Implement very basic RYFS write support; cannot write past end of files

Bumps version to 0.7.0
This commit is contained in:
Ry 2023-01-20 18:50:40 -08:00
parent b96e6979ca
commit 155eed220c
3 changed files with 169 additions and 1 deletions

View File

@ -77,6 +77,7 @@ ryfs_read_whole_file: jmp [0xF0045014]
ryfs_get_size: jmp [0xF0045018]
ryfs_get_file_list: jmp [0xF004501C]
ryfs_tell: jmp [0xF0045020]
ryfs_write: jmp [0xF0045024]
; memory copy/compare jump table
copy_memory_bytes: jmp [0xF0046000]

View File

@ -3,7 +3,7 @@
org 0xF0000000
const FOX32ROM_VERSION_MAJOR: 0
const FOX32ROM_VERSION_MINOR: 6
const FOX32ROM_VERSION_MINOR: 7
const FOX32ROM_VERSION_PATCH: 0
const SYSTEM_STACK: 0x01FFF800
@ -285,6 +285,7 @@ get_rom_version:
data.32 ryfs_get_size
data.32 ryfs_get_file_list
data.32 ryfs_tell
data.32 ryfs_write
; memory copy/compare jump table
org.pad 0xF0046000

166
ryfs.asm
View File

@ -258,6 +258,172 @@ ryfs_read_whole_file:
pop r0
ret
; write specified number of bytes from the specified buffer
; THIS DOES NOT UPDATE THE TOTAL SIZE OF THE FILE; do not write past the end of a file, bad things will happen
; inputs:
; r0: number of bytes to write
; r1: pointer to file struct
; r2: pointer to source buffer
; outputs:
; none
ryfs_write:
push r0
push r1
push r2
push r3
push r4
push r5
push r10
push r11
push r12
push r31
; number_of_sectors_to_load = ceil(input r0, 506) / 506
; first, ceil the number of bytes to multiple of 506
; value_temp = value / 506
; if value % 506 != 0:
; value_temp++
; value_ceil = value_temp * 506
mov r10, r0
mov r11, r0
mov r12, 506
div r11, r12
rem r10, r12
ifnz inc r11
mul r11, r12
div r11, r12
mov r3, r11 ; r3: number_of_sectors_to_load
mov r10, r1
add r10, 3
mov r4, [r10]
mov r10, r4
mov r11, r4
mov r12, 506
div r11, r12
rem r10, r12
ifnz inc r11
mul r11, r12
div r11, r12
mov r4, r11 ; r4: number of sectors to traverse
; start_sector = traverse through linked sectors starting at file_struct.file_first_sector
push r0
push r1
push r2
mov r10, r1
; read the file's first sector into the temp buffer
movz.8 r1, [r10] ; file_disk
inc r10
movz.16 r0, [r10] ; file_first_sector
mov r31, r4
ryfs_write_traverse_sectors_loop:
mov r2, TEMP_SECTOR_BUF
call read_sector
mov r4, r0
add r2, 2 ; point to next sector number
movz.16 r0, [r2] ; load next sector number
cmp r31, 0 ; if we started at zero, then don't attempt to loop
ifnz loop ryfs_write_traverse_sectors_loop
pop r2
pop r1
pop r0
; r4: start_sector
; total_bytes_remaining = input r0
; this_sector = start_sector
; for range 0..number_of_sectors_to_load:
; load this_sector into temporary buffer
; bytes_to_load = if total_bytes_remaining >= 506
; 506
; else:
; total_bytes_remaining
; for range 0..bytes_to_load:
; load byte from temporary buffer into destination buffer
; this_sector = this_sector.next
mov r10, r0 ; r10: total_bytes_remaining
ryfs_write_sector_loop:
push r0
push r1
push r2
; read this sector into the temp buffer
mov r0, r4
movz.8 r1, [r1] ; file_disk
mov r2, TEMP_SECTOR_BUF
call read_sector
pop r2
pop r1
pop r0
; r11: bytes_to_load
cmp r10, 506
ifgteq mov r11, 506
iflt mov r11, r10
push r0
push r1
push r2
; calculate the seek offset
mov r12, r1
add r12, 3
mov r5, [r12]
rem r5, 506
; copy the sector data from the source buffer to the temp buffer
mov r0, r2
mov r1, TEMP_SECTOR_BUF
add r1, 6
add r1, r5 ; add the seek offset
mov r2, r11
call copy_memory_bytes
pop r2
pop r1
pop r0
push r0
push r1
push r2
; write this sector back out to disk
mov r0, r4
movz.8 r1, [r1] ; file_disk
mov r2, TEMP_SECTOR_BUF
call write_sector
pop r2
pop r1
pop r0
; this_sector = this_sector.next
mov r5, TEMP_SECTOR_BUF
add r5, 2
movz.16 r5, [r5]
mov r4, r5
add r2, r11
sub r10, r11
ifnz jmp ryfs_write_sector_loop
; file_struct.file_seek_offset += input r0
add r1, 3
add [r1], r0
pop r31
pop r12
pop r11
pop r10
pop r5
pop r4
pop r3
pop r2
pop r1
pop r0
ret
; get the exact size of a file
; inputs:
; r0: pointer to file struct