/*
	TinyLoad - a simple region free (original) game launcher in 4k

# This code is licensed to you under the terms of the GNU GPL, version 2;
# see file COPYING or http://www.gnu.org/licenses/old-licenses/gpl-2.0.txt

# This code comes from the Twilight Hack
# Copyright 2008-2009  Segher Boessenkool  <segher@kernel.crashing.org>

# Slightly modified to imitate the homebrew channel stub

*/
.set r0,0;		.set r1,1;		.set r2,2;		.set r3,3;		.set r4,4;
.set r5,5;		.set r6,6;		.set r7,7;		.set r8,8;		.set r9,9;
.set r10,10;	.set r11,11;	.set r12,12;	.set r13,13;	.set r14,14;
.set r15,15;	.set r16,16;	.set r17,17;	.set r18,18;	.set r19,19;
.set r20,20;	.set r21,21;	.set r22,22;	.set r23,23;	.set r24,24;
.set r25,25;	.set r26,26;	.set r27,27;	.set r28,28;	.set r29,29;
.set r30,30;	.set r31,31;

#include "hw.h"

.extern _main
#TODO - fixup memset
	.globl _start
_start:
	bl      __init_registers
	bl      __init_memory
	bl      __init_syscall
	bl      __init_sprs
	lis     r3,__bss_start@h
	ori     r3,r3,__bss_start@l
	li      r4,0
	lis     r5,__bss_end@h
	ori     r5,r5,__bss_end@l
	subf    r5,r3,r5
	bl      _memset
	lis		r3,__stack_end@h
	ori		r3,r3,__stack_end@l
	li		r4,0
	lis		r5,__stack_top@h
	ori		r5,r5,__stack_top@l
	subf	r5,r3,r5
	bl		_memset
	bl      _main
0:
	b       0b

__init_registers:
	li      r0,0
	li      r3,0
	li      r4,0
	li      r5,0
	li      r6,0
	li      r7,0
	li      r8,0
	li      r9,0
	li      r10,0
	li      r11,0
	li      r12,0
	li      r14,0
	li      r15,0
	li      r16,0
	li      r17,0
	li      r18,0
	li      r19,0
	li      r20,0
	li      r21,0
	li      r22,0
	li      r23,0
	li      r24,0
	li      r25,0
	li      r26,0
	li      r27,0
	li      r28,0
	li      r29,0
	li      r30,0
	li      r31,0
	lis     r1,__stack_top@h
	ori     r1,r1,__stack_top@l
	addi    r1,r1,-4
	stw     r0,0(r1)
	stwu    r1,-0x38(r1)
	lis     r2,0
	ori     r2,r2,0x8000
	lis     r13,0
	ori     r13,r13,0x8000
	blr

_memset:
	clrlwi. r6,r5,29
	rlwinm  r5,r5,30,2,31
	addi    r3,r3,-4
	mtctr   r5
0:
	stwu    r4,4(r3)
	bdnz+   0b
	cmplwi  r6,0
	beq-    2f
1:
	stbu    r4,1(r3)
	addic.  r6,r6,-1
	bne+    1b
2:
	blr

__init_memory:
	mflr    r0
	stw     r0, 0x04(r1)
	stwu    r1,-0x10(r1)
	stw     r31,0x0C(r1)
	mfspr   r3,rHID0
	rlwinm  r0,r3,0,16,16		#HID0[ICE]
	cmplwi  r0,0
	bne-    0f
	bl      ICacheEnable
0:
	mfspr   r3,rHID0
	rlwinm  r0,r3,0,17,17		#HID0[DCE]
	cmplwi  r0,0
	bne-    1f
	bl      DCacheEnable
1:
	mfl2cr  r3
	rlwinm  r0,r3,0,0,0			#L2CR[L2E]
	cmplwi  r0,0
	bne-    2f
	bl      L2_Init
	bl      L2_Enable
2:
	lwz     r0, 0x14(r1)
	lwz     r31,0x0C(r1)
	addi    r1,r1,0x10
	mtlr    r0
	blr

__init_sprs:
	mflr    r0
	stw     r0, 0x04(r1)
	stwu    r1,-0x18(r1)
	stw     r31,0x14(r1)
	stw     r30,0x10(r1)
	stw     r29,0x0C(r1)
	li      r3,0
	mtmmcr0 r3
	mtmmcr1 r3
	mtpmc1  r3
	mtpmc2  r3
	mtpmc3  r3
	mtpmc4  r3
	mfspr   r3,rHID0
	ori     r3,r3,HID0_SPD	#HID0[SPD]
	mtspr   rHID0,r3
	mfspr   r3,rHID2
	rlwinm  r3,r3,0,2,0		#HID2[WPE]
	mtspr   rHID2,r3
	lwz     r0, 0x1C(r1)
	lwz     r31,0x14(r1)
	lwz     r30,0x10(r1)
	lwz     r29,0x0C(r1)
	addi    r1,r1,0x18
	mtlr    r0
	blr