--- /dev/null
+#ifndef _IPXE_PROCESS_H
+#define _IPXE_PROCESS_H
+
+/** @file
+ *
+ * Processes
+ *
+ */
+
+FILE_LICENCE ( GPL2_OR_LATER );
+
+#include <ipxe/list.h>
+#include <ipxe/refcnt.h>
+#include <ipxe/tables.h>
+
+/** A process */
+struct process {
+ /** List of processes */
+ struct list_head list;
+ /** Process descriptor */
+ struct process_descriptor *desc;
+ /** Reference counter
+ *
+ * If this process is not part of a reference-counted object,
+ * this field may be NULL.
+ */
+ struct refcnt *refcnt;
+};
+
+/** A process descriptor */
+struct process_descriptor {
+ /** Offset of process within containing object */
+ size_t offset;
+ /**
+ * Single-step the process
+ *
+ * This method should execute a single step of the process.
+ * Returning from this method is isomorphic to yielding the
+ * CPU to another process.
+ */
+ void ( * step ) ( void *object );
+ /** Automatically reschedule the process */
+ int reschedule;
+};
+
+/**
+ * Define a process step() method
+ *
+ * @v object_type Implementing method's expected object type
+ * @v step Implementing method
+ * @ret step Process step method
+ */
+#define PROC_STEP( object_type, step ) \
+ ( ( ( ( typeof ( step ) * ) NULL ) == \
+ ( ( void ( * ) ( object_type *object ) ) NULL ) ) ? \
+ ( void ( * ) ( void *object ) ) step : \
+ ( void ( * ) ( void *object ) ) step )
+
+/**
+ * Calculate offset of process within containing object
+ *
+ * @v object_type Containing object data type
+ * @v name Process name (i.e. field within object data type)
+ * @ret offset Offset of process within containing object
+ */
+#define process_offset( object_type, name ) \
+ ( ( ( ( typeof ( ( ( object_type * ) NULL )->name ) * ) NULL ) \
+ == ( ( struct process * ) NULL ) ) \
+ ? offsetof ( object_type, name ) \
+ : offsetof ( object_type, name ) )
+
+/**
+ * Define a process descriptor
+ *
+ * @v object_type Containing object data type
+ * @v process Process name (i.e. field within object data type)
+ * @v step Process' step() method
+ * @ret desc Object interface descriptor
+ */
+#define PROC_DESC( object_type, process, _step ) { \
+ .offset = process_offset ( object_type, process ), \
+ .step = PROC_STEP ( object_type, _step ), \
+ .reschedule = 1, \
+ }
+
+/**
+ * Define a process descriptor for a process that runs only once
+ *
+ * @v object_type Containing object data type
+ * @v process Process name (i.e. field within object data type)
+ * @v step Process' step() method
+ * @ret desc Object interface descriptor
+ */
+#define PROC_DESC_ONCE( object_type, process, _step ) { \
+ .offset = process_offset ( object_type, process ), \
+ .step = PROC_STEP ( object_type, _step ), \
+ .reschedule = 0, \
+ }
+
+/**
+ * Define a process descriptor for a pure process
+ *
+ * A pure process is a process that does not have a containing object.
+ *
+ * @v step Process' step() method
+ * @ret desc Object interface descriptor
+ */
+#define PROC_DESC_PURE( _step ) { \
+ .offset = 0, \
+ .step = PROC_STEP ( struct process, _step ), \
+ .reschedule = 1, \
+ }
+
+extern void * __attribute__ (( pure ))
+process_object ( struct process *process );
+extern void process_add ( struct process *process );
+extern void process_del ( struct process *process );
+extern void step ( void );
+
+/**
+ * Initialise process without adding to process list
+ *
+ * @v process Process
+ * @v desc Process descriptor
+ * @v refcnt Containing object reference count, or NULL
+ */
+static inline __attribute__ (( always_inline )) void
+process_init_stopped ( struct process *process,
+ struct process_descriptor *desc,
+ struct refcnt *refcnt ) {
+ INIT_LIST_HEAD ( &process->list );
+ process->desc = desc;
+ process->refcnt = refcnt;
+}
+
+/**
+ * Initialise process and add to process list
+ *
+ * @v process Process
+ * @v desc Process descriptor
+ * @v refcnt Containing object reference count, or NULL
+ */
+static inline __attribute__ (( always_inline )) void
+process_init ( struct process *process,
+ struct process_descriptor *desc,
+ struct refcnt *refcnt ) {
+ process_init_stopped ( process, desc, refcnt );
+ process_add ( process );
+}
+
+/**
+ * Check if process is running
+ *
+ * @v process Process
+ * @ret running Process is running
+ */
+static inline __attribute__ (( always_inline )) int
+process_running ( struct process *process ) {
+ return ( ! list_empty ( &process->list ) );
+}
+
+/** Permanent process table */
+#define PERMANENT_PROCESSES __table ( struct process, "processes" )
+
+/**
+ * Declare a permanent process
+ *
+ * Permanent processes will be automatically added to the process list
+ * at initialisation time.
+ */
+#define __permanent_process __table_entry ( PERMANENT_PROCESSES, 01 )
+
+/** Define a permanent process
+ *
+ */
+#define PERMANENT_PROCESS( name, step ) \
+static struct process_descriptor name ## _desc = PROC_DESC_PURE ( step ); \
+struct process name __permanent_process = { \
+ .list = LIST_HEAD_INIT ( name.list ), \
+ .desc = & name ## _desc, \
+ .refcnt = NULL, \
+};
+
+/**
+ * Find debugging colourisation for a process
+ *
+ * @v process Process
+ * @ret col Debugging colourisation
+ *
+ * Use as the first argument to DBGC() or equivalent macro.
+ */
+#define PROC_COL( process ) process_object ( process )
+
+/** printf() format string for PROC_DBG() */
+#define PROC_FMT "%p+%zx"
+
+/**
+ * printf() arguments for representing a process
+ *
+ * @v process Process
+ * @ret args printf() argument list corresponding to PROC_FMT
+ */
+#define PROC_DBG( process ) process_object ( process ), (process)->desc->offset
+
+#endif /* _IPXE_PROCESS_H */
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