3915b660fd
Polling for the data-transfer window to become open is wasteful. We can eliminate the polling loop by using hw_step() as the handler for an xfer_window_changed() event. If the window is already open at the time of instantiation, then xfer_window_changed() may never be called. We can cover this case by using hw_step() as the step() method of a one-shot process. Since the signature for an xfer_window_changed() method is identical to the signature for a process step() method, the same function can be used for both. Signed-off-by: Michael Brown <mcb30@ipxe.org>
70 lines
1.6 KiB
C
70 lines
1.6 KiB
C
#include <stddef.h>
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#include <stdlib.h>
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#include <string.h>
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#include <errno.h>
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#include <ipxe/refcnt.h>
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#include <ipxe/process.h>
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#include <ipxe/xfer.h>
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#include <ipxe/open.h>
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/** @file
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*
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* "Hello World" data source
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*
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*/
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struct hw {
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struct refcnt refcnt;
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struct interface xfer;
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struct process process;
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};
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static const char hw_msg[] = "Hello world!\n";
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static void hw_finished ( struct hw *hw, int rc ) {
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intf_shutdown ( &hw->xfer, rc );
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process_del ( &hw->process );
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}
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static void hw_step ( struct hw *hw ) {
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int rc;
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if ( xfer_window ( &hw->xfer ) ) {
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rc = xfer_deliver_raw ( &hw->xfer, hw_msg, sizeof ( hw_msg ) );
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hw_finished ( hw, rc );
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}
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}
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static struct interface_operation hw_xfer_operations[] = {
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INTF_OP ( xfer_window_changed, struct hw *, hw_step ),
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INTF_OP ( intf_close, struct hw *, hw_finished ),
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};
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static struct interface_descriptor hw_xfer_desc =
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INTF_DESC ( struct hw, xfer, hw_xfer_operations );
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static struct process_descriptor hw_process_desc =
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PROC_DESC_ONCE ( struct hw, process, hw_step );
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static int hw_open ( struct interface *xfer, struct uri *uri __unused ) {
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struct hw *hw;
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/* Allocate and initialise structure */
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hw = zalloc ( sizeof ( *hw ) );
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if ( ! hw )
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return -ENOMEM;
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ref_init ( &hw->refcnt, NULL );
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intf_init ( &hw->xfer, &hw_xfer_desc, &hw->refcnt );
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process_init ( &hw->process, &hw_process_desc, &hw->refcnt );
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/* Attach parent interface, mortalise self, and return */
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intf_plug_plug ( &hw->xfer, xfer );
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ref_put ( &hw->refcnt );
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return 0;
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}
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struct uri_opener hw_uri_opener __uri_opener = {
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.scheme = "hw",
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.open = hw_open,
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};
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