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// Macros for entering C code
//
// Copyright (C) 2008-2014 Kevin O'Connor <kevin@koconnor.net>
//
// This file may be distributed under the terms of the GNU LGPLv3 license.
/****************************************************************
* Macros for save and restore of 'struct bregs' registers
****************************************************************/
#define PUSHBREGS_size 32
// Save registers (matches struct bregs) to stack
.macro PUSHBREGS
pushl %eax
pushl %ecx
pushl %edx
pushl %ebx
pushl %ebp
pushl %esi
pushl %edi
pushw %es
pushw %ds
.endm
// Restore registers (from struct bregs) from stack
.macro POPBREGS
popw %ds
popw %es
popl %edi
popl %esi
popl %ebp
popl %ebx
popl %edx
popl %ecx
popl %eax
.endm
// Save registers to struct bregs at %ds:%eax. The caller
// should "pushw %ds ; pushl %eax" prior to calling - this macro
// will pop them off.
.macro SAVEBREGS_POP_DSEAX
popl BREGS_eax(%eax)
popw BREGS_ds(%eax)
movl %edi, BREGS_edi(%eax)
movl %esi, BREGS_esi(%eax)
movl %ebp, BREGS_ebp(%eax)
movl %ebx, BREGS_ebx(%eax)
movl %edx, BREGS_edx(%eax)
movl %ecx, BREGS_ecx(%eax)
movw %es, BREGS_es(%eax)
.endm
// Restore registers from struct bregs at %ds:%eax
.macro RESTOREBREGS_DSEAX
movl BREGS_edi(%eax), %edi
movl BREGS_esi(%eax), %esi
movl BREGS_ebp(%eax), %ebp
movl BREGS_ebx(%eax), %ebx
movl BREGS_edx(%eax), %edx
movl BREGS_ecx(%eax), %ecx
movw BREGS_es(%eax), %es
pushl BREGS_eax(%eax)
movw BREGS_ds(%eax), %ds
popl %eax
.endm
/****************************************************************
* Entry macros
****************************************************************/
// Call a C function - this does the minimal work necessary to
// call into C. It sets up %ds, backs up %es, and backs up
// those registers that are call clobbered by the C compiler.
.macro ENTRY cfunc
cli // In case something far-calls instead of using "int"
cld
pushl %eax // Save registers clobbered by C code
pushl %ecx
pushl %edx
pushw %es
pushw %ds
movw %ss, %ax // Move %ss to %ds
movw %ax, %ds
pushl %esp // Backup %esp, then clear high bits
movzwl %sp, %esp
calll \cfunc
popl %esp // Restore %esp (including high bits)
popw %ds // Restore registers saved above
popw %es
popl %edx
popl %ecx
popl %eax
.endm
// Call a C function with current register list as an
// argument. This backs up the registers and sets %eax
// to point to the backup. On return, the registers are
// restored from the structure.
.macro ENTRY_ARG cfunc
cli
cld
PUSHBREGS
movw %ss, %ax // Move %ss to %ds
movw %ax, %ds
movl %esp, %ebx // Backup %esp, then zero high bits
movzwl %sp, %esp
movl %esp, %eax // First arg is pointer to struct bregs
calll \cfunc
movl %ebx, %esp // Restore %esp (including high bits)
POPBREGS
.endm
// As above, but get calling function from stack.
.macro ENTRY_ARG_ST
cli
cld
pushl %ecx
pushl %edx
pushl %ebx
pushl %ebp
pushl %esi
pushl %edi
pushw %es
pushw %ds
movw %ss, %cx // Move %ss to %ds
movw %cx, %ds
movl %esp, %ebx // Backup %esp, then zero high bits
movzwl %sp, %esp
movl 28(%esp), %ecx // Get calling function
movl %eax, 28(%esp) // Save %eax
movl %esp, %eax // First arg is pointer to struct bregs
calll *%ecx
movl %ebx, %esp // Restore %esp (including high bits)
POPBREGS
.endm
// Same as ENTRY_ARG, but don't mangle %esp
.macro ENTRY_ARG_ESP cfunc
cli
cld
PUSHBREGS
movw %ss, %ax // Move %ss to %ds
movw %ax, %ds
movl %esp, %eax // First arg is pointer to struct bregs
calll \cfunc
POPBREGS
.endm
// Reset stack, transition to 32bit mode, and call a C function.
.macro ENTRY_INTO32 cfunc
xorw %dx, %dx
movw %dx, %ss
movl $ BUILD_STACK_ADDR , %esp
movl $ \cfunc , %edx
jmp transition32
.endm
// Declare a function
.macro DECLFUNC func
.section .text.asm.\func
.global \func
.endm
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