[project] Generate syscalls from new interface DSL

This change adds a new interface DSL for specifying objects (with
methods) and interfaces (that expose objects, and optionally have their
own methods).

Significant changes:

- Add the new scripts/definitions Python module to parse the DSL
- Add the new definitions directory containing DSL definition files
- Use cog to generate syscall-related code in kernel and libj6
- Unify ordering of pointer + length pairs in interfaces

src/libraries/j6/include/j6/syscalls.h

@@ -1,15 +0,0 @@
-#pragma once
-
-#include <j6/types.h>
-
-#ifdef __cplusplus
-extern "C" {
-#endif
-
-#define SYSCALL(n, name, ...) j6_status_t j6_ ## name (__VA_ARGS__);
-#include "j6/tables/syscalls.inc"
-#undef SYSCALL
-
-#ifdef __cplusplus
-}
-#endif

src/libraries/j6/include/j6/syscalls.h.cog

@@ -0,0 +1,39 @@
+#pragma once
+// vim: ft=cpp
+
+#include <j6/types.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/*[[[cog code generation
+from definitions.context import Context
+
+ctx = Context(definitions_path)
+ctx.parse("syscalls.def")
+syscalls = ctx.interfaces["syscalls"]
+
+for id, scope, method in syscalls.methods:
+    if scope:
+        name = f"{scope.name}_{method.name}"
+    else:
+        name = method.name
+
+    args = []
+    if method.constructor:
+        args.append("j6_handle_t *handle")
+    elif not method.static:
+        args.append("j6_handle_t handle")
+
+    for param in method.params:
+        for type, suffix in param.type.c_names(param.options):
+            args.append(f"{type} {param.name}{suffix}")
+
+    cog.outl(f"""j6_status_t j6_{name} ({", ".join(args)});""")
+]]]*/
+/// [[[end]]]
+
+#ifdef __cplusplus
+}
+#endif

src/libraries/j6/j6.module

@@ -1,9 +1,14 @@
 # vim: ft=python
 
-module("j6",
+j6 = module("j6",
     kind = "lib",
     includes = [ "include" ],
     sources = [
         "init.cpp",
-        "syscalls.s",
     ])
+
+from glob import glob
+definitions = glob('definitions/**/*.def', recursive=True)
+j6.add_input("include/j6/syscalls.h.cog", deps=definitions)
+j6.add_input("syscalls.s.cog", deps=definitions)
+

src/libraries/j6/syscalls.s

@@ -1,28 +0,0 @@
-%macro SYSCALL 2
-	global j6_%1
-	j6_%1:
-		push rbp
-		mov rbp, rsp
-
-		; args should already be in rdi, etc, but rcx will
-		; get stomped, so stash it in r10, which isn't a
-		; callee-saved register, but also isn't used in the
-		; function call ABI.
-		mov r10, rcx
-
-		mov rax, %2
-		syscall
-		; result is now already in rax, so just return
-
-		pop rbp
-		ret
-%endmacro
-
-%define SYSCALL(n, name) SYSCALL name, n
-%define SYSCALL(n, name, a) SYSCALL name, n
-%define SYSCALL(n, name, a, b) SYSCALL name, n
-%define SYSCALL(n, name, a, b, c) SYSCALL name, n
-%define SYSCALL(n, name, a, b, c, d) SYSCALL name, n
-%define SYSCALL(n, name, a, b, c, d, e) SYSCALL name, n
-
-%include "j6/tables/syscalls.inc"

src/libraries/j6/syscalls.s.cog

@@ -0,0 +1,37 @@
+; vim: ft=asm
+
+%macro define_syscall 2
+    global j6_%1
+    j6_%1:
+        push rbp
+        mov rbp, rsp
+
+        ; args should already be in rdi, etc, but rcx will
+        ; get stomped, so stash it in r10, which isn't a
+        ; callee-saved register, but also isn't used in the
+        ; function call ABI.
+        mov r10, rcx
+
+        mov rax, %2
+        syscall
+        ; result is now already in rax, so just return
+
+        pop rbp
+        ret
+%endmacro
+
+; [[[cog code generation
+;   from definitions.context import Context
+;
+;   ctx = Context(definitions_path)
+;   ctx.parse("syscalls.def")
+;   syscalls = ctx.interfaces['syscalls']
+;
+;   for id, scope, method in syscalls.methods:
+;       if scope:
+;           name = f"{scope.name}_{method.name}"
+;       else:
+;           name = method.name
+;       cog.outl(f"define_syscall {name:20}, {id}")
+; ]]]
+; [[[end]]]