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本帖最后由 zc_fly 于 2014-8-19 16:53 编辑
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- R, t4 o8 F, j4 q- KOMAPL138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 y3 d! u: Q. ]' A+ s, { m#include <unistd.h>
: p7 a ]; x& w7 x7 A- G% X#include <sys/mman.h>
; y# e4 w, u' Y5 f- p#include <sys/types.h>
" w6 Y8 C+ i- v#include <fcntl.h>
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- o% A M, Y4 q: n9 |. g#define SHAER_RAM_BASE_ADDR (0x80000000) - v) T+ Y6 C6 E3 c; Y+ v7 w, k
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typedef struct2 t( n' d6 q4 t) O
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unsigned int a;8 V6 |9 _0 W: B6 I ^% r
unsigned int b;. b7 y5 y6 k9 l1 G
unsigned int packet_cout;( z# P- X. e% H8 X6 m3 q/ S0 K1 B
}RX_MSG_PROTOCOL, *pRX_MSG_PROTOCOL;6 w* E: E! M% a
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void read_MSG_buffer(pRX_MSG_PROTOCOL pshreRAM);
# U$ a+ F/ H. a5 C" x: ~$ J; M$ Aunsigned int count_copy = 0;
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) l% z4 N9 P$ h/ b1 E0 p! Hint main()7 Y4 y0 n* k3 h3 J q% r
{
& S- O' ]5 e' h# ?% q" H pRX_MSG_PROTOCOL pshreRAM = NULL;, N( n) m- h" a$ @9 b. V4 Z! [
pshreRAM = (pRX_MSG_PROTOCOL)SHAER_RAM_BASE_ADDR;+ t% x0 A+ ~$ Z% o4 p; i
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while(1)
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read_MSG_buffer(pshreRAM);5 }5 Y# Z `- v+ G
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void read_MSG_buffer(pRX_MSG_PROTOCOL pshreRAM)
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RX_MSG_PROTOCOL buf;$ h: ?$ f+ _9 V0 u0 y7 p" O
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buf.a = pshreRAM->a;! M) Z& T! h% L t5 N0 y
buf.b = pshreRAM->b;% n4 t3 @' Y H, G
buf.packet_cout = pshreRAM->packet_cout;) L: P/ {) z" ~
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if(buf.packet_cout != count_copy)$ Y- k+ J/ B4 J; O9 u: G' j
{
% D' _3 C7 i. C0 Y& r. `! b5 f printf("a is %d\n", buf.a);0 j f @3 c! v
printf("b is %d\n", buf.b);7 Y/ D) g& e& h2 Z" W
printf("count is %d\n", buf.packet_cout);
, O& ?5 H% s* O: V- S count_copy = buf.packet_cout;
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printf("No effective message!");# c- ?6 r. n+ Y1 l0 n
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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。
9 j# b6 V7 M, V' t) b8 v# U6 k$ N/ E使用下面代码,对内存使用了mmap函数后: G8 f+ k/ r: v* s. f. m2 B
#include <stdio.h>0 n1 h1 W5 I, O5 v0 }) v/ a* R
#include <unistd.h> g; _. n; H& h
#include <sys/mman.h>
0 E# H) I: _0 ]9 k$ j$ c+ U |$ z) d1 y#include <sys/types.h>7 O; R# Z) Q# _+ ]6 E- ?+ k9 S( \
#include <fcntl.h>
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+ d, S. T& J& S7 d2 Q#define SHAER_RAM_BASE_ADDR (0x80000000)
" f; c: m+ n" m7 @#define SHAER_RAM_SIZE (0x20000) / w. i/ a% {1 `% I' w' D6 J5 }1 Z
$ @# Z% j/ e* u/ [0 Xtypedef struct
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unsigned int a;1 H' ?+ p' p( C- W0 a0 ]
unsigned int b;" j' b' T7 M+ I/ N
unsigned int packet_cout;5 b. w) f" R4 P% U7 v* _. i
}RX_MSG_PROTOCOL, *pRX_MSG_PROTOCOL;0 h* u2 J3 E7 \* c f
2 R3 k. E9 R: v1 Gvoid read_MSG_buffer(int *baseaddr);
. g2 Y; [& _+ Y# F+ Qunsigned int count_copy = 0;
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int main()
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int fd;
+ m9 h& Z' A3 L6 y3 X' } int *mem = NULL;% d K* V5 i1 s
) X9 j# _4 w5 _: k! A- O$ G if((fd = open("/dev/mem", O_RDWR)) <0)
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: Y- P Q, C0 ]" f6 z perror("open error");2 C- h C* C9 i2 l4 I
return -1;& i6 z2 `" {' o, B
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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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while(1)
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v, m; \7 v6 P. F; C9 @$ V+ _ read_MSG_buffer(mem);
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$ w; c# x/ E/ rvoid read_MSG_buffer(int *baseaddr)+ D" `' Y: h: n( e1 B, g5 W. Q
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pRX_MSG_PROTOCOL pshreRAM = NULL;
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! e- i* a6 Q# Y2 k( z4 N pshreRAM = (pRX_MSG_PROTOCOL)baseaddr;
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) \1 y0 Q, Q6 s# I4 l if(pshreRAM->packet_cout != count_copy)
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printf("a is %d\n", pshreRAM->a);# `- L7 u! h6 k4 A' n" I6 ~
printf("b is %d\n", pshreRAM->b);0 Z4 z+ ]9 l; @, C9 _' Z9 V( ~
printf("count is %d\n", pshreRAM->packet_cout);' |4 P( F4 G- l5 D" e. {
count_copy = pshreRAM->packet_cout;9 K1 o, M/ S9 ~3 Z: \0 n: X' s# J
}; V$ N( _) R. U B+ U( b
else( ?0 s! U1 ^6 B# O+ S
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printf("No effective message!\n");
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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???1 r7 P" k, d3 z& v
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