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// Macros for entering C code
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// Copyright (C) 2008,2009 Kevin O'Connor <kevin@koconnor.net>
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// This file may be distributed under the terms of the GNU LGPLv3 license.
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/****************************************************************
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****************************************************************/
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// Call a C function - this does the minimal work necessary to
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// call into C. It sets up %ds, backs up %es, and backs up
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// those registers that are call clobbered by the C compiler.
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cli // In case something far-calls instead of using "int"
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pushl %eax // Save registers clobbered by C code
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movw %ss, %ax // Move %ss to %ds
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pushl %esp // Backup %esp, then clear high bits
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popl %esp // Restore %esp (including high bits)
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popw %ds // Restore registers saved above
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// As above, but get calling function from stack.
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movw %ss, %cx // Move %ss to %ds
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pushl %esp // Backup %esp, then clear high bits
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movl 16(%esp), %ecx // Get calling function
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movl %eax, 16(%esp) // Save %eax
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popl %esp // Restore %esp (including high bits)
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popw %ds // Restore registers saved above
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// Call a C function with current register list as an
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// argument. This backs up the registers and sets %eax
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// to point to the backup. On return, the registers are
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// restored from the structure.
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.macro ENTRY_ARG cfunc
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pushl %eax // Save registers (matches struct bregs)
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movw %ss, %ax // Move %ss to %ds
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movl %esp, %ebx // Backup %esp, then zero high bits
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movl %esp, %eax // First arg is pointer to struct bregs
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movl %ebx, %esp // Restore %esp (including high bits)
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popw %ds // Restore registers (from struct bregs)
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// As above, but get calling function from stack.
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movw %ss, %cx // Move %ss to %ds
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movl %esp, %ebx // Backup %esp, then zero high bits
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movl 28(%esp), %ecx // Get calling function
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movl %eax, 28(%esp) // Save %eax
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movl %esp, %eax // First arg is pointer to struct bregs
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movl %ebx, %esp // Restore %esp (including high bits)
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popw %ds // Restore registers (from struct bregs)
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// Same as ENTRY_ARG, but don't mangle %esp
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.macro ENTRY_ARG_ESP cfunc
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pushl %eax // Save registers (matches struct bregs)
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movw %ss, %ax // Move %ss to %ds
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movl %esp, %eax // First arg is pointer to struct bregs
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popw %ds // Restore registers (from struct bregs)
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// Reset stack, transition to 32bit mode, and call a C function.
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.macro ENTRY_INTO32 cfunc
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movl $ BUILD_STACK_ADDR , %esp
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// Declare a function
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.section .text.asm.\func
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// Declare an exported function
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.macro EXPORTFUNC func
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.section .text.asm.export.\func
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src/entryfuncs.S
