//========================================================================
// GLFW - An OpenGL framework
// File:        dos_irq.s
// Platform:    DOS
// API version: 2.4
// WWW:         http://glfw.sourceforge.net
//------------------------------------------------------------------------
// Copyright (c) 2002-2004 Camilla Berglund
//
// This software is provided 'as-is', without any express or implied
// warranty. In no event will the authors be held liable for any damages
// arising from the use of this software.
//
// Permission is granted to anyone to use this software for any purpose,
// including commercial applications, and to alter it and redistribute it
// freely, subject to the following restrictions:
//
// 1. The origin of this software must not be misrepresented; you must not
//    claim that you wrote the original software. If you use this software
//    in a product, an acknowledgment in the product documentation would
//    be appreciated but is not required.
//
// 2. Altered source versions must be plainly marked as such, and must not
//    be misrepresented as being the original software.
//
// 3. This notice may not be removed or altered from any source
//    distribution.
//
//========================================================================

                .file   "dos_irq.S"

                .text


#define IRQ_STACK_SIZE  16384

#define IRQ_WRAPPER_LEN (__irq_wrapper_1-__irq_wrapper_0)
#define IRQ_OLD         (__irq_old_0-__irq_wrapper_0)
#define IRQ_HOOK        (__irq_hook_0-__irq_wrapper_0)
#define IRQ_STACK       (__irq_stack_0-__irq_wrapper_0)


//========================================================================
// common
//========================================================================

                .balign 4
common:
                movw    $0x0400, %ax
                int     $0x31

                movl    %ss:8(%ebp), %ebx
                cmpl    $15, %ebx
                jbe     0f
fail:
                orl     $-1, %eax
                popl    %edi
                popl    %ebx
                leave
                ret

        0:
                movl    %ebx, %edi
                imull   $IRQ_WRAPPER_LEN, %edi
                addl    $__irq_wrapper_0, %edi

                cmpb    $7, %bl
                jbe     1f
                movb    %dl, %dh
                subb    $8, %dh
        1:
                addb    %dh, %bl
                ret


//========================================================================
// _glfwInstallDOSIrq()
//========================================================================

                .balign 4
                .global __glfwInstallDOSIrq
__glfwInstallDOSIrq:
                pushl   %ebp
                movl    %esp, %ebp
                pushl   %ebx
                pushl   %edi

                call    common

                cmpl    $0, IRQ_HOOK(%edi)
                jne     fail

                pushl   $IRQ_WRAPPER_LEN
                pushl   %edi
                call    __go32_dpmi_lock_code
                addl    $8, %esp
                testl   %eax, %eax
                jnz     fail

/* OLD >>
                pushl   $IRQ_STACK_SIZE
                call    _pc_malloc
                popl    %edx
                testl   %eax, %eax
                jz      fail
                addl    %edx, %eax
                movl    %eax, IRQ_STACK(%edi)
<< OLD */

/* MG: NEW >> */
                pushl   $IRQ_STACK_SIZE
                call    _malloc
                popl    %edx
                testl   %eax, %eax
                jz      fail

                pushl   %edx
                pushl   %eax
                call    __go32_dpmi_lock_data
                addl    $8, %esp
                testl   %eax, %eax
                jnz     fail
                subl    $8, %esp
                popl    %eax
                popl    %edx

                addl    %edx, %eax
                movl    %eax, IRQ_STACK(%edi)
/* << NEW */

                movl    ___djgpp_ds_alias, %eax
                movl    %eax, IRQ_STACK+4(%edi)

                movl    %ss:12(%ebp), %eax
                movl    %eax, IRQ_HOOK(%edi)

                movw    $0x0204, %ax
                int     $0x31
                movl    %edx, IRQ_OLD(%edi)
                movw    %cx, IRQ_OLD+4(%edi)
                movw    $0x0205, %ax
                movl    %edi, %edx
                movl    %cs, %ecx
                int     $0x31

done:
                xorl    %eax, %eax
                popl    %edi
                popl    %ebx
                leave
                ret


//========================================================================
// _glfwRemoveDOSIrq()
//========================================================================
                .balign 4
                .global __glfwRemoveDOSIrq
__glfwRemoveDOSIrq:
                pushl   %ebp
                movl    %esp, %ebp
                pushl   %ebx
                pushl   %edi

                call    common

                cmpl    $0, IRQ_HOOK(%edi)
                je      fail

                movl    $0, IRQ_HOOK(%edi)

                movw    $0x0205, %ax
                movl    IRQ_OLD(%edi), %edx
                movl    IRQ_OLD+4(%edi), %ecx
                int     $0x31

                movl    IRQ_STACK(%edi), %eax
                subl    $IRQ_STACK_SIZE, %eax
                pushl   %eax
                call    _free
                popl    %eax

                jmp     done


//========================================================================
// IRQ wrapper code for all 16 different IRQs
//========================================================================

#define WRAPPER(x)                                                         ; \
                .balign 4                                                  ; \
__irq_wrapper_##x:                                                         ; \
                pushal                                                     ; \
                pushl   %ds                                                ; \
                pushl   %es                                                ; \
                pushl   %fs                                                ; \
                pushl   %gs                                                ; \
                movl    %ss, %ebx                                          ; \
                movl    %esp, %esi                                         ; \
                lss     %cs:__irq_stack_##x, %esp                          ; \
                pushl   %ss                                                ; \
                pushl   %ss                                                ; \
                popl    %es                                                ; \
                popl    %ds                                                ; \
                movl    ___djgpp_dos_sel, %fs                              ; \
                pushl   %fs                                                ; \
                popl    %gs                                                ; \
                call    *__irq_hook_##x                                    ; \
                movl    %ebx, %ss                                          ; \
                movl    %esi, %esp                                         ; \
                testl   %eax, %eax                                         ; \
                popl    %gs                                                ; \
                popl    %fs                                                ; \
                popl    %es                                                ; \
                popl    %ds                                                ; \
                popal                                                      ; \
                jz      __irq_ignore_##x                                   ; \
__irq_bypass_##x:                                                          ; \
                ljmp    *%cs:__irq_old_##x                                 ; \
__irq_ignore_##x:                                                          ; \
                iret                                                       ; \
                .balign 4                                                  ; \
__irq_old_##x:                                                             ; \
                .long   0, 0                                               ; \
__irq_hook_##x:                                                            ; \
                .long   0                                                  ; \
__irq_stack_##x:                                                           ; \
                .long   0, 0

                WRAPPER(0);
                WRAPPER(1);
                WRAPPER(2);
                WRAPPER(3);
                WRAPPER(4);
                WRAPPER(5);
                WRAPPER(6);
                WRAPPER(7);
                WRAPPER(8);
                WRAPPER(9);
                WRAPPER(10);
                WRAPPER(11);
                WRAPPER(12);
                WRAPPER(13);
                WRAPPER(14);
                WRAPPER(15);