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本帖最后由 zc_fly 于 2014-8-19 16:53 编辑
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: o2 _. k# [* X% x1 COMAPL138的ARM端对共享区内存进行直接访问,代码如下所示:#include <stdio.h>' W1 d( o( i8 Q+ U
#include <unistd.h>
/ W5 |- f: B& |- j# }: a0 @#include <sys/mman.h>; G% ?* I [" j1 r+ L; O
#include <sys/types.h>
! i6 d. Z4 ^+ ^& L#include <fcntl.h>
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; m8 M1 N) K( b* D$ X7 h6 m#define SHAER_RAM_BASE_ADDR (0x80000000)
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5 m9 }( l/ o) ^3 E$ ztypedef struct
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8 X8 |# J8 C- P2 _. K; Z' N unsigned int a;
- Z) _7 s Y2 ^0 _; @& G unsigned int b;+ }3 S+ j# `" ^. e s+ l
unsigned int packet_cout;( T) {6 S* {6 a6 H
}RX_MSG_PROTOCOL, *pRX_MSG_PROTOCOL;3 c' v& R- N& m" }+ A
- C5 f& M7 t; L ~void read_MSG_buffer(pRX_MSG_PROTOCOL pshreRAM);
; |/ Y* v( c% K% K6 g/ a/ V5 dunsigned int count_copy = 0;
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! A/ U8 }' E) S4 x' X' P" r" vint main()
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pRX_MSG_PROTOCOL pshreRAM = NULL;9 N6 x! k9 j" z/ r( A
pshreRAM = (pRX_MSG_PROTOCOL)SHAER_RAM_BASE_ADDR;
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while(1)7 Z. k0 j/ C6 s5 B; q. ^
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read_MSG_buffer(pshreRAM);# ?& D. E6 p' m6 p) K1 J; |
}
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. Q; e Z& i: i8 g2 M* e$ ~void read_MSG_buffer(pRX_MSG_PROTOCOL pshreRAM)& s( r" Z6 a K7 K, N
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RX_MSG_PROTOCOL buf;2 j b+ x3 y. [/ }+ {- J
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buf.a = pshreRAM->a;
* ?( l1 f$ b) |. e/ { buf.b = pshreRAM->b;
f& f" Y i1 U I& ~% u buf.packet_cout = pshreRAM->packet_cout;
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if(buf.packet_cout != count_copy)% C' l) {0 m+ y
{
0 G: j: l5 i- z6 ]/ Y; g printf("a is %d\n", buf.a);( t3 v2 f: N O3 ?. \! o
printf("b is %d\n", buf.b);
, v; ~) m6 t& R9 \2 L* R printf("count is %d\n", buf.packet_cout);
9 j/ ?( ~9 K. C r2 I: _; o count_copy = buf.packet_cout;
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printf("No effective message!");
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, v: a1 z1 ]0 ?6 c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。
+ h0 X: r7 |" o- I* `! q使用下面代码,对内存使用了mmap函数后:
/ G1 f; L6 a" ~5 }: L' K% W" \#include <stdio.h>
5 ]( x$ ^3 l ]/ ~$ N! Q6 U7 y#include <unistd.h>
; U# `. |' n& @ C) _* e. B#include <sys/mman.h>
& K/ L7 P7 l! B+ h2 {#include <sys/types.h>! }; M" I+ x" [4 ^ \) B# [
#include <fcntl.h>4 `" T; T* h) Q+ }
: U$ o# l( H4 G* k6 t#define SHAER_RAM_BASE_ADDR (0x80000000)4 a8 A# G& [0 J9 z
#define SHAER_RAM_SIZE (0x20000)
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" o N7 f$ }% F6 y0 k Rtypedef struct8 ~, p0 G/ ?$ {3 S/ L& X& d
{
7 z8 ?0 T( {0 p! V, h% z4 v) B unsigned int a;
# e6 x6 P) g- ?: j unsigned int b;/ |# x% G+ a# i: |, }4 _/ Q; _: p
unsigned int packet_cout;
, e$ N g S" R: z4 K" R& x( O7 S, N2 C}RX_MSG_PROTOCOL, *pRX_MSG_PROTOCOL;4 [$ E2 b) F( N' O& v8 I
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void read_MSG_buffer(int *baseaddr);
; ~( @, a: W: v0 runsigned int count_copy = 0;
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int main()1 b1 T: C# E& w+ f% J0 V7 z
{6 z5 a7 F3 |0 N; a' `' W
int fd;% M0 ]" U* D2 D% R
int *mem = NULL;
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5 y0 d6 S$ @& h; ^! m' h8 T8 a if((fd = open("/dev/mem", O_RDWR)) <0)' p. g# c, X7 }4 f& [; u
{
# `* G. j$ g8 R5 ?& U perror("open error");
* K7 ]% a. h4 x return -1;1 K4 j5 x) f/ _* v. J% v
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0 L% U" }, q4 ]( [, e% F mem = mmap((void *)SHAER_RAM_BASE_ADDR, SHAER_RAM_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);1 G: R: u2 n" T- A$ }7 }
; Z9 n& p; Q! E( Q; { while(1)
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read_MSG_buffer(mem);4 _6 u3 O7 f+ x
} 1 `% }, i" `" [4 F# T4 R0 y
}; n Y5 s/ k& u# n4 i" W: T( C
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void read_MSG_buffer(int *baseaddr)( F% N8 `9 o2 g. N& S* v
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pRX_MSG_PROTOCOL pshreRAM = NULL;
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0 b( S$ K% U, c/ }! G5 t) }) G pshreRAM = (pRX_MSG_PROTOCOL)baseaddr;$ v4 m. a: D/ S h3 E
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if(pshreRAM->packet_cout != count_copy)
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9 ]9 Q$ O/ T( A& s) r, V* Y* z printf("a is %d\n", pshreRAM->a);
+ `7 `) k2 H) w7 q printf("b is %d\n", pshreRAM->b);
; W6 r% K! p" c, P printf("count is %d\n", pshreRAM->packet_cout);0 D% N7 \4 U% V! t7 n5 c5 D
count_copy = pshreRAM->packet_cout;! [( g! ?. s+ d' B% M! F
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else
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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???
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