fox32rom: Add read and seek routines for RYFS
This commit is contained in:
parent
3de7fd9567
commit
3583067b23
1
boot.asm
1
boot.asm
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@ -60,7 +60,6 @@ start_boot_process_ryfs:
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mov r0, kernel_file_name
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mov r1, 0
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mov r2, KERNEL_FILE_STRUCT
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mov r3, TEMP_SECTOR_BUF
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call ryfs_open
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mov r0, KERNEL_FILE_STRUCT
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@ -54,6 +54,10 @@ menu_update_event: jmp [0xF004401C]
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; disk jump table
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read_sector: jmp [0xF0045000]
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write_sector: jmp [0xF0045004]
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ryfs_open: jmp [0xF0045008]
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ryfs_seek: jmp [0xF004500C]
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ryfs_read: jmp [0xF0045010]
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ryfs_read_whole_file: jmp [0xF0045014]
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; memory copy/compare jump table
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copy_memory_bytes: jmp [0xF0046000]
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4
main.asm
4
main.asm
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@ -192,6 +192,10 @@ get_rom_version:
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org.pad 0xF0045000
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data.32 read_sector
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data.32 write_sector
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data.32 ryfs_open
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data.32 ryfs_seek
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data.32 ryfs_read
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data.32 ryfs_read_whole_file
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; memory copy/compare jump table
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org.pad 0xF0046000
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184
ryfs.asm
184
ryfs.asm
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@ -1,19 +1,18 @@
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; RYFS routines
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; file struct:
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; file_disk: 1 byte
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; file_first_sector: 2 bytes
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; file_seek_offset: 4 bytes
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; file_reserved: 1 byte
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; open a file from a RYFS-formatted disk
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; inputs:
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; r0: pointer to file name string (8.3 format, for example "test txt" for test.txt)
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; r1: disk ID
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; r2: file struct: pointer to a blank 8 byte file struct as described below
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; r3: pointer to sector buffer
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; r2: file struct: pointer to a blank file struct
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; outputs:
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; r0: first file sector
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;
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; file struct:
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; file_disk: 1 byte
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; file_first_sector: 2 bytes
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; file_seek_offset: 4 bytes
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; file_reserved: 1 byte
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ryfs_open:
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push r1
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push r2
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@ -26,12 +25,12 @@ ryfs_open:
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push r0
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mov r0, 1
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mov r2, r3
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mov r2, TEMP_SECTOR_BUF
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call read_sector
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pop r0
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; point to the file name of the first directory entry
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mov r1, r3
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mov r1, TEMP_SECTOR_BUF
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add r1, 20
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mov r2, 11 ; compare 11 bytes
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ryfs_open_find_dir_entry_loop:
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@ -53,6 +52,165 @@ ryfs_open_found_dir_entry:
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pop r1
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ret
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; seek specified file to the specified offset
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; inputs:
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; r0: byte offset
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; r1: pointer to file struct
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; outputs:
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; none
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ryfs_seek:
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push r1
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add r1, 3
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mov [r1], r0
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pop r1
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ret
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; read specified number of bytes into the specified buffer
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; inputs:
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; r0: number of bytes to read
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; r1: pointer to file struct
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; r2: pointer to destination buffer
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; outputs:
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; none
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ryfs_read:
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push r0
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push r1
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push r2
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push r3
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push r4
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push r5
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push r10
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push r11
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push r12
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; number_of_sectors_to_load = ceil(input r0, 506) / 506
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; first, ceil the number of bytes to multiple of 506
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; value_temp = value / 506
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; if value % 506 != 0:
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; value_temp++
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; value_ceil = value_temp * 506
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mov r10, r0
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mov r11, r0
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mov r12, 506
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div r11, r12
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rem r10, r12
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ifnz inc r11
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mul r11, r12
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div r11, r12
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mov r3, r11 ; r3: number_of_sectors_to_load
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mov r10, r1
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add r10, 3
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mov r4, [r10]
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mov r10, r4
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mov r11, r4
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mov r12, 506
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div r11, r12
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rem r10, r12
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ifnz inc r11
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mul r11, r12
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div r11, r12
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mov r4, r11 ; r4: number of sectors to traverse
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; start_sector = traverse through linked sectors starting at file_struct.file_first_sector
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push r0
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push r1
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push r2
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mov r10, r1
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; read the file's first sector into the temp buffer
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movz.8 r1, [r10] ; file_disk
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inc r10
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movz.16 r0, [r10] ; file_first_sector
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mov r31, r4
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ryfs_read_traverse_sectors_loop:
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mov r2, TEMP_SECTOR_BUF
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call read_sector
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mov r4, r0
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add r2, 2 ; point to next sector number
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movz.16 r0, [r2] ; load next sector number
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cmp r31, 0 ; if we started at zero, then don't attempt to loop
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ifnz loop ryfs_read_traverse_sectors_loop
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pop r2
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pop r1
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pop r0
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; r4: start_sector
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; total_bytes_remaining = input r0
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; this_sector = start_sector
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; for range 0..number_of_sectors_to_load:
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; load this_sector into temporary buffer
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; bytes_to_load = if total_bytes_remaining >= 506
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; 506
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; else:
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; total_bytes_remaining
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; for range 0..bytes_to_load:
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; load byte from temporary buffer into destination buffer
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; this_sector = this_sector.next
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mov r10, r0 ; r10: total_bytes_remaining
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ryfs_read_sector_loop:
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push r0
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push r1
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push r2
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; read this sector into the temp buffer
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mov r0, r4
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movz.8 r1, [r1] ; file_disk
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mov r2, TEMP_SECTOR_BUF
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call read_sector
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pop r2
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pop r1
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pop r0
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; r11: bytes_to_load
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cmp r10, 506
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ifgteq mov r11, 506
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iflt mov r11, r10
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push r0
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push r1
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push r2
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; calculate the seek offset
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mov r12, r1
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add r12, 3
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mov r5, [r12]
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rem r5, 506
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; copy the sector data to the destination buffer
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mov r0, TEMP_SECTOR_BUF
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add r0, 6
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add r0, r5 ; add the seek offset
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mov r1, r2
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mov r2, r11
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call copy_memory_bytes
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pop r2
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pop r1
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pop r0
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dec r10
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ifnz jmp ryfs_read_sector_loop
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; file_struct.file_seek_offset += input r0
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add r1, 3
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add [r1], r0
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pop r12
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pop r11
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pop r10
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pop r5
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pop r4
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pop r3
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pop r2
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pop r1
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pop r0
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ret
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; read a whole file into the specified buffer
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; FIXME: this will always load a multiple of 506 bytes, even if the file is smaller
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; inputs:
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@ -60,12 +218,6 @@ ryfs_open_found_dir_entry:
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; r1: pointer to destination buffer
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; outputs:
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; none
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;
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; file struct:
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; file_disk: 1 byte
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; file_first_sector: 2 bytes
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; file_seek_offset: 4 bytes
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; file_reserved: 1 byte
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ryfs_read_whole_file:
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push r0
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push r1
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