/*
 * File      : lwp_gcc.c
 * This file is part of RT-Thread RTOS
 * COPYRIGHT (C) 2006 - 2018, RT-Thread Development Team
 *
 *  This program 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 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program 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 this program; if not, write to the Free Software Foundation, Inc.,
 *  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Change Logs:
 * Date           Author       Notes
 */

#define  Mode_USR       0x10
#define  Mode_FIQ       0x11
#define  Mode_IRQ       0x12
#define  Mode_SVC       0x13
#define  Mode_MON       0x16
#define  Mode_ABT       0x17
#define  Mode_UDF       0x1B
#define  Mode_SYS       0x1F

#define A_Bit        0x100 
#define I_Bit        0x80 @; when I bit is set, IRQ is disabled
#define F_Bit        0x40 @; when F bit is set, FIQ is disabled
#define T_Bit        0x20

.cpu arm9
.syntax unified
.text

/*
 * void lwp_user_entry(args, text, data);
 */
.global lwp_user_entry
.type lwp_user_entry, % function
lwp_user_entry:
    mrs     r9, cpsr
    mov     r8, r9
    bic     r9, #0x1f
    orr     r9, #Mode_USR

    orr     r8, #I_Bit
    msr     cpsr_c, r8

    msr     spsr, r9

    /* set data address. */
    mov     r9, r2
    movs    pc, r1

/*
 * void SVC_Handler(void);
 */
.global SVC_Handler
.type SVC_Handler, % function
SVC_Handler:
    push {lr}
    mrs lr, spsr
    push {r4, r5, lr}

    mrs r4, cpsr
    bic r4, #I_Bit
    msr cpsr_c, r4

    push {r0 - r3, r12}
    and r0, r7, #0xff
    bl lwp_get_sys_api
    cmp r0, #0           /* r0 = api */
    mov r4, r0
    pop {r0 - r3, r12}
    beq svc_exit
    ldr lr, = svc_exit
    bx  r4

svc_exit:
    mrs r4, cpsr
    orr r4, #I_Bit
    msr cpsr_c, r4

    pop {r4, r5, lr}
    msr spsr_cxsf, lr
    pop {lr}
    movs pc, lr