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1// Copyright 2019 The Marl Authors.
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7//     https://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15#if defined(__i386__)
16
17#define MARL_BUILD_ASM 1
18#include "osfiber_asm_x86.h"
19
20// void marl_fiber_swap(marl_fiber_context* from, const marl_fiber_context* to)
21// esp+4: from
22// esp+8: to
23.text
24.global marl_fiber_swap
25.align 4
26marl_fiber_swap:
27    // Save context 'from'
28    movl        4(%esp), %eax
29
30    // Store callee-preserved registers
31    movl        %ebx, MARL_REG_EBX(%eax)
32    movl        %ebp, MARL_REG_EBP(%eax)
33    movl        %esi, MARL_REG_ESI(%eax)
34    movl        %edi, MARL_REG_EDI(%eax)
35
36    movl        (%esp), %ecx             /* call stores the return address on the stack before jumping */
37    movl        %ecx, MARL_REG_EIP(%eax)
38    lea         4(%esp), %ecx            /* skip the pushed return address */
39    movl        %ecx, MARL_REG_ESP(%eax)
40
41    // Load context 'to'
42    movl        8(%esp), %ecx
43
44    // Load callee-preserved registers
45    movl        MARL_REG_EBX(%ecx), %ebx
46    movl        MARL_REG_EBP(%ecx), %ebp
47    movl        MARL_REG_ESI(%ecx), %esi
48    movl        MARL_REG_EDI(%ecx), %edi
49
50    // Load stack pointer
51    movl        MARL_REG_ESP(%ecx), %esp
52
53    // Load instruction pointer, and jump
54    movl        MARL_REG_EIP(%ecx), %ecx
55    jmp         *%ecx
56
57#endif // defined(__i386__)
58