melonDS/freebios/bios_common.S

#  Custom NDS ARM7/ARM9 BIOS replacement
#  Copyright (c) 2013, Gilead Kutnick
#  All rights reserved.
#  
#  Redistribution and use in source and binary forms, with or without
#   modification, are permitted provided that the following conditions are met:
#  
#  1) Redistributions of source code must retain the above copyright notice,
#     this list of conditions and the following disclaimer.
#  2) 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.
#  
#  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "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 COPYRIGHT HOLDER OR CONTRIBUTORS 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.

.section .text

.org 0x00000000

// Vector table

b boot_handler                        // 0x00 Reset
b unhandled_exception                 // 0x04 Undefined
b swi_handler                         // 0x08 SWI
b unhandled_exception                 // 0x0C Abort Prefetch
b unhandled_exception                 // 0x10 Abort Data
b unhandled_exception                 // 0x14 Reserved
b interrupt_handler                   // 0x18 IRQ
b unhandled_exception                 // 0x1C FIQ

#ifdef BIOS_ARM9
// ARM9 BIOS has a logo here (0x9C bytes), we don't want to include the logo
// but we'll leave a space for it.

.fill 0xe0, 0x1, 0x0
#endif

#ifdef BIOS_ARM7
// ARM7 BIOS has encryption stuff at 0x30, we don't want to include it but we'll
// leave a space for it.

.fill 0x1058, 0x1, 0x0
#endif


// TODO: This needs to be implemented. Not needed for emulators that HLE bootup.
boot_handler:
 0:
  b 0b

// Not sure what this should do, it's probably best to be pretty visible though.
unhandled_exception:
 0:
  b 0b


#ifdef BIOS_ARM7
  #define swi_label(function) .word function
  #define swi_label_arm7_only(function) swi_label(function)
#else
  #define swi_label_arm7_only(function) swi_label(swi_invalid)
#endif

#ifdef BIOS_ARM9
  #define swi_label(function) .word (function + 0xFFFF0000)
  #define swi_label_arm9_only(function) swi_label(function)
#else
  #define swi_label_arm9_only(function) swi_label(swi_invalid)
#endif

// SWI calling convention:
// Parameters are passed in via r0 - r3
// Called SWI can modify r0 - r3 (and return things here) and r4, r12, and r14.
// They can't modify anything else.

#define swi_comment     r12
#define saved_spsr      r4
#define modified_spsr   r4

swi_handler:
  // Save these as temporaries
  stmdb sp!, { r4, r12, lr }

  // get SPSR and enter system mode, interrupts on
  mrs saved_spsr, SPSR
  // This must be stacked and not just saved, because otherwise SWI won't
  // be reentrant, which can happen if you're waiting for interrupts and the
  // interrupt handler triggers the SWI.
  stmdb sp!, { saved_spsr }
  and modified_spsr, saved_spsr, #0x80
  orr modified_spsr, modified_spsr, #0x1F

  // Load comment from SWI instruction, which indicates which SWI
  // to use.
  ldrb swi_comment, [ lr, #-2 ]
  msr CPSR_fc, modified_spsr

  // We have to now save system-mode lr register as well
  stmdb sp!, { lr }

  // Not sure if this should be here or not, but it probably doesn't
  // hurt, and is better than flooding the table with 256 entries..
  // This will move in the known entry of an invalid SWI.
  cmp swi_comment, #0x20
  movge swi_comment, #0x01

  // Branch to SWI handler
  ldr pc, [ pc, swi_comment, lsl #2 ]
  nop

  // SWI table begins here
  // If there's no entry just go straight to swi_complete
  swi_label(swi_soft_reset)                                  // 00
  swi_label(swi_invalid)                                     // 01
  swi_label(swi_invalid)                                     // 02
  swi_label(swi_wait_by_loop)                                // 03
  swi_label(swi_interrupt_wait)                              // 04
  swi_label(swi_vblank_interrupt_wait)                       // 05
  swi_label(swi_halt)                                        // 06
  swi_label_arm7_only(swi_stop)                              // 07
  swi_label_arm7_only(swi_sound_bias)                        // 08
  swi_label(swi_divide)                                      // 09
  swi_label(swi_invalid)                                     // 0A
  swi_label(swi_cpu_set)                                     // 0B
  swi_label(swi_cpu_fast_set)                                // 0C
  swi_label(swi_sqrt)                                        // 0D
  swi_label(swi_get_crc16)                                   // 0E
  swi_label(swi_is_debugger)                                 // 0F
  swi_label(swi_bit_unpack)                                  // 10
  swi_label(swi_lz77_decompress_wram)                        // 11
  swi_label(swi_lz77_decompress_vram)                        // 12
  swi_label(swi_huffman_decompress)                          // 13
  swi_label(swi_runlength_decompress_wram)                   // 14
  swi_label(swi_runlength_decompress_vram)                   // 15
  swi_label_arm9_only(swi_diff_8bit_unfilter_wram)           // 16
  swi_label(swi_invalid)                                     // 17
  swi_label_arm9_only(swi_diff_16bit_unfilter)               // 18
  swi_label(swi_invalid)                                     // 19
  swi_label_arm7_only(swi_get_sine_table)                    // 1A
  swi_label_arm7_only(swi_get_pitch_table)                   // 1B
  swi_label_arm7_only(swi_get_volume_table)                  // 1C
  swi_label_arm7_only(swi_get_boot_procs)                    // 1D
  swi_label(swi_custom_halt_post)                            // 1F

swi_invalid:
  // This just passes through to completion.

// SWI returns here
swi_complete:
  // Restore system mode lr
  ldmia sp!, { lr }

  // Go back to supervisor mode to get back to that stack
  mov modified_spsr, #0xD3
  msr CPSR_fc, modified_spsr

  // SPSR has to be restored because the transition to system mode broke it
  ldmia sp!, { saved_spsr }
  msr SPSR, saved_spsr

  // Restore stuff we saved
  ldmia sp!, { r4, r12, lr }

  // Return from exception handler
  movs pc, lr  


padding_a:
  .word 0x0

swi_halt:
#ifdef BIOS_ARM7
  mov r0, #0x04000000
  mov r2, #0x80
  strb r2, [ r0, #0x301 ]
#else
  mov r0, #0x0
  mcr p15, 0, r0, cr7, cr0, 4
#endif
  b swi_complete

swi_wait_by_loop:
 0:
  subs r0, r0, #1
  bgt 0b

  b swi_complete

#define check_immediately r0
#define irq_wait_mask     r1

#ifdef BIOS_ARM7
  #define irq_flag_base   r3
#else
  #define irq_flag_base   r2
#endif

#define io_base           r3
#define const_0x1         r12

#define irq_flags         r0

interrupt_check:
#ifdef BIOS_ARM9
  // Get DTCM base
  mrc p15, 0, irq_flag_base, cr9, cr1, 0
  bic irq_flag_base, irq_flag_base, #0xFF

  // Software IRQ flag is at DTCM[0x3FF8]
  add irq_flag_base, irq_flag_base, #0x4000
#endif

  // Load software IRQ flag
  ldr irq_flags, [ irq_flag_base, #-8 ]

  // Set IME (0x04000208) to 0
  str io_base, [ io_base, #0x208 ]

  // Check if IRQs were risen, to see if the loop can exit
  tst irq_wait_mask, irq_flags

  // Clear IRQs that were risen and write back
  bic irq_flags, irq_flags, irq_wait_mask
  str irq_flags, [ irq_flag_base, #-8 ]

  mov const_0x1, #0x1
  // Set IME (0x04000208) to 1 and return
  str const_0x1, [ io_base, #0x208 ]
  bx lr


#define halt_value        r0

swi_vblank_interrupt_wait:
  // Check immediately for VBLANK interrupt
  mov check_immediately, #1
  mov irq_wait_mask, #1

  // Fall through

swi_interrupt_wait:
  mov io_base, #0x4000000

  // See if we should return immediately or halt
  cmp check_immediately, #0
  blne interrupt_check
  
  // Perform this loop until the interrupt is risen
 0:
#ifdef BIOS_ARM9
  // Halt ARM9 via coprocessor instruction
  mov halt_value, #0
  mcr p15, 0, halt_value, cr7, cr0, 4
#else
  mov halt_value, #0x80
  // Set HALTCNT to 0x80
  strb halt_value, [ io_base, #0x301 ]
#endif

  bl interrupt_check
  beq 0b

  b swi_complete

swi_interrupt_check_first:
  // Check for IRQ
  bl interrupt_check
  // If set exit.
  bne swi_complete

  // If not wait for interrupt.
  b 0b


#ifdef BIOS_ARM7

swi_stop:
  mov r0, #0x04000000
  mov r1, #0xC0
  strb r1, [ r0, #0x301 ]
  b swi_complete

#define bias_ptr        r0
#define bias_value      r1

swi_sound_bias:
  mov bias_ptr, #0x4000000
  add bias_ptr, bias_ptr, #0x500
  ldr bias_value, [ bias_ptr, #0x4 ]
  cmp bias_value, #0
  movne bias_value, #0x200
  str bias_value, [ bias_ptr, #0x4 ]

  // TODO: Needs to add delay
  b swi_complete
  
#endif


#define numerator           r0
#define denominator         r1
#define accumulator         r2
#define current_bit         r3

#define numerator_signed    r12
#define denominator_signed  r3

#define sign_flip           r12

#define result              r0
#define remainder           r1
#define result_abs          r3

swi_divide:
  // Set if numerator is signed, and abs numerator
  ands numerator_signed, numerator, #0x80000000
  rsbmi numerator, numerator, #0

  // Same with denominator
  ands denominator_signed, denominator, #0x80000000
  rsbmi denominator, denominator, #0

  // Gets set if sign(numerator) != sign(denominator)
  eor sign_flip, numerator_signed, denominator_signed

  mov accumulator, #0
  mov current_bit, #1

  // This moves out the current bit to the MSB of the denominator,
  // and aligns the denominator up to the same bit-length as the
  // numerator
 0:
  cmp denominator, numerator
  movls denominator, denominator, lsl #1
  movls current_bit, current_bit, lsl #1
  bls 0b

  // Basically the grade-school algorithm, for unsigned integers in binary
 1:
  cmp numerator, denominator
  subcs numerator, numerator, denominator
  orrcs accumulator, accumulator, current_bit
  movs current_bit, current_bit, lsr #1
  movcc denominator, denominator, lsr #1
  bcc 1b

  mov remainder, numerator
  mov result_abs, accumulator
  mov result, accumulator

  tst sign_flip, #0x80000000
  rsbmi result, result, #0

  b swi_complete


#define source        r0
#define dest          r1
#define copy_control  r2
#define value         r3

#define length        r12

swi_cpu_set:
  // Only take 21 bits for length.
  bic length, copy_control, #0xFF000000
  bic length, length, #0x00E00000

  tst copy_control, #(1 << 26)
  bne copy_32bit

 copy_16bit:
  tst copy_control, #(1 << 24)
  bic source, #0x1
  bic dest, #0x1
  bne set_16bit

 0:
  ldrh value, [ source ], #2
  subs length, length, #1
  strh value, [ dest ], #2
  bne 0b

  b swi_complete

 set_16bit:
  ldrh value, [ source ]

 0:
  strh value, [ dest ], #2
  subs length, length, #1
  bne 0b

  b swi_complete

 copy_32bit:
  tst copy_control, #(1 << 24)
  bic source, #0x3
  bic dest, #0x3
  bne set_32bit

 0:
  ldr value, [ source ], #4
  subs length, length, #1
  str value, [ dest ], #4
  bne 0b

  b swi_complete

 set_32bit:
  ldr value, [ source ]

 0:
  str value, [ dest ], #4
  subs length, length, #1
  bne 0b

  b swi_complete


// TODO: Make this actually faster (ldm/stm)
swi_cpu_fast_set:
  // Only take 21 bits for length.
  bic length, copy_control, #0xFF000000
  bic length, length, #0x00E00000

  tst copy_control, #(1 << 24)
  bic source, #0x3
  bic dest, #0x3
  bne fast_set_32bit

 0:
  ldr value, [ source ], #4
  subs length, length, #1
  str value, [ dest ], #4
  bne 0b

  b swi_complete

 fast_set_32bit:
  ldr value, [ source ]

 0:
  str value, [ dest ], #4
  subs length, length, #1
  bne 0b

  b swi_complete


#undef remainder

#define sqrt_value      r0
#define remainder       r0
#define result          r0

#define square_index    r1
#define root            r2
#define root_check      r3

swi_sqrt:
  mov square_index, #0x40000000
  mov root, #0x0

 0:
  orr root_check, square_index, root
  cmp remainder, root_check
  subge remainder, remainder, root_check
  mov root, root, lsr #1
  orrge root, root, square_index
  movs square_index, square_index, lsr #2
  bne 0b

  mov result, root
  b swi_complete

 
#undef current_value

#define crc_value       r0
#define crc_ptr         r1
#define crc_length      r2

#define current_value   r3
#define const_0x1E      r4
#define crc_index       r5
#define crc_table_ptr   r14

#define crc_lookup      r12

#define crc_nibble(shift)                                                     ;\
  and crc_index, const_0x1E, crc_value, lsl #1                                ;\
  ldrh crc_lookup, [ crc_table_ptr, crc_index ]                               ;\
  mov crc_value, crc_value, lsr #4                                            ;\
  eor crc_value, crc_value, crc_lookup                                        ;\
                                                                              ;\
  and crc_index, const_0x1E, current_value, shift                             ;\
  ldrh crc_lookup, [ crc_table_ptr, crc_index ]                               ;\
  eor crc_value, crc_value, crc_lookup                                        ;\

crc_table:
	.hword 0x0000, 0xCC01, 0xD801, 0x1400, 0xF001, 0x3C00, 0x2800, 0xE401
  .hword 0xA001, 0x6C00, 0x7800, 0xB401, 0x5000, 0x9C01, 0x8801, 0x4400

swi_get_crc16:
  stmdb sp!, { r5 }
  mov const_0x1E, #0x1E
  adr crc_table_ptr, crc_table

  movs crc_length, crc_length, lsr #1
  beq 1f

 0:
  ldrh current_value, [ crc_ptr ], #2

  crc_nibble(lsl #1)
  crc_nibble(lsr #3)
  crc_nibble(lsr #7)
  crc_nibble(lsr #11)

  subs crc_length, crc_length, #1
  bne 0b

 1:
  ldmia sp!, { r5 }
  b swi_complete


swi_is_debugger:
  mov r0, #0
  b swi_complete


#undef length

#define source              r0
#define dest                r1
#define unpack_data         r2
#define length              r3

#define source_bit_width    r12
#define dest_bit_width      r14
#define data_offset         r4
#define offset_zero         r2
#define source_mask         r5
#define source_bit_buffer   r6
#define dest_bit_buffer     r7
#define dest_bits_loaded    r8
#define source_value        r9

swi_bit_unpack:
  stmdb sp!, { r5 - r9 }

  ldrh length, [ unpack_data, #0 ]
  ldrb source_bit_width, [ unpack_data, #2 ]
  ldrb dest_bit_width, [ unpack_data, #3 ]
  ldr data_offset, [ unpack_data, #4 ]

  // TODO: Check that bits are <= 32 and a power of 2?
  mov offset_zero, data_offset, lsr #31
  bic data_offset, data_offset, #0x80000000

  mov source_mask, #0x1
  mov source_mask, source_mask, lsl source_bit_width
  sub source_mask, source_mask, #1

  mov source_bit_buffer, #0x1
  mov dest_bit_buffer, #0
  mov dest_bits_loaded, #0

  cmp source_bit_width, #1
  moveq length, length, lsl #3

  cmp source_bit_width, #2
  moveq length, length, lsl #2

  cmp source_bit_width, #4
  moveq length, length, lsl #1

 0:
  // Reload bit buffer if necessary
  cmp source_bit_buffer, #0x1
  ldreqb source_bit_buffer, [ source ], #1
  orreq source_bit_buffer, source_bit_buffer, #0x100

  // Get next from source
  and source_value, source_bit_buffer, source_mask
  mov source_bit_buffer, source_bit_buffer, lsr source_bit_width

  cmp source_value, #0
  tsteq offset_zero, #0x1
  addne source_value, source_value, data_offset
  
  // Put it on dest buffer
  orr dest_bit_buffer, dest_bit_buffer, source_value, lsl dest_bits_loaded
  add dest_bits_loaded, dest_bits_loaded, dest_bit_width

  // If dest buffer is full write out
  cmp dest_bits_loaded, #32
  streq dest_bit_buffer, [ dest ], #4
  moveq dest_bit_buffer, #0
  moveq dest_bits_loaded, #0

  subs length, length, #1
  bne 0b

  ldmia sp!, { r5 - r9 }
  b swi_complete


#undef length
 
#define source            r0
#define dest              r1
#define length            r2
#define header            r3

#define lz77_control      r3
#define lz77_value        r4
#define lz77_vram_tmp     r5
#define lz77_value_b      r14
#define window_length     r14
#define window_offset     r12
#define window_ptr        r12

swi_lz77_decompress_wram:
  ldr header, [ source ], #4
  movs length, header, lsr #8
  beq swi_complete

 0:
  ldrb lz77_control, [ source ], #1
  // This will hit the MSB after 8 iterations
  orr lz77_control, lz77_control, #(1 << 23)

 1:
  tst lz77_control, #0x80
  beq 2f

  // Load a window of data that was loaded before

  // Read 16-bit unaligned value
  ldrb lz77_value, [ source ], #1
  ldrb lz77_value_b, [ source ], #1
  orr lz77_value, lz77_value_b, lz77_value, lsl #8

  // Get length and offset from lz77 value
  mov window_length, lz77_value, lsr #12
  bic window_offset, lz77_value, #0xF000
  
  add window_length, window_length, #3
  sub window_ptr, dest, window_offset
  sub window_ptr, window_ptr, #1

 3:
  ldrb lz77_value, [ window_ptr ], #1
  subs length, length, #1
  strb lz77_value, [ dest ], #1
  beq swi_complete

  subs window_length, window_length, #1
  bne 3b

  movs lz77_control, lz77_control, lsl #1
  bpl 1b
  b 0b

  // Load a single value
 2:
  ldrb lz77_value, [ source ], #1
  subs length, length, #1
  strb lz77_value, [ dest ], #1
  beq swi_complete

  movs lz77_control, lz77_control, lsl #1
  bpl 1b
  b 0b
  

swi_lz77_decompress_vram:
  ldr header, [ source ], #4
  movs length, header, lsr #8
  beq swi_complete
  
  stmdb sp!, { r5 }
  mov r5, #0

 0:
  ldrb lz77_control, [ source ], #1
  // This will hit the MSB after 8 iterations
  orr lz77_control, lz77_control, #(1 << 23)

 1:
  tst lz77_control, #0x80
  beq 2f

  // Load a window of data that was loaded before

  // Read 16-bit unaligned value
  ldrb lz77_value, [ source ], #1
  ldrb lz77_value_b, [ source ], #1
  orr lz77_value, lz77_value_b, lz77_value, lsl #8

  // Get length and offset from lz77 value
  mov window_length, lz77_value, lsr #12
  bic window_offset, lz77_value, #0xF000
  
  add window_length, window_length, #3
  sub window_ptr, dest, window_offset
  sub window_ptr, window_ptr, #1

 3:
  tst dest, #1
  ldreqb lz77_vram_tmp, [ window_ptr ], #1
  ldrneb lz77_value, [ window_ptr ], #1
  orrne lz77_value, lz77_vram_tmp, lz77_value, lsl #8
  strneh lz77_value, [ dest, #-1 ]
  add dest, dest, #1
  
  subs length, length, #1
  ldmeqia sp!, { r5 }
  beq swi_complete

  subs window_length, window_length, #1
  bne 3b

  movs lz77_control, lz77_control, lsl #1
  bpl 1b
  b 0b

  // Load a single value
 2:
  tst dest, #1
  ldreqb lz77_vram_tmp, [ source ], #1
  ldrneb lz77_value, [ source ], #1
  orrne lz77_value, lz77_vram_tmp, lz77_value, lsl #8
  strneh lz77_value, [ dest, #-1 ]
  add dest, dest, #1
  
  subs length, length, #1
  ldmeqia sp!, { r5 }
  beq swi_complete

  movs lz77_control, lz77_control, lsl #1
  bpl 1b
  b 0b
 

// TODO: Needs to be implemented 
swi_huffman_decompress:
  b swi_complete

  
#define source        r0
#define dest          r1
#define length        r2
#define header        r3

#define rle_control   r3
#define run_length    r3
#define rle_value     r12
 
// TODO: Make a safe one for VRAM.
 
swi_runlength_decompress_vram:
swi_runlength_decompress_wram:
  ldr header, [ source ], #4

  mov length, header, lsr #8

 0:
  ldrb rle_control, [ source ], #1
  tst rle_control, #0x80
  and run_length, rle_control, #0x7F
  beq 1f

  ldrb rle_value, [ source ], #1
  add run_length, run_length, #3

 2:
  strb rle_value, [ dest ], #1
  subs length, length, #1
  beq swi_complete

  subs run_length, run_length, #1
  bne 2b

  b 0b

 1:
  add run_length, run_length, #1
  
 2:
  ldrb rle_value, [ source ], #1
  subs length, length, #1
  strb rle_value, [ dest ], #1

  beq swi_complete

  subs run_length, run_length, #1
  bne 2b

  b 0b
  

#ifdef BIOS_ARM9

#undef accumulator
#undef length

#define source        r0
#define dest          r1
#define length        r2
#define header        r3

#define accumulator   r12
#define current_value r3

swi_diff_8bit_unfilter_wram:
  ldr header, [ source ], #4

  ldrb accumulator, [ source ], #1
  mov length, header, lsr #8

  strb accumulator, [ dest ], #1
  sub length, length, #1

 0:
  ldrb current_value, [ source ], #1
  subs length, length, #1
  add accumulator, accumulator, current_value
  strb accumulator, [ dest ], #1
  bne 0b

  b swi_complete


swi_diff_16bit_unfilter:
  ldr header, [ source ], #4

  ldrh accumulator, [ source ], #2
  mov length, header, lsr #8

  strh accumulator, [ dest ], #2
  bic length, length, #0x1

  sub length, length, #2

 0:
  ldrh current_value, [ source ], #2
  subs length, length, #2
  add accumulator, accumulator, current_value
  strh accumulator, [ dest ], #2
  bne 0b

  b swi_complete

#endif


#ifdef BIOS_ARM7
sine_table:
  .hword 0x0000, 0x0324, 0x0648, 0x096A, 0x0C8C, 0x0FAB, 0x12C8, 0x15E2
  .hword 0x18F9, 0x1C0B, 0x1F1A, 0x2223, 0x2528, 0x2826, 0x2B1F, 0x2E11
  .hword 0x30FB, 0x33DF, 0x36BA, 0x398C, 0x3C56, 0x3F17, 0x41CE, 0x447A
  .hword 0x471C, 0x49B4, 0x4C3F, 0x4EBF, 0x5133, 0x539B, 0x55F5, 0x5842
  .hword 0x5A82, 0x5CB3, 0x5ED7, 0x60EB, 0x62F1, 0x64E8, 0x66CF, 0x68A6
  .hword 0x6A6D, 0x6C23, 0x6DC9, 0x6F5E, 0x70E2, 0x7254, 0x73B5, 0x7504
  .hword 0x7641, 0x776B, 0x7884, 0x7989, 0x7A7C, 0x7B5C, 0x7C29, 0x7CE3
  .hword 0x7D89, 0x7E1D, 0x7E9C, 0x7F09, 0x7F61, 0x7FA6, 0x7FD8, 0x7FF5

swi_get_sine_table:
  add r0, r0, r0
  adr r1, sine_table
  // Should some protection be here?
  ldrh r0, [ r1, r0 ]
  b swi_complete

pitch_table:
  .hword 0x0000, 0x003B, 0x0076, 0x00B2, 0x00ED, 0x0128, 0x0164, 0x019F
  .hword 0x01DB, 0x0217, 0x0252, 0x028E, 0x02CA, 0x0305, 0x0341, 0x037D
  .hword 0x03B9, 0x03F5, 0x0431, 0x046E, 0x04AA, 0x04E6, 0x0522, 0x055F
  .hword 0x059B, 0x05D8, 0x0614, 0x0651, 0x068D, 0x06CA, 0x0707, 0x0743
  .hword 0x0780, 0x07BD, 0x07FA, 0x0837, 0x0874, 0x08B1, 0x08EF, 0x092C
  .hword 0x0969, 0x09A7, 0x09E4, 0x0A21, 0x0A5F, 0x0A9C, 0x0ADA, 0x0B18
  .hword 0x0B56, 0x0B93, 0x0BD1, 0x0C0F, 0x0C4D, 0x0C8B, 0x0CC9, 0x0D07
  .hword 0x0D45, 0x0D84, 0x0DC2, 0x0E00, 0x0E3F, 0x0E7D, 0x0EBC, 0x0EFA
  .hword 0x0F39, 0x0F78, 0x0FB6, 0x0FF5, 0x1034, 0x1073, 0x10B2, 0x10F1
  .hword 0x1130, 0x116F, 0x11AE, 0x11EE, 0x122D, 0x126C, 0x12AC, 0x12EB
  .hword 0x132B, 0x136B, 0x13AA, 0x13EA, 0x142A, 0x146A, 0x14A9, 0x14E9
  .hword 0x1529, 0x1569, 0x15AA, 0x15EA, 0x162A, 0x166A, 0x16AB, 0x16EB
  .hword 0x172C, 0x176C, 0x17AD, 0x17ED, 0x182E, 0x186F, 0x18B0, 0x18F0
  .hword 0x1931, 0x1972, 0x19B3, 0x19F5, 0x1A36, 0x1A77, 0x1AB8, 0x1AFA
  .hword 0x1B3B, 0x1B7D, 0x1BBE, 0x1C00, 0x1C41, 0x1C83, 0x1CC5, 0x1D07
  .hword 0x1D48, 0x1D8A, 0x1DCC, 0x1E0E, 0x1E51, 0x1E93, 0x1ED5, 0x1F17
  .hword 0x1F5A, 0x1F9C, 0x1FDF, 0x2021, 0x2064, 0x20A6, 0x20E9, 0x212C
  .hword 0x216F, 0x21B2, 0x21F5, 0x2238, 0x227B, 0x22BE, 0x2301, 0x2344
  .hword 0x2388, 0x23CB, 0x240E, 0x2452, 0x2496, 0x24D9, 0x251D, 0x2561
  .hword 0x25A4, 0x25E8, 0x262C, 0x2670, 0x26B4, 0x26F8, 0x273D, 0x2781
  .hword 0x27C5, 0x280A, 0x284E, 0x2892, 0x28D7, 0x291C, 0x2960, 0x29A5
  .hword 0x29EA, 0x2A2F, 0x2A74, 0x2AB9, 0x2AFE, 0x2B43, 0x2B88, 0x2BCD
  .hword 0x2C13, 0x2C58, 0x2C9D, 0x2CE3, 0x2D28, 0x2D6E, 0x2DB4, 0x2DF9
  .hword 0x2E3F, 0x2E85, 0x2ECB, 0x2F11, 0x2F57, 0x2F9D, 0x2FE3, 0x302A
  .hword 0x3070, 0x30B6, 0x30FD, 0x3143, 0x318A, 0x31D0, 0x3217, 0x325E
  .hword 0x32A5, 0x32EC, 0x3332, 0x3379, 0x33C1, 0x3408, 0x344F, 0x3496
  .hword 0x34DD, 0x3525, 0x356C, 0x35B4, 0x35FB, 0x3643, 0x368B, 0x36D3
  .hword 0x371A, 0x3762, 0x37AA, 0x37F2, 0x383A, 0x3883, 0x38CB, 0x3913
  .hword 0x395C, 0x39A4, 0x39ED, 0x3A35, 0x3A7E, 0x3AC6, 0x3B0F, 0x3B58
  .hword 0x3BA1, 0x3BEA, 0x3C33, 0x3C7C, 0x3CC5, 0x3D0E, 0x3D58, 0x3DA1
  .hword 0x3DEA, 0x3E34, 0x3E7D, 0x3EC7, 0x3F11, 0x3F5A, 0x3FA4, 0x3FEE
  .hword 0x4038, 0x4082, 0x40CC, 0x4116, 0x4161, 0x41AB, 0x41F5, 0x4240
  .hword 0x428A, 0x42D5, 0x431F, 0x436A, 0x43B5, 0x4400, 0x444B, 0x4495
  .hword 0x44E1, 0x452C, 0x4577, 0x45C2, 0x460D, 0x4659, 0x46A4, 0x46F0
  .hword 0x473B, 0x4787, 0x47D3, 0x481E, 0x486A, 0x48B6, 0x4902, 0x494E
  .hword 0x499A, 0x49E6, 0x4A33, 0x4A7F, 0x4ACB, 0x4B18, 0x4B64, 0x4BB1
  .hword 0x4BFE, 0x4C4A, 0x4C97, 0x4CE4, 0x4D31, 0x4D7E, 0x4DCB, 0x4E18
  .hword 0x4E66, 0x4EB3, 0x4F00, 0x4F4E, 0x4F9B, 0x4FE9, 0x5036, 0x5084
  .hword 0x50D2, 0x5120, 0x516E, 0x51BC, 0x520A, 0x5258, 0x52A6, 0x52F4
  .hword 0x5343, 0x5391, 0x53E0, 0x542E, 0x547D, 0x54CC, 0x551A, 0x5569
  .hword 0x55B8, 0x5607, 0x5656, 0x56A5, 0x56F4, 0x5744, 0x5793, 0x57E2
  .hword 0x5832, 0x5882, 0x58D1, 0x5921, 0x5971, 0x59C1, 0x5A10, 0x5A60
  .hword 0x5AB0, 0x5B01, 0x5B51, 0x5BA1, 0x5BF1, 0x5C42, 0x5C92, 0x5CE3
  .hword 0x5D34, 0x5D84, 0x5DD5, 0x5E26, 0x5E77, 0x5EC8, 0x5F19, 0x5F6A
  .hword 0x5FBB, 0x600D, 0x605E, 0x60B0, 0x6101, 0x6153, 0x61A4, 0x61F6
  .hword 0x6248, 0x629A, 0x62EC, 0x633E, 0x6390, 0x63E2, 0x6434, 0x6487
  .hword 0x64D9, 0x652C, 0x657E, 0x65D1, 0x6624, 0x6676, 0x66C9, 0x671C
  .hword 0x676F, 0x67C2, 0x6815, 0x6869, 0x68BC, 0x690F, 0x6963, 0x69B6
  .hword 0x6A0A, 0x6A5E, 0x6AB1, 0x6B05, 0x6B59, 0x6BAD, 0x6C01, 0x6C55
  .hword 0x6CAA, 0x6CFE, 0x6D52, 0x6DA7, 0x6DFB, 0x6E50, 0x6EA4, 0x6EF9
  .hword 0x6F4E, 0x6FA3, 0x6FF8, 0x704D, 0x70A2, 0x70F7, 0x714D, 0x71A2
  .hword 0x71F7, 0x724D, 0x72A2, 0x72F8, 0x734E, 0x73A4, 0x73FA, 0x7450
  .hword 0x74A6, 0x74FC, 0x7552, 0x75A8, 0x75FF, 0x7655, 0x76AC, 0x7702
  .hword 0x7759, 0x77B0, 0x7807, 0x785E, 0x78B4, 0x790C, 0x7963, 0x79BA
  .hword 0x7A11, 0x7A69, 0x7AC0, 0x7B18, 0x7B6F, 0x7BC7, 0x7C1F, 0x7C77
  .hword 0x7CCF, 0x7D27, 0x7D7F, 0x7DD7, 0x7E2F, 0x7E88, 0x7EE0, 0x7F38
  .hword 0x7F91, 0x7FEA, 0x8042, 0x809B, 0x80F4, 0x814D, 0x81A6, 0x81FF
  .hword 0x8259, 0x82B2, 0x830B, 0x8365, 0x83BE, 0x8418, 0x8472, 0x84CB
  .hword 0x8525, 0x857F, 0x85D9, 0x8633, 0x868E, 0x86E8, 0x8742, 0x879D
  .hword 0x87F7, 0x8852, 0x88AC, 0x8907, 0x8962, 0x89BD, 0x8A18, 0x8A73
  .hword 0x8ACE, 0x8B2A, 0x8B85, 0x8BE0, 0x8C3C, 0x8C97, 0x8CF3, 0x8D4F
  .hword 0x8DAB, 0x8E07, 0x8E63, 0x8EBF, 0x8F1B, 0x8F77, 0x8FD4, 0x9030
  .hword 0x908C, 0x90E9, 0x9146, 0x91A2, 0x91FF, 0x925C, 0x92B9, 0x9316
  .hword 0x9373, 0x93D1, 0x942E, 0x948C, 0x94E9, 0x9547, 0x95A4, 0x9602
  .hword 0x9660, 0x96BE, 0x971C, 0x977A, 0x97D8, 0x9836, 0x9895, 0x98F3
  .hword 0x9952, 0x99B0, 0x9A0F, 0x9A6E, 0x9ACD, 0x9B2C, 0x9B8B, 0x9BEA
  .hword 0x9C49, 0x9CA8, 0x9D08, 0x9D67, 0x9DC7, 0x9E26, 0x9E86, 0x9EE6
  .hword 0x9F46, 0x9FA6, 0xA006, 0xA066, 0xA0C6, 0xA127, 0xA187, 0xA1E8
  .hword 0xA248, 0xA2A9, 0xA30A, 0xA36B, 0xA3CC, 0xA42D, 0xA48E, 0xA4EF
  .hword 0xA550, 0xA5B2, 0xA613, 0xA675, 0xA6D6, 0xA738, 0xA79A, 0xA7FC
  .hword 0xA85E, 0xA8C0, 0xA922, 0xA984, 0xA9E7, 0xAA49, 0xAAAC, 0xAB0E
  .hword 0xAB71, 0xABD4, 0xAC37, 0xAC9A, 0xACFD, 0xAD60, 0xADC3, 0xAE27
  .hword 0xAE8A, 0xAEED, 0xAF51, 0xAFB5, 0xB019, 0xB07C, 0xB0E0, 0xB145
  .hword 0xB1A9, 0xB20D, 0xB271, 0xB2D6, 0xB33A, 0xB39F, 0xB403, 0xB468
  .hword 0xB4CD, 0xB532, 0xB597, 0xB5FC, 0xB662, 0xB6C7, 0xB72C, 0xB792
  .hword 0xB7F7, 0xB85D, 0xB8C3, 0xB929, 0xB98F, 0xB9F5, 0xBA5B, 0xBAC1
  .hword 0xBB28, 0xBB8E, 0xBBF5, 0xBC5B, 0xBCC2, 0xBD29, 0xBD90, 0xBDF7
  .hword 0xBE5E, 0xBEC5, 0xBF2C, 0xBF94, 0xBFFB, 0xC063, 0xC0CA, 0xC132
  .hword 0xC19A, 0xC202, 0xC26A, 0xC2D2, 0xC33A, 0xC3A2, 0xC40B, 0xC473
  .hword 0xC4DC, 0xC544, 0xC5AD, 0xC616, 0xC67F, 0xC6E8, 0xC751, 0xC7BB
  .hword 0xC824, 0xC88D, 0xC8F7, 0xC960, 0xC9CA, 0xCA34, 0xCA9E, 0xCB08
  .hword 0xCB72, 0xCBDC, 0xCC47, 0xCCB1, 0xCD1B, 0xCD86, 0xCDF1, 0xCE5B
  .hword 0xCEC6, 0xCF31, 0xCF9C, 0xD008, 0xD073, 0xD0DE, 0xD14A, 0xD1B5
  .hword 0xD221, 0xD28D, 0xD2F8, 0xD364, 0xD3D0, 0xD43D, 0xD4A9, 0xD515
  .hword 0xD582, 0xD5EE, 0xD65B, 0xD6C7, 0xD734, 0xD7A1, 0xD80E, 0xD87B
  .hword 0xD8E9, 0xD956, 0xD9C3, 0xDA31, 0xDA9E, 0xDB0C, 0xDB7A, 0xDBE8
  .hword 0xDC56, 0xDCC4, 0xDD32, 0xDDA0, 0xDE0F, 0xDE7D, 0xDEEC, 0xDF5B
  .hword 0xDFC9, 0xE038, 0xE0A7, 0xE116, 0xE186, 0xE1F5, 0xE264, 0xE2D4
  .hword 0xE343, 0xE3B3, 0xE423, 0xE493, 0xE503, 0xE573, 0xE5E3, 0xE654
  .hword 0xE6C4, 0xE735, 0xE7A5, 0xE816, 0xE887, 0xE8F8, 0xE969, 0xE9DA
  .hword 0xEA4B, 0xEABC, 0xEB2E, 0xEB9F, 0xEC11, 0xEC83, 0xECF5, 0xED66
  .hword 0xEDD9, 0xEE4B, 0xEEBD, 0xEF2F, 0xEFA2, 0xF014, 0xF087, 0xF0FA
  .hword 0xF16D, 0xF1E0, 0xF253, 0xF2C6, 0xF339, 0xF3AD, 0xF420, 0xF494
  .hword 0xF507, 0xF57B, 0xF5EF, 0xF663, 0xF6D7, 0xF74C, 0xF7C0, 0xF834
  .hword 0xF8A9, 0xF91E, 0xF992, 0xFA07, 0xFA7C, 0xFAF1, 0xFB66, 0xFBDC
  .hword 0xFC51, 0xFCC7, 0xFD3C, 0xFDB2, 0xFE28, 0xFE9E, 0xFF14, 0xFF8A

pitch_table_ptr:
  .word pitch_table

swi_get_pitch_table:
  add r0, r0, r0
  ldr r1, pitch_table_ptr
  // Should some protection be here?
  ldrh r0, [ r1, r0 ]
  b swi_complete

volume_table:
  .byte 0x00, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01
  .byte 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01
  .byte 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01
  .byte 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01
  .byte 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01
  .byte 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01
  .byte 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01
  .byte 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01
  .byte 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01
  .byte 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01
  .byte 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01
  .byte 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01
  .byte 0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02
  .byte 0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02
  .byte 0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02
  .byte 0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02
  .byte 0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02, 0x02
  .byte 0x02, 0x02, 0x02, 0x02, 0x02, 0x03, 0x03, 0x03
  .byte 0x03, 0x03, 0x03, 0x03, 0x03, 0x03, 0x03, 0x03
  .byte 0x03, 0x03, 0x03, 0x03, 0x03, 0x03, 0x03, 0x03
  .byte 0x03, 0x03, 0x03, 0x03, 0x03, 0x03, 0x03, 0x03
  .byte 0x03, 0x03, 0x04, 0x04, 0x04, 0x04, 0x04, 0x04
  .byte 0x04, 0x04, 0x04, 0x04, 0x04, 0x04, 0x04, 0x04
  .byte 0x04, 0x04, 0x04, 0x04, 0x04, 0x04, 0x04, 0x04
  .byte 0x05, 0x05, 0x05, 0x05, 0x05, 0x05, 0x05, 0x05
  .byte 0x05, 0x05, 0x05, 0x05, 0x05, 0x05, 0x05, 0x05
  .byte 0x05, 0x06, 0x06, 0x06, 0x06, 0x06, 0x06, 0x06
  .byte 0x06, 0x06, 0x06, 0x06, 0x06, 0x06, 0x06, 0x06
  .byte 0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 0x07, 0x07
  .byte 0x07, 0x07, 0x07, 0x07, 0x08, 0x08, 0x08, 0x08
  .byte 0x08, 0x08, 0x08, 0x08, 0x08, 0x08, 0x08, 0x09
  .byte 0x09, 0x09, 0x09, 0x09, 0x09, 0x09, 0x09, 0x09
  .byte 0x09, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A, 0x0A
  .byte 0x0A, 0x0B, 0x0B, 0x0B, 0x0B, 0x0B, 0x0B, 0x0B
  .byte 0x0B, 0x0C, 0x0C, 0x0C, 0x0C, 0x0C, 0x0C, 0x0C
  .byte 0x0C, 0x0D, 0x0D, 0x0D, 0x0D, 0x0D, 0x0D, 0x0E
  .byte 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0E, 0x0F, 0x0F
  .byte 0x0F, 0x0F, 0x0F, 0x10, 0x10, 0x10, 0x10, 0x10
  .byte 0x10, 0x11, 0x11, 0x11, 0x11, 0x11, 0x12, 0x12
  .byte 0x12, 0x12, 0x12, 0x13, 0x13, 0x13, 0x13, 0x14
  .byte 0x14, 0x14, 0x14, 0x14, 0x15, 0x15, 0x15, 0x15
  .byte 0x16, 0x16, 0x16, 0x16, 0x17, 0x17, 0x17, 0x18
  .byte 0x18, 0x18, 0x18, 0x19, 0x19, 0x19, 0x19, 0x1A
  .byte 0x1A, 0x1A, 0x1B, 0x1B, 0x1B, 0x1C, 0x1C, 0x1C
  .byte 0x1D, 0x1D, 0x1D, 0x1E, 0x1E, 0x1E, 0x1F, 0x1F
  .byte 0x1F, 0x20, 0x20, 0x20, 0x21, 0x21, 0x22, 0x22
  .byte 0x22, 0x23, 0x23, 0x24, 0x24, 0x24, 0x25, 0x25
  .byte 0x26, 0x26, 0x27, 0x27, 0x27, 0x28, 0x28, 0x29
  .byte 0x29, 0x2A, 0x2A, 0x2B, 0x2B, 0x2C, 0x2C, 0x2D
  .byte 0x2D, 0x2E, 0x2E, 0x2F, 0x2F, 0x30, 0x31, 0x31
  .byte 0x32, 0x32, 0x33, 0x33, 0x34, 0x35, 0x35, 0x36
  .byte 0x36, 0x37, 0x38, 0x38, 0x39, 0x3A, 0x3A, 0x3B
  .byte 0x3C, 0x3C, 0x3D, 0x3E, 0x3F, 0x3F, 0x40, 0x41
  .byte 0x42, 0x42, 0x43, 0x44, 0x45, 0x45, 0x46, 0x47
  .byte 0x48, 0x49, 0x4A, 0x4A, 0x4B, 0x4C, 0x4D, 0x4E
  .byte 0x4F, 0x50, 0x51, 0x52, 0x52, 0x53, 0x54, 0x55
  .byte 0x56, 0x57, 0x58, 0x59, 0x5A, 0x5B, 0x5D, 0x5E
  .byte 0x5F, 0x60, 0x61, 0x62, 0x63, 0x64, 0x65, 0x67
  .byte 0x68, 0x69, 0x6A, 0x6B, 0x6D, 0x6E, 0x6F, 0x71
  .byte 0x72, 0x73, 0x75, 0x76, 0x77, 0x79, 0x7A, 0x7B
  .byte 0x7D, 0x7E, 0x7F, 0x20, 0x21, 0x21, 0x21, 0x22
  .byte 0x22, 0x23, 0x23, 0x23, 0x24, 0x24, 0x25, 0x25
  .byte 0x26, 0x26, 0x26, 0x27, 0x27, 0x28, 0x28, 0x29
  .byte 0x29, 0x2A, 0x2A, 0x2B, 0x2B, 0x2C, 0x2C, 0x2D
  .byte 0x2D, 0x2E, 0x2E, 0x2F, 0x2F, 0x30, 0x30, 0x31
  .byte 0x31, 0x32, 0x33, 0x33, 0x34, 0x34, 0x35, 0x36
  .byte 0x36, 0x37, 0x37, 0x38, 0x39, 0x39, 0x3A, 0x3B
  .byte 0x3B, 0x3C, 0x3D, 0x3E, 0x3E, 0x3F, 0x40, 0x40
  .byte 0x41, 0x42, 0x43, 0x43, 0x44, 0x45, 0x46, 0x47
  .byte 0x47, 0x48, 0x49, 0x4A, 0x4B, 0x4C, 0x4D, 0x4D
  .byte 0x4E, 0x4F, 0x50, 0x51, 0x52, 0x53, 0x54, 0x55
  .byte 0x56, 0x57, 0x58, 0x59, 0x5A, 0x5B, 0x5C, 0x5D
  .byte 0x5E, 0x5F, 0x60, 0x62, 0x63, 0x64, 0x65, 0x66
  .byte 0x67, 0x69, 0x6A, 0x6B, 0x6C, 0x6D, 0x6F, 0x70
  .byte 0x71, 0x73, 0x74, 0x75, 0x77, 0x78, 0x79, 0x7B
  .byte 0x7C, 0x7E, 0x7E, 0x40, 0x41, 0x42, 0x43, 0x43
  .byte 0x44, 0x45, 0x46, 0x47, 0x47, 0x48, 0x49, 0x4A
  .byte 0x4B, 0x4C, 0x4C, 0x4D, 0x4E, 0x4F, 0x50, 0x51
  .byte 0x52, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59
  .byte 0x5A, 0x5B, 0x5C, 0x5D, 0x5E, 0x5F, 0x60, 0x61
  .byte 0x62, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69, 0x6B
  .byte 0x6C, 0x6D, 0x6E, 0x70, 0x71, 0x72, 0x74, 0x75
  .byte 0x76, 0x78, 0x79, 0x7B, 0x7C, 0x7D, 0x7E, 0x40
  .byte 0x41, 0x42, 0x42, 0x43, 0x44, 0x45, 0x46, 0x46
  .byte 0x47, 0x48, 0x49, 0x4A, 0x4B, 0x4B, 0x4C, 0x4D
  .byte 0x4E, 0x4F, 0x50, 0x51, 0x52, 0x53, 0x54, 0x55
  .byte 0x56, 0x57, 0x58, 0x59, 0x5A, 0x5B, 0x5C, 0x5D
  .byte 0x5E, 0x5F, 0x60, 0x61, 0x62, 0x63, 0x65, 0x66
  .byte 0x67, 0x68, 0x69, 0x6A, 0x6C, 0x6D, 0x6E, 0x6F
  .byte 0x71, 0x72, 0x73, 0x75, 0x76, 0x77, 0x79, 0x7A
  .byte 0x7C, 0x7D, 0x7E, 0x7F

padding_b:
  .word 0x0

swi_get_boot_procs:
  mov r0, #0x2E
  mov r1, #0x3C
  mov r2, #0xFF

  orr r0, r0, #0x0A00
  orr r1, r1, #0x2C00
  orr r2, r2, #0x0500

  b swi_complete
#endif

swi_custom_halt_post:
  mov r1, #0x4000000

#ifdef BIOS_ARM7
  strb r0, [ r1, #0x301 ]
#else
  strb r0, [ r1, #0x300 ]
#endif

  b swi_complete


interrupt_handler:
  // Save these registers, IRQ functions will be allowed to modify them w/o
  // saving.
  stmdb sp!, { r0 - r3, r12, lr }

#ifdef BIOS_ARM9
  // Get DTCM base
  mrc p15, 0, r0, cr9, cr1, 0
  bic r0, r0, #0xFF

  // Pointer to IRQ handler is in DTCM[0x3FFC]
  add r0, r0, #0x4000
#else
  // Pointer to IRQ handler is at 0x03FFFFFC (mirrored WRAM)
  mov r0, #0x4000000
#endif

  // Store return address and branch to handler
  mov lr, pc
  ldr pc, [ r0, #-4 ]

  // Return from IRQ
  ldmia sp!, { r0 - r3, r12, lr }
  subs pc, lr, #4

#ifdef BIOS_ARM7
swi_get_volume_table:
  adr r1, volume_table
  // Should some protection be here?
  ldrb r0, [ r1, r0 ]
  b swi_complete
#endif

stack_pointer_irq:
  .word 0x0380ffdc

swi_soft_reset:
  // set r0 to 0x3FFFE00 (points to stack space)
  mov r0, #0x4000000
  mov r1, #0x80
  mov r2, #0

  // Clear stack space
 0:
  str r2, [ r0, #-4 ]!
  subs r1, r1, #1
  bne 0b

  // Stack pointer base
  ldr r1, stack_pointer_irq

  // Initialize supervisor SPSR, LR, and SP (disable interrupts)
  mov r3, #0xd3
  msr CPSR_fsxc, r3
  // sp_svc = 0x0380ffdc
  mov sp, r1
  mov lr, r2
  msr SPSR_fsxc, r2

  // Initialize IRQ SPSR, LR, and SP (disable interrupts)
  mov r3, #0xd2
  msr CPSR_fsxc, r3
  // sp_irq = 0x0380ffb0
  sub sp, r1, #(0xdc - 0xb0)
  mov lr, r2
  msr SPSR_fsxc, r2

  // Initialize system SPSR, LR, and SP (enable interrupts)
  mov r3, #0x5f
  msr CPSR_fsxc, r3
  // sp = 0x0380ff00
  sub sp, r1, #0xdc

  // Set r0-r12 to 0, r0 still points to initialized stack space
  ldmia r0, { r0 - r12 }
  movs pc, lr

// Pad out

#ifdef BIOS_ARM7
.org 16384
#endif

#ifdef BIOS_ARM9
.org 4096
#endif