1/* -----------------------------------------------------------------------
2   win32.S - Copyright (c) 1996, 1998, 2001, 2002  Red Hat, Inc.
3	     Copyright (c) 2001  John Beniton
4	     Copyright (c) 2002  Ranjit Mathew
5
6
7   X86 Foreign Function Interface
8
9   Permission is hereby granted, free of charge, to any person obtaining
10   a copy of this software and associated documentation files (the
11   ``Software''), to deal in the Software without restriction, including
12   without limitation the rights to use, copy, modify, merge, publish,
13   distribute, sublicense, and/or sell copies of the Software, and to
14   permit persons to whom the Software is furnished to do so, subject to
15   the following conditions:
16
17   The above copyright notice and this permission notice shall be included
18   in all copies or substantial portions of the Software.
19
20   THE SOFTWARE IS PROVIDED ``AS IS'', WITHOUT WARRANTY OF ANY KIND, EXPRESS
21   OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
22   MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
23   IN NO EVENT SHALL CYGNUS SOLUTIONS BE LIABLE FOR ANY CLAIM, DAMAGES OR
24   OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
25   ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
26   OTHER DEALINGS IN THE SOFTWARE.
27   ----------------------------------------------------------------------- */
28
29/* theller: almost verbatim translation from gas syntax to MSVC inline
30   assembler code. */
31
32/* theller: ffi_call_x86 now returns an integer - the difference of the stack
33   pointer before and after the function call.  If everything is ok, zero is
34   returned.  If stdcall functions are passed the wrong number of arguments,
35   the difference will be nonzero. */
36
37#include <ffi.h>
38#include <ffi_common.h>
39
40__declspec(naked) int
41ffi_call_x86(void (* prepfunc)(char *, extended_cif *), /* 8 */
42	     extended_cif *ecif, /* 12 */
43	     unsigned bytes, /* 16 */
44	     unsigned flags, /* 20 */
45	     unsigned *rvalue, /* 24 */
46	     void (*fn)()) /* 28 */
47{
48	_asm {
49		push ebp
50		mov ebp, esp
51
52		push esi // NEW: this register must be preserved across function calls
53// XXX SAVE ESP NOW!
54		mov esi, esp		// save stack pointer before the call
55
56// Make room for all of the new args.
57		mov ecx, [ebp+16]
58		sub esp, ecx		// sub esp, bytes
59
60		mov eax, esp
61
62// Place all of the ffi_prep_args in position
63		push [ebp + 12] // ecif
64		push eax
65		call [ebp + 8] // prepfunc
66
67// Return stack to previous state and call the function
68		add esp, 8
69// FIXME: Align the stack to a 128-bit boundary to avoid
70// potential performance hits.
71		call [ebp + 28]
72
73// Load ecif->cif->abi
74		mov ecx, [ebp + 12]
75		mov ecx, [ecx]ecif.cif
76		mov ecx, [ecx]ecif.cif.abi
77
78		cmp ecx, FFI_STDCALL
79		je noclean
80// STDCALL: Remove the space we pushed for the args
81		mov ecx, [ebp + 16]
82		add esp, ecx
83// CDECL: Caller has already cleaned the stack
84noclean:
85// Check that esp has the same value as before!
86		sub esi, esp
87
88// Load %ecx with the return type code
89		mov ecx, [ebp + 20]
90
91// If the return value pointer is NULL, assume no return value.
92/*
93  Intel asm is weird. We have to explicitely specify 'DWORD PTR' in the nexr instruction,
94  otherwise only one BYTE will be compared (instead of a DWORD)!
95 */
96		cmp DWORD PTR [ebp + 24], 0
97		jne sc_retint
98
99// Even if there is no space for the return value, we are
100// obliged to handle floating-point values.
101		cmp ecx, FFI_TYPE_FLOAT
102		jne sc_noretval
103//        fstp  %st(0)
104		fstp st(0)
105
106		jmp sc_epilogue
107
108sc_retint:
109		cmp ecx, FFI_TYPE_INT
110		jne sc_retfloat
111//        # Load %ecx with the pointer to storage for the return value
112		mov ecx, [ebp + 24]
113		mov [ecx + 0], eax
114		jmp sc_epilogue
115
116sc_retfloat:
117		cmp ecx, FFI_TYPE_FLOAT
118		jne sc_retdouble
119// Load %ecx with the pointer to storage for the return value
120		mov ecx, [ebp+24]
121//        fstps (%ecx)
122		fstp DWORD PTR [ecx]
123		jmp sc_epilogue
124
125sc_retdouble:
126		cmp ecx, FFI_TYPE_DOUBLE
127		jne sc_retlongdouble
128//        movl  24(%ebp),%ecx
129		mov ecx, [ebp+24]
130		fstp QWORD PTR [ecx]
131		jmp sc_epilogue
132
133		jmp sc_retlongdouble // avoid warning about unused label
134sc_retlongdouble:
135		cmp ecx, FFI_TYPE_LONGDOUBLE
136		jne sc_retint64
137// Load %ecx with the pointer to storage for the return value
138		mov ecx, [ebp+24]
139//        fstpt (%ecx)
140		fstp QWORD PTR [ecx] /* XXX ??? */
141		jmp sc_epilogue
142
143sc_retint64:
144		cmp ecx, FFI_TYPE_SINT64
145		jne sc_retstruct
146// Load %ecx with the pointer to storage for the return value
147		mov ecx, [ebp+24]
148		mov [ecx+0], eax
149		mov [ecx+4], edx
150
151sc_retstruct:
152// Nothing to do!
153
154sc_noretval:
155sc_epilogue:
156		mov eax, esi
157		pop esi // NEW restore: must be preserved across function calls
158		mov esp, ebp
159		pop ebp
160		ret
161	}
162}
163