/
disk.asm
171 lines (138 loc) · 3.02 KB
/
disk.asm
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; disk routines
const TEMP_SECTOR_BUF: 0x01FFF808
const RAMDISK_START: 0x03800000
; read a sector into the specified memory buffer
; inputs:
; r0: sector number
; r1: disk ID
; r2: sector buffer (512 bytes)
; outputs:
; none
read_sector:
cmp.8 r1, 4
ifz jmp read_romdisk_sector
cmp.8 r1, 5
ifz jmp read_ramdisk_sector
push r3
push r4
mov r3, 0x80002000 ; command to set the location of the buffer
mov r4, 0x80003000 ; command to read a sector from a disk into the buffer
or.8 r4, r1 ; set the disk ID
out r3, r2 ; set the memory buffer location
out r4, r0 ; read the sector into memory
pop r4
pop r3
ret
; read a sector from the romdisk into the specified memory buffer
; inputs:
; r0: sector number
; r2: sector buffer (512 bytes)
; outputs:
; none
read_romdisk_sector:
push r0
push r1
push r2
; source pointer
mul r0, 512
add r0, romdisk_image
; destination pointer
mov r1, r2
; copy 512 bytes
mov r2, 512
call copy_memory_bytes
pop r2
pop r1
pop r0
ret
; read a sector from the ramdisk into the specified memory buffer
; inputs:
; r0: sector number
; r2: sector buffer (512 bytes)
; outputs:
; none
read_ramdisk_sector:
push r0
push r1
push r2
; source pointer
mul r0, 512
add r0, RAMDISK_START
; destination pointer
mov r1, r2
; copy 512 bytes
mov r2, 512
call copy_memory_bytes
pop r2
pop r1
pop r0
ret
; check if a RYFS image is included as a romdisk
; inputs:
; none
; outputs:
; Z flag: set if available, reset if not
is_romdisk_available:
push r0
mov r0, romdisk_image
add r0, 514
cmp.16 [r0], 0x5952
pop r0
ret
; check if a RYFS filesystem is initialized on the ramdisk
; inputs:
; none
; outputs:
; Z flag: set if available, reset if not
is_ramdisk_formatted:
push r0
mov r0, RAMDISK_START
add r0, 514
cmp.16 [r0], 0x5952
pop r0
ret
; write a sector from the specified memory buffer
; inputs:
; r0: sector number
; r1: disk ID
; r2: sector buffer (512 bytes)
; outputs:
; none
write_sector:
cmp.8 r1, 4
ifz ret
cmp.8 r1, 5
ifz jmp write_ramdisk_sector
push r3
push r4
mov r3, 0x80002000 ; command to set the location of the buffer
mov r4, 0x80004000 ; command to write a sector to a disk from the buffer
or.8 r4, r1 ; set the disk ID
out r3, r2 ; set the memory buffer location
out r4, r0 ; write the sector from memory
pop r4
pop r3
ret
; write a sector to ramdisk from the specified memory buffer
; inputs:
; r0: sector number
; r2: sector buffer (512 bytes)
; outputs:
; none
write_ramdisk_sector:
push r0
push r1
push r2
; destination pointer
mov r1, r0
mul r1, 512
add r1, RAMDISK_START
; source pointer
mov r0, r2
; copy 512 bytes
mov r2, 512
call copy_memory_bytes
pop r2
pop r1
pop r0
ret