Add a threading syscall API.

zion/include/zcall.h

@@ -7,6 +7,7 @@
 #define ZC_WRITE 0x01
 #define ZC_READ 0x02
 
+// Process Calls.
 #define Z_PROCESS_EXIT 0x01
 #define Z_PROCESS_SPAWN 0x02
 #define Z_PROCESS_START 0x03
@@ -16,10 +17,14 @@
 #define ZC_PROC_SPAWN_PROC 0x100
 #define ZC_PROC_SPAWN_THREAD 0x101
 
+#define Z_INIT_PROC_SELF 0x1
+
+// Thread Calls.
 #define Z_THREAD_CREATE 0x10
 #define Z_THREAD_START 0x11
 #define Z_THREAD_EXIT 0x12
 
+// Debugging Calls.
 #define Z_DEBUG_PRINT 0x10000000
 
 uint64_t ZDebug(const char* message);
@@ -31,5 +36,29 @@ struct ZProcessSpawnElfReq {
   uint64_t elf_size;
 };
 
+// Creates a child process of the current one and
+// starts its root thread from the provided ELF file.
 uint64_t ZProcessSpawnElf(uint64_t cap_id, uint64_t elf_base,
                           uint64_t elf_size);
+
+struct ZThreadCreateReq {
+  uint64_t proc_cap;
+};
+
+struct ZThreadCreateResp {
+  uint64_t thread_cap;
+};
+
+uint64_t ZThreadCreate(uint64_t proc_cap, uint64_t* thread_cap);
+
+struct ZThreadStartReq {
+  uint64_t thread_cap;
+  uint64_t entry;
+  uint64_t arg1;
+  uint64_t arg2;
+};
+
+uint64_t ZThreadStart(uint64_t thread_cap, uint64_t entry, uint64_t arg1,
+                      uint64_t arg2);
+
+void ZThreadExit();