ashmem example list.cpp

#define SHM_NAME "test_mem"
#include <stdio.h>
#include <errno.h>
#include <sys/mman.h>
#include "ashmem.h"

int main(int argc, char **argv) {
    int shID = ashmem_create_region(SHM_NAME, 2);
    if (shID < 0)
    {
	perror("ashmem_create_region failed\n");
	return 1;
    }
    printf("ashmem_create_region: %d\n", shID);
    char *sh_buffer = (char*)mmap(NULL, 2, PROT_READ | PROT_WRITE, MAP_SHARED, shID, 0);
    if (sh_buffer == (char*)-1)
    {
	perror("mmap failed");
	return 1;
    }
    printf("PID=%d\n", getpid());
    int ch = getchar();
    sh_buffer[0] = ch;
    printf("Written 0x%x\n", ch);
    munmap(sh_buffer, 2);
    close(shID);
    return 0;
}

//read mem 
#define SHM_NAME "test_mem"
#include <stdio.h>
#include <errno.h>
#include <sys/mman.h>
#include "ashmem.h"

int main(int argc, char **argv) {
    int shID = ashmem_create_region(SHM_NAME, 2);
    if (shID < 0)
    {
	perror("ashmem_create_region failed\n");
	return 1;
    }
    // right here /dev/ashmem/test_mem is deleted
    printf("ashmem_create_region: %d\n", shID);
    char *sh_buffer = (char*)mmap(NULL, 2, PROT_READ | PROT_WRITE, MAP_SHARED, shID, 0);
    if (sh_buffer == (char*)-1)
    {
	perror("mmap failed");
	return 1;
    }
    printf("PID=%d", getpid());
    do
    {
	printf("VALUE = 0x%x\n", sh_buffer[0]);
    }
    while (getchar());
    return 0;
}

//

struct memArea{
    int *map;
    int fd;
    int size;
};
 
struct memArea maps[10];
int num = 0;
 
static jint getFD(JNIEnv *env, jclass cl, jstring path,jint size)
{
    const char *name = env->GetStringUTFChars(path,NULL);
    jint fd = open("/dev/ashmem",O_RDWR);
 
    ioctl(fd,ASHMEM_SET_NAME,name);
    ioctl(fd,ASHMEM_SET_SIZE,size);
 
    maps[num].size = size;
    maps[num].fd = fd;
    maps[num++].map = (int *)mmap(0,size,PROT_READ|PROT_WRITE,MAP_SHARED,fd,0);
 
    env->ReleaseStringUTFChars(path,name);
    return fd;
}
 
static jint setNum(JNIEnv *env, jclass cl,jint fd, jint pos,jint num)
{
    for(int i = 0; i < num; i++)
    {
        if(maps[i].fd == fd)
        {
            if(pos < (maps[i].size/ sizeof(int)))
            {
                maps[i].map[pos] = num;
                return 0;
            }
            return -1;
        }
    }
    return -1;
}
static jint getNum(JNIEnv *env, jclass cl,jint fd, jint pos)
{
    for(int i = 0; i < num; i++)
    {
        if(maps[i].fd == fd)
        {
            if(pos < (maps[i].size/ sizeof(int)))
            {
                return maps[i].map[pos];
            }
            return -1;
        }
    }
    return -1;
}