--- /dev/null
+// Macros for entering C code
+//
+// Copyright (C) 2008,2009 Kevin O'Connor <kevin@koconnor.net>
+//
+// This file may be distributed under the terms of the GNU LGPLv3 license.
+
+
+/****************************************************************
+ * 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
+
+ // As above, but get calling function from stack.
+ .macro ENTRY_ST
+ cli
+ cld
+ pushl %ecx
+ pushl %edx
+ pushw %es
+ pushw %ds
+ movw %ss, %cx // Move %ss to %ds
+ movw %cx, %ds
+ pushl %esp // Backup %esp, then clear high bits
+ movzwl %sp, %esp
+ movl 16(%esp), %ecx // Get calling function
+ movl %eax, 16(%esp) // Save %eax
+ calll *%ecx
+ 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
+ pushl %eax // Save registers (matches struct bregs)
+ pushl %ecx
+ pushl %edx
+ pushl %ebx
+ pushl %ebp
+ pushl %esi
+ pushl %edi
+ pushw %es
+ pushw %ds
+ 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)
+ popw %ds // Restore registers (from struct bregs)
+ popw %es
+ popl %edi
+ popl %esi
+ popl %ebp
+ popl %ebx
+ popl %edx
+ popl %ecx
+ popl %eax
+ .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)
+ popw %ds // Restore registers (from struct bregs)
+ popw %es
+ popl %edi
+ popl %esi
+ popl %ebp
+ popl %ebx
+ popl %edx
+ popl %ecx
+ popl %eax
+ .endm
+
+ // Same as ENTRY_ARG, but don't mangle %esp
+ .macro ENTRY_ARG_ESP cfunc
+ cli
+ cld
+ pushl %eax // Save registers (matches struct bregs)
+ pushl %ecx
+ pushl %edx
+ pushl %ebx
+ pushl %ebp
+ pushl %esi
+ pushl %edi
+ pushw %es
+ pushw %ds
+ movw %ss, %ax // Move %ss to %ds
+ movw %ax, %ds
+ movl %esp, %eax // First arg is pointer to struct bregs
+ calll \cfunc
+ popw %ds // Restore registers (from struct bregs)
+ popw %es
+ popl %edi
+ popl %esi
+ popl %ebp
+ popl %ebx
+ popl %edx
+ popl %ecx
+ popl %eax
+ .endm
+
+ // Reset stack, transition to 32bit mode, and call a C function.
+ // Clobbers %ax
+ .macro ENTRY_INTO32 cfunc
+ xorw %ax, %ax
+ movw %ax, %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
+
+ // Declare an exported function
+ .macro EXPORTFUNC func
+ .section .text.asm.export.\func
+ .global \func
+ .endm
