66 lines
2.0 KiB
ArmAsm
66 lines
2.0 KiB
ArmAsm
/*******************************************************************************
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Copyright(C) Jonas 'Sortie' Termansen 2013.
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This file is part of the Sortix C Library.
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The Sortix C Library is free software: you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation, either version 3 of the License, or (at your
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option) any later version.
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The Sortix C Library is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
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License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with the Sortix C Library. If not, see <http://www.gnu.org/licenses/>.
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x86/syscall.s
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Function for performing system calls.
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*******************************************************************************/
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# i386 system call conventions:
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# interrupt 128
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# system call number: %eax
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# parameters: %ebx, %ecx, %edx, %edi, %esi
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# return value: %eax, %edx
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# return errno: %ecx
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# clobbered: %ebx, %edi, %esi
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# preserved: %ebp, %esp
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.section .text
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.global asm_syscall
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asm_syscall: /* syscall num in %eax. */
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push %ebp
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mov %esp, %ebp
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push %ebx
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push %edi
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push %esi
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# 0 (%ebp) # saved_ebp
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# 4 (%ebp) # return_eip
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mov 8 (%ebp), %ebx # param_word1
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mov 12(%ebp), %ecx # param_word2
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mov 16(%ebp), %edx # param_word3
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mov 20(%ebp), %edi # param_word4
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mov 24(%ebp), %esi # param_word5
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int $0x80
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test %ecx, %ecx # ret_errno & ret_errno
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jz 1f # if ( !(ret_errno & ret_errno) )
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mov %eax, %ebx # preserve: ret_low
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mov %edx, %edi # preserve: ret_high
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mov %ecx, %esi # preserve: ret_errno
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call get_errno_location # get_errno_location()
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mov %esi, (%eax) # *get_errno_location() = ret_errno
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mov %ebx, %eax # restore: ret_low
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mov %edi, %edx # restore: ret_high
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1:
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pop %esi
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pop %edi
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pop %ebx
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pop %ebp
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ret
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.size asm_syscall, .-asm_syscall
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