IPC problem

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compilax

Joined: 18 Feb 2004
Posts: 56

compilax 05 Oct 2004, 05:08

Hi. I'm working on a little X type server (and later window manager) for MenuetOS. It waits for a message, and depending on the first byte of the message, it either draws an image to the working buffer, copies the working buffer to the screen, or sends back an error code. The simple program I'm using to test it sends two messages in sequence, but it appears that only one message can be in the queue at a time, meaning that the second message doesnt get through.
Can there be more than one message in the queue? Is there some way of indicating wether a message got through?

Thanks in advance, Compilax.

05 Oct 2004, 05:08

spideros1

Joined: 17 Jan 2004
Posts: 77
Location: Poland

spideros1 05 Oct 2004, 18:11

Here is C code from my libipc:

Code:

typedef struct {    volatile unsigned long lock;    unsigned long free_ptr;    char __mem[0];} ipc_hdr_t;typedef struct {    unsigned long sender_pid;    unsigned long msg_length;    char message[0];} ipc_msg_t;ipc_msg_t * ipc_receive_msg(ipc_hdr_t * hdr){ ipc_msg_t * msg, * tmp; int k,copysize; lock_msg_queue(hdr); if(!ipc_messages_avail(hdr)) {  unlock_msg_queue(hdr);  return NULL; } tmp=(ipc_msg_t *)hdr->__mem; msg=(ipc_msg_t *)malloc(tmp->msg_length+sizeof(ipc_msg_t)); if(!msg) {  unlock_msg_queue(hdr);  return NULL; } k=tmp->msg_length+8; memcpy(msg,tmp,k); hdr->free_ptr-=k; copysize=hdr->free_ptr-8; if(copysize) {  memcpy(hdr->__mem,hdr->__mem+k,copysize); } unlock_msg_queue(hdr); return msg;}

05 Oct 2004, 18:11

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