fox32rom: Start implementing RYFS support
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Ry
parent
e7c0caafaf
commit
5df841f061
23
boot.asm
23
boot.asm
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@ -1,6 +1,9 @@
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; disk booting routines
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; these are only used during booting, they are not exposed via the jump table
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const KERNEL_FILE_STRUCT: 0x01FFF800 ; kernel.bin file struct is right above the system stack
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kernel_file_name: data.str "kernel bin" data.8 0
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; read disk 0 and attempt to figure out what type of disk it is, and load the correct binary into memory
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; inputs:
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; r0: disk size (bytes)
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@ -18,13 +21,18 @@ start_boot_process:
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mov r3, 0x80003000 ; command to read a sector from disk 0 into memory
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mov r4, 0x80002000 ; command to set the location of the buffer
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; first, check to see if this is a FAT-formatted disk
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; first, check to see if this is a FAT-formatted disk or RYFS-formatted disk
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out r4, r2 ; set the memory buffer location
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out r3, 0 ; read sector 0 into the buffer
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cmp.8 [r2], 0xEB ; check for an x86 jmp instruction, indicating a possible FAT volume
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ifz jmp start_boot_process_fat
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cmp.8 [r2], 0xE9 ; check for an x86 jmp instruction, indicating a possible FAT volume
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ifz jmp start_boot_process_fat
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out r3, 1 ; read sector 1 into the buffer
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add r2, 2
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cmp.16 [r2], 0x5952 ; check for RYFS magic bytes
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ifz jmp start_boot_process_ryfs
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sub r2, 2
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start_boot_process_raw_binary_sector_loop:
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out r4, r2 ; set the memory buffer location
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out r3, r0 ; read the current sector into memory
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@ -33,7 +41,18 @@ start_boot_process_raw_binary_sector_loop:
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loop start_boot_process_raw_binary_sector_loop
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jmp start_boot_process_done
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start_boot_process_fat:
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;
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jmp start_boot_process_fat
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start_boot_process_ryfs:
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; open kernel.bin
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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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mov r1, 0x00000800
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call ryfs_read_whole_file
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start_boot_process_done:
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; done loading !!!
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; now clean up and jump to the loaded binary
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2
disk.asm
2
disk.asm
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@ -1,5 +1,7 @@
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; disk routines
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const TEMP_SECTOR_BUF: 0x01FFF808
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; read a sector into the specified memory buffer
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; inputs:
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; r0: sector number
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1
main.asm
1
main.asm
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@ -152,6 +152,7 @@ get_rom_version:
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#include "mouse.asm"
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#include "overlay.asm"
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#include "panic.asm"
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#include "ryfs.asm"
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#include "vsync.asm"
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111
ryfs.asm
Normal file
111
ryfs.asm
Normal file
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@ -0,0 +1,111 @@
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; RYFS routines
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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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; 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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push r10
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; r10: pointer to file struct entry
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mov r10, r2
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mov.8 [r10], r1 ; write file_disk
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inc r10
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push r0
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mov r0, 1
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mov r2, r3
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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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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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call compare_memory_bytes
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ifz jmp ryfs_open_found_dir_entry
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add r1, 16 ; point to the file name in the next directory entry
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jmp ryfs_open_find_dir_entry_loop ; FIXME: this never returns if the file wasn't found
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ryfs_open_found_dir_entry:
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sub r1, 4 ; point to first sector of this file
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mov.16 [r10], [r1] ; write file_first_sector
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add r10, 2
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mov [r10], 0 ; write file_seek_offset
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inc r10
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mov.8 [r10], 0 ; write file_reserved
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movz.16 r0, [r1]
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pop r10
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pop r2
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pop r1
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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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; r0: pointer to file struct
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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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push r2
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push r10
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push r11
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mov r10, r0
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mov r11, r1
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; read the first sector into the temp buffer
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movz.8 r1, [r0] ; file_disk
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inc r0
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movz.16 r0, [r0] ; file_first_sector
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ryfs_read_whole_file_sector_loop:
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mov r2, TEMP_SECTOR_BUF
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call read_sector
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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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mov r1, r11
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mov r2, 506
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call copy_memory_bytes
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; check to see if this is the last sector
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; FIXME: if this is the last sector, it should respect the sector size field in the header
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sub r0, 4
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cmp.16 [r0], 0
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ifz jmp ryfs_read_whole_file_last_sector
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; there are more sectors left, load them
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movz.16 r0, [r0] ; sector number
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mov r1, [r10] ; file_disk
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add r11, 506
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jmp ryfs_read_whole_file_sector_loop
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ryfs_read_whole_file_last_sector:
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pop r11
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pop r10
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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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