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pRX_MSG_PROTOCOL pshreRAM = NULL;# M2 o. |$ e: G& h. ~/ {
3 D( I" c& `9 @ P" V pshreRAM = (pRX_MSG_PROTOCOL)baseaddr;+ h: @, J: g- C7 c7 q. `4 o
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if(pshreRAM->packet_cout != count_copy); ?/ v" U6 y; e6 h
{
( Y2 T, u! J, k& ~ printf("a is %d\n", pshreRAM->a);. o2 m5 V d n, u+ s9 }
printf("b is %d\n", pshreRAM->b);* x3 O/ @/ o+ x3 R! Q/ Q6 X
printf("count is %d\n", pshreRAM->packet_cout);; z9 K' A/ n" e) m. J: ?
count_copy = pshreRAM->packet_cout;3 X9 {& ]% ?/ y2 n Y' h
}
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printf("No effective message!\n"); k9 q8 _. T$ t
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}
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* a1 \$ ?3 C% h. \: _; j0 b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???' Y1 |- H7 I- o# Y! S
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