web.c

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#include "web.h"

struct web_shm* create_web_shm(void) {

    int shm_id = shmget(SHMEM_DATA_KEY, sizeof(struct web_shm), IPC_CREAT | SHMEM_PERMISSIONS);
    if (shm_id == -1) {
        rl_log(ERROR, "In create_web_shm: failed to get shared data memory id; %d message: %s", errno, strerror(errno));
        return NULL;
    }
    struct web_shm* web_data = (struct web_shm*) shmat(shm_id, NULL, 0);

    if (web_data == (void *) -1) {
        rl_log(ERROR, "In create_web_shm: failed to map shared data memory; %d message: %s", errno, strerror(errno));
        return NULL;
    }
    
    return web_data;
}

struct web_shm* open_web_shm(void) {

    int shm_id = shmget(SHMEM_DATA_KEY, sizeof(struct web_shm), SHMEM_PERMISSIONS);
    if (shm_id == -1) {
        rl_log(ERROR, "In create_web_shm: failed to get shared data memory id; %d message: %s", errno, strerror(errno));
        return NULL;
    }
    struct web_shm* web_data = (struct web_shm*) shmat(shm_id, NULL, 0);

    if (web_data == (void *) -1) {
        rl_log(ERROR, "In create_web_shm: failed to map shared data memory; %d message: %s", errno, strerror(errno));
        return NULL;
    }
    
    return web_data;
}

void reset_buffer(struct ringbuffer* buffer, int element_size, int length) {
    buffer->element_size = element_size;
    buffer->length = length;
    buffer->filled = 0;
    buffer->head = 0;
}

void buffer_add(struct ringbuffer* buffer, int64_t* data) {
    memcpy((buffer->data) + buffer->head*buffer->element_size/sizeof(int64_t), data, buffer->element_size);
    if(buffer->filled < buffer->length) {
        buffer->filled++;
    }
    buffer->head = (buffer->head + 1) % buffer->length;
    
}

int64_t* buffer_get(struct ringbuffer* buffer, int num) {
    int pos = ((int)buffer->head + (int)buffer->length - 1 - num) % (int)buffer->length;
    
    return buffer->data + pos*buffer->element_size/sizeof(int64_t);
}