//----------------------------------------------------------------------------//
//                                OS on Kaleid                                //
//                                                                            //
//  Desc:  System call & userspace related functions                          //
//                                                                            //
//                                                                            //
//  Copyright © 2018-2021 The OS/K Team                                       //
//                                                                            //
//  This file is part of OS/K.                                                //
//                                                                            //
//  OS/K is free software: you can redistribute it and/or modify              //
//  it under the terms of the GNU General Public License as published by      //
//  the Free Software Foundation, either version 3 of the License, or         //
//  any later version.                                                        //
//                                                                            //
//  OS/K is distributed in the hope that it will be useful,                   //
//  but WITHOUT ANY WARRANTY//without even the implied warranty of            //
//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the             //
//  GNU General Public License for more details.                              //
//                                                                            //
//  You should have received a copy of the GNU General Public License         //
//  along with OS/K.  If not, see <https://www.gnu.org/licenses/>.            //
//----------------------------------------------------------------------------//

#include <libbuf.h>
#include <init/boot.h>
#include <ke/idt.h>
#include <ke/syscall.h>
#include <io/vga.h>
#include <sh/shell.h>

static error_t (*syscallTable[255])(void*, void*, void*, void*, ISRFrame_t*) = {NULL};


//
//  Syscall handler that dispatches calls depending of code value
//
error_t _KeSyscallHandler(void *rdi, void *rsi, void *rdx, void *rcx, ISRFrame_t *regs)
{    
    if ((ulong)regs->cs >= (ulong)BtLoaderInfo.codeSegment) {
        DebugLog("System call code %ld from userspace (cs %#x)\n", 
                                                                regs->rax, regs->cs);
    } else {
        DebugLog("System call call code %ld from kernel (cs %#x)\n", 
                                                                regs->rax, regs->cs);
    }
    
    if (regs->rax > LATEST_SYSCALL_CODE) {
        return ENOSYS;
    }
    
    return syscallTable[(uchar)regs->rax](rdi, rsi, rdx, rcx, regs);
}

//
//  Syscalls
//
static error_t syscallStub(void *rdi, void *rsi, void *rdx, void *rcx, ISRFrame_t *regs)
{
    return ENOSYS;
}

static error_t syscallPrint(void *id, void *string, void *rdx, void *rcx, ISRFrame_t *regs)
{
    Buffer_t *buf = NULL;
    if (*(ulong*)id == 0) {
        buf = BStdOut;
    }
    
    return BPrintOnBuf(buf, (char*)string);
}

static error_t syscallFlush(void *id, void *rdi, void *rdx, void *rcx, ISRFrame_t *regs)
{
    Buffer_t *buf = NULL;
    if (*(ulong*)id == 0) {
        buf = BStdOut;
    }
    
    return BFlushBuf(buf);
}

static error_t syscallKernelShell(void *rdi, void *rsi, void *rdx, void *rcx, ISRFrame_t *regs)
{
    KeEnableIRQs();
    ShStartShell(); //TODO : return from Shell
    KePauseIRQs();
    return EOK;
}

//
//  Initializes the syscall table
//
void KeEnableSyscalls()
{
    syscallTable[0] = syscallPrint;
    syscallTable[1] = syscallFlush;
    syscallTable[2] = syscallStub;
    syscallTable[3] = syscallStub;
    syscallTable[4] = syscallKernelShell;
    syscallTable[5] = syscallStub;
}