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#
# Copyright (C) 2001-2004 Jakub Jermar
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
#
# - Redistributions of source code must retain the above copyright
#   notice, this list of conditions and the following disclaimer.
# - Redistributions in binary form must reproduce the above copyright
#   notice, this list of conditions and the following disclaimer in the
#   documentation and/or other materials provided with the distribution.
# - The name of the author may not be used to endorse or promote products
#   derived from this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
# IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
# OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
# IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
# NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
# THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#

## very low and hardware-level functions

#  Mask for interrupts 0 - 31 (bits 0 - 31) where 0 means that int has no error word
# and 1 means interrupt with error word
#define ERROR_WORD_INTERRUPT_LIST 0x00027D00

.text

.global paging_on
.global enable_l_apic_in_msr
.global interrupt_handlers
.global memcpy
.global memsetb
.global memsetw
.global memcmp


## Turn paging on
#
# Enable paging and write-back caching in CR0.
#
paging_on:
    movl %cr0,%edx
    orl $(1<<31),%edx       # paging on
    andl $~((1<<30)|(1<<29)),%edx   # clear Cache Disable and not Write Though
    movl %edx,%cr0
    jmp 0f
0:
    ret


## Enable local APIC
#
# Enable local APIC in MSR.
#
enable_l_apic_in_msr:
    push %eax

    movl $0x1b, %ecx
    rdmsr
    orl $(1<<11),%eax
    orl $(0xfee00000),%eax
    wrmsr

    pop %eax
    ret


## Declare interrupt handlers
#
# Declare interrupt handlers for n interrupt
# vectors starting at vector i.
#
# The handlers setup data segment registers
# and call trap_dispatcher().
#
.macro handler i n
    push %ebp
    movl %esp,%ebp
    pusha

    push %ds
    push %es

    # we must fill the data segment registers
    movw $16,%ax
    movw %ax,%ds
    movw %ax,%es

    movl $(\i),%edi
    pushl %ebp
    addl $4,(%esp)
    pushl %edi
    call trap_dispatcher
    addl $8,%esp

    pop %es
    pop %ds


# CLNT
    pushfl
    pop %eax
    and $0xFFFFBFFF,%eax
    push %eax
    popfl
    


# Test if this is interrupt with error word or not
    mov $\i,%cl
    movl $1,%eax
    test $0xe0,%cl
    jnz 0f
    and $0x1f,%cl
    shl %cl,%eax
    and $ERROR_WORD_INTERRUPT_LIST,%eax
    jz 0f


# Return with error word
    popa
    pop %ebp
    add $4,%esp # Skip error word
    iret

0:
# Return with no error word
    popa
    pop %ebp
    iret

    .if (\n-\i)-1
    handler "(\i+1)",\n
    .endif
.endm

# keep in sync with pm.h !!!
IDT_ITEMS=64
interrupt_handlers:
h_start:
    handler 0 64
#   handler 64 128  
#   handler 128 192
#   handler 192 256
h_end:


## Copy memory
#
# Copy a given number of bytes (3rd argument)
# from the memory location defined by 2nd argument
# to the memory location defined by 1st argument.
# The memory areas cannot overlap.
#
SRC=16
DST=12
CNT=20
memcpy:
    push %esi
    push %edi

    movl CNT(%esp),%ecx
    movl DST(%esp),%edi
    movl SRC(%esp),%esi

    rep movsb %ds:(%esi),%es:(%edi)

    pop %edi
    pop %esi
    ret


## Fill memory with bytes
#
# Fill a given number of bytes (2nd argument)
# at memory defined by 1st argument with the
# byte value defined by 3rd argument.
#
DST=12
CNT=16
X=20
memsetb:
    push %eax
    push %edi

    movl CNT(%esp),%ecx
    movl DST(%esp),%edi
    movl X(%esp),%eax

    rep stosb %al,%es:(%edi)

    pop %edi
    pop %eax
    ret


## Fill memory with words
#
# Fill a given number of words (2nd argument)
# at memory defined by 1st argument with the
# word value defined by 3rd argument.
#
DST=12
CNT=16
X=20
memsetw:
    push %eax
    push %edi

    movl CNT(%esp),%ecx
    movl DST(%esp),%edi
    movl X(%esp),%eax

    rep stosw %ax,%es:(%edi)

    pop %edi
    pop %eax

    ret


## Compare memory regions for equality
#
# Compare a given number of bytes (3rd argument)
# at memory locations defined by 1st and 2nd argument
# for equality. If the bytes are equal, EAX contains
# 0.
#
SRC=12
DST=16
CNT=20
memcmp:
    push %esi
    push %edi

    movl CNT(%esp),%ecx
    movl DST(%esp),%edi
    movl SRC(%esp),%esi

    repe cmpsb %es:(%edi),%ds:(%esi)
    movl %ecx,%eax      # %ecx contains the return value (zero on success)

    pop %edi
    pop %esi
    
    ret


# THIS IS USERSPACE CODE
.global utext
utext:
    xor %ax,%ax
    mov %ax,%ds
    mov %ax,%es
    mov %ax,%fs
    mov %ax,%gs
0:
    int $48
    jmp 0b
    # not reached
utext_end:

.data
.global utext_size
utext_size:
    .long utext_end - utext 

.global interrupt_handler_size

interrupt_handler_size: .long (h_end-h_start)/IDT_ITEMS