159 lines
2.7 KiB
NASM
159 lines
2.7 KiB
NASM
; virtual filesystem routines
|
|
|
|
; file struct for file:
|
|
; file_disk: 1 byte
|
|
; file_first_sector: 2 bytes
|
|
; file_seek_offset: 4 bytes
|
|
; file_system_type: 1 byte (0x00 for RYFS)
|
|
|
|
; file struct for stream:
|
|
; file_reserved_1: 1 byte
|
|
; file_reserved_2: 2 bytes
|
|
; file_reserved_4: 4 bytes
|
|
; file_system_type: 1 byte (0x01 for stream)
|
|
; file_read_call: 4 bytes
|
|
; file_write_call: 4 bytes
|
|
|
|
; open a file from a RYFS-formatted disk
|
|
; inputs:
|
|
; r0: pointer to file name string (8.3 format, for example "test txt" for test.txt)
|
|
; r1: disk ID
|
|
; r2: file struct: pointer to a blank file struct
|
|
; outputs:
|
|
; r0: first file sector, or zero if file wasn't found
|
|
open:
|
|
jmp ryfs_open
|
|
|
|
; seek specified file to the specified offset
|
|
; inputs:
|
|
; r0: byte offset
|
|
; r1: pointer to file struct
|
|
; outputs:
|
|
; none
|
|
seek:
|
|
push r1
|
|
add r1, 7
|
|
cmp.8 [r1], 0x00
|
|
pop r1
|
|
ifz jmp ryfs_seek
|
|
ret
|
|
|
|
; get the seek offset of the specified file
|
|
; inputs:
|
|
; r0: pointer to file struct
|
|
; outputs:
|
|
; r0: byte offset
|
|
tell:
|
|
push r0
|
|
add r0, 7
|
|
cmp.8 [r0], 0x00
|
|
pop r0
|
|
ifz jmp ryfs_tell
|
|
ret
|
|
|
|
; read specified number of bytes into the specified buffer
|
|
; inputs:
|
|
; r0: number of bytes to read
|
|
; r1: pointer to file struct
|
|
; r2: pointer to destination buffer
|
|
; outputs:
|
|
; r0: number of bytes left to read (streams can read short)
|
|
read:
|
|
push r3
|
|
push r1
|
|
add r1, 7
|
|
movz.8 r3, [r1]
|
|
pop r1
|
|
cmp.8 r3, 0x00
|
|
ifz pop r3
|
|
ifz jmp ryfs_read
|
|
cmp.8 r3, 0x01
|
|
ifz pop r3
|
|
ifz jmp stream_read
|
|
pop r3
|
|
ret
|
|
stream_read:
|
|
push r1
|
|
push r2
|
|
|
|
stream_read_loop:
|
|
call stream_read_char
|
|
call yield_task
|
|
|
|
cmp.8 [r2], 0
|
|
ifz jmp stream_read_out
|
|
|
|
inc r2
|
|
dec r0
|
|
ifnz jmp stream_read_loop
|
|
|
|
stream_read_out:
|
|
pop r2
|
|
pop r1
|
|
ret
|
|
|
|
stream_read_char:
|
|
push r0
|
|
push r1
|
|
push r2
|
|
|
|
; call [file_read_call]
|
|
add r1, 8
|
|
call [r1]
|
|
|
|
; put the result into [r2]
|
|
pop r2
|
|
mov.8 [r2], r0
|
|
|
|
pop r1
|
|
pop r0
|
|
ret
|
|
|
|
; write specified number of bytes into the specified file
|
|
; inputs:
|
|
; r0: number of bytes to write
|
|
; r1: pointer to file struct
|
|
; r2: pointer to source buffer
|
|
; outputs:
|
|
; none
|
|
write:
|
|
push r3
|
|
push r1
|
|
add r1, 7
|
|
movz.8 r3, [r1]
|
|
pop r1
|
|
cmp.8 r3, 0x00
|
|
ifz pop r3
|
|
ifz jmp ryfs_write
|
|
cmp.8 r3, 0x01
|
|
ifz pop r3
|
|
ifz jmp stream_write
|
|
pop r3
|
|
ret
|
|
stream_write:
|
|
push r31
|
|
push r2
|
|
|
|
mov r31, r0 ; number of bytes to write = loop count
|
|
stream_write_loop:
|
|
call stream_write_char
|
|
inc r2
|
|
loop stream_write_loop
|
|
|
|
pop r2
|
|
pop r31
|
|
ret
|
|
|
|
stream_write_char:
|
|
push r0
|
|
push r1
|
|
|
|
; call [file_write_call] with pointer to src buf in r0
|
|
add r1, 12
|
|
mov r0, r2
|
|
call [r1]
|
|
|
|
pop r1
|
|
pop r0
|
|
ret
|