code review 4926042: runtime: use cgo runtime functions to call windows syscalls

src/pkg/runtime/windows/386/sys.s

 // Copyright 2009 The Go Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
 #include "386/asm.h"
 
-// void *stdcall_raw(void *fn, int32 count, uintptr *args)
-TEXT runtime·stdcall_raw(SB),7,$0
-        // Copy arguments from stack.
-        MOVL    fn+0(FP), AX
-        MOVL    count+4(FP), CX         // words
-        MOVL    args+8(FP), BP
+// void runtime·asmstdcall(WinCall *c);
+TEXT runtime·asmstdcall(SB),7,$0
+        MOVL    c+0(FP), DX
 
-        // Switch to m->g0 if needed.
-        get_tls(DI)
-        MOVL    m(DI), DX
-        MOVL    m_g0(DX), SI
-        CMPL    g(DI), SI
-        MOVL    SP, BX
-        JEQ     2(PC)
-        MOVL    (g_sched+gobuf_sp)(SI), SP
-        PUSHL   BX
-        PUSHL   g(DI)
-        MOVL    SI, g(DI)
+        // SetLastError(0).
+        MOVL    $0, 0x34(FS)
 
-        // Copy args to new stack.
+        // Copy args to the stack.
+        MOVL    (wincall_n)(DX), CX     // words

[rsc, 2011/08/26 20:20:26]

Are the parens around (wincall_n) necessary?
If not, please remove throughout.

[brainman, 2011/08/27 13:17:09]

Done.

         MOVL    CX, BX
         SALL    $2, BX
         SUBL    BX, SP                  // room for args
         MOVL    SP, DI
-        MOVL    BP, SI
+        MOVL    (wincall_args)(DX), SI
         CLD
         REP; MOVSL
 
         // Call stdcall function.
+        MOVL    (wincall_fn)(DX), AX
         CALL    AX
 
-        // Restore original SP, g.
-        get_tls(DI)
-        POPL    g(DI)
-        POPL    SP
+        // Return result.
+        MOVL    c+0(FP), DX
+        MOVL    AX, (wincall_r)(DX)
 
-        // Someday the convention will be D is always cleared.
-        CLD
+        // GetLastError().
+        MOVL    0x34(FS), BX
+        MOVL    BX, (wincall_err)(DX)
 
         RET
 
 // faster get/set last error
 TEXT runtime·getlasterror(SB),7,$0
         MOVL    0x34(FS), AX
         RET
 
 TEXT runtime·setlasterror(SB),7,$0
         MOVL    err+0(FP), AX
@@ skipping 192 matching lines @@
 
         XORL    AX, AX                  // return 0 == success
 
         RET
 
 // setldt(int entry, int address, int limit)
 TEXT runtime·setldt(SB),7,$0
         MOVL    address+4(FP), CX
         MOVL    CX, 0x2c(FS)
         RET