/**
* @file bsp_irq_asm.S
*
* Intererrupt handler for GameBoy Advance.
*/
/*
* RTEMS GBA BSP
*
* Copyright (c) 2004 Markku Puro <markku.puro@kopteri.net>
*
* The license and distribution terms for this file may be
* found in found in the file LICENSE in this distribution or at
* http://www.rtems.com/license/LICENSE.
*
* $Id$
*/
#define __asm__
#include <asm_macros.h>
#include <gba_registers.h>
#include <arm_mode_bits.h>
/* @cond INCLUDE_ASM */
/**
* Execute interrupt handler
* function void ExecuteITHandler(void)
*
* Look at interrupt status register to determine source.
* From source, determine offset into expanded vector table
* and load handler address into r0.
* irq_vector_table is defined in linkcmds
*
*/
.align
/* .section .iwram */
PUBLIC_ARM_FUNCTION(ExecuteITHandler)
ldr r1, =GBA_REG_IE_ADDR
ldrh r1, [r1]
ldr r2, =GBA_REG_IF_ADDR
ldrh r2, [r2]
and r3, r1, r2 /* only look at interrupts which are enabled */
check_lcdv:
tst r3, #0x0001
beq check_lcdh
ldr r0, =(irq_vector_table + (4 * 0)) /* load the vector number */
ldr r3,=0x0001
b get_handler
check_lcdh:
tst r3, #0x0002
beq check_lcdvc
ldr r0, =(irq_vector_table + (4 * 1)) /* load the vector number */
ldr r3,=0x0002
b get_handler
check_lcdvc:
tst r3, #0x0004
beq check_t0
ldr r0, =(irq_vector_table + (4 * 2)) /* load the vector number */
ldr r3,=0x0004
b get_handler
check_t0:
tst r3, #0x0008
beq check_t1
ldr r0, =(irq_vector_table + (4 * 3)) /* load the vector number */
ldr r3,=0x0008
b get_handler
check_t1:
tst r3, #0x0010
beq check_t2
ldr r0, =(irq_vector_table + (4 * 4)) /* load the vector number */
ldr r3,=0x0010
b get_handler
check_t2:
tst r3, #0x0020
beq check_t3
ldr r0, =(irq_vector_table + (4 * 5)) /* load the vector number */
ldr r3,=0x0020
b get_handler
check_t3:
tst r3, #0x0040
beq check_ser
ldr r0, =(irq_vector_table + (4 * 6)) /* load the vector number */
ldr r3,=0x0040
b get_handler
check_ser:
tst r3, #0x0080
beq check_dma0
ldr r0, =(irq_vector_table + (4 * 7)) /* load the vector number */
ldr r3,=0x0080
b get_handler
check_dma0:
tst r3, #0x0100
beq check_dma1
ldr r0, =(irq_vector_table + (4 * 8)) /* load the vector number */
ldr r3,=0x0100
b get_handler
check_dma1:
tst r3, #0x0200
beq check_dma2
ldr r0, =(irq_vector_table + (4 * 9)) /* load the vector number */
ldr r3,=0x0200
b get_handler
check_dma2:
tst r3, #0x0400
beq check_dma3
ldr r0, =(irq_vector_table + (4 * 10)) /* load the vector number */
ldr r3,=0x0400
b get_handler
check_dma3:
tst r3, #0x0800
beq check_keypad
ldr r0, =(irq_vector_table + (4 * 11)) /* load the vector number */
ldr r3,=0x0800
b get_handler
check_keypad:
tst r3, #0x1000
beq check_gamepak
ldr r0, =(irq_vector_table + (4 * 12)) /* load the vector number */
ldr r3,=0x1000
b get_handler
check_gamepak:
tst r3, #0x2000
beq IRQ_NoInterrupt
ldr r0, =(irq_vector_table + (4 * 13)) /* load the vector number */
ldr r3,=0x2000
b get_handler
unknown_irq:
ldr r0, =(default_int_handler) /* Unknown Interrupt? */
ldr r3,=0x0000
get_handler:
ldr r0, [r0] /* extract the IT handler */
ldr r2, =GBA_REG_IF_ADDR /* Clear IF */
strh r3, [r2]
/*
* re-enable interrupts at processor level
*/
mrs r1, cpsr
bic r1, r1, #Int_Bits
msr cpsr, r1
stmdb sp!,{lr}
ldr lr, =IRQ_return /* prepare the return from handler */
mov pc, r0 /* EXECUTE INT HANDLER */
IRQ_return:
ldmia sp!,{lr}
/*
* disable interrupts_again
*/
mrs r0, cpsr
orr r0, r0, #Int_Bits
msr cpsr, r0
IRQ_NoInterrupt:
/* return to the "main" interrupt handler */
mov pc, lr
LABEL_END(ExecuteITHandler)
/* @endcond */
