Difference between revisions of "83Plus:Software:usb8x/Asm Interface/MSD"
From WikiTI
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| + | == Mass Storage Driver Assembly Interface == | ||
| + | |||
The mass storage driver works through a series of U_CALL entry points, much like the HID driver. | The mass storage driver works through a series of U_CALL entry points, much like the HID driver. | ||
| − | It requires two RAM buffers, one for internal use and one for a sector buffer. File handles used for opened files (explained later) also require around 27 bytes. The size of all three of these buffers can be obtained through the [[MSDVersion]] U_CALL. The size of the internal buffer is typically 254 bytes and the sector buffer is 512 bytes. | + | It requires two RAM buffers, one for internal use and one for a sector buffer. File handles used for opened files (explained later) also require around 27 bytes. The size of all three of these buffers can be obtained through the [[/MSDVersion|MSDVersion]] U_CALL. The size of the internal buffer is typically 254 bytes and the sector buffer is 512 bytes. |
| − | The entry point which requires these buffers is the [[MSD_Initialize]] U_CALL. Its memory can be dynamically allocated to appBackUpScreen (taking up practically all of it) with the code below: | + | The entry point which requires these buffers is the [[/MSD_Initialize|MSD_Initialize]] U_CALL. Its memory can be dynamically allocated to appBackUpScreen (taking up practically all of it) with the code below: |
<code> | <code> | ||
| Line 15: | Line 17: | ||
</code> | </code> | ||
| − | For file system operations, you will then make calls to [[UFI_Initialize]] and [[FAT_Initialize]]. All | + | For file system operations, you will then make calls to [[/UFI_Initialize|UFI_Initialize]] and [[/FAT_Initialize|FAT_Initialize]]. All entry points will return with the carry flag set if there are problems, with more detailed information in offErrorCode. |
| − | If all three | + | If all three of these U_CALLs succeed, the following entry points can then be called. |
== Entry Points == | == Entry Points == | ||
Revision as of 21:54, 16 August 2006
Mass Storage Driver Assembly Interface
The mass storage driver works through a series of U_CALL entry points, much like the HID driver.
It requires two RAM buffers, one for internal use and one for a sector buffer. File handles used for opened files (explained later) also require around 27 bytes. The size of all three of these buffers can be obtained through the MSDVersion U_CALL. The size of the internal buffer is typically 254 bytes and the sector buffer is 512 bytes.
The entry point which requires these buffers is the MSD_Initialize U_CALL. Its memory can be dynamically allocated to appBackUpScreen (taking up practically all of it) with the code below:
U_CALL MSDVersion ld de,appBackUpScreen push de add hl,de ex de,hl pop hl U_CALL MSD_Initialize
For file system operations, you will then make calls to UFI_Initialize and FAT_Initialize. All entry points will return with the carry flag set if there are problems, with more detailed information in offErrorCode.
If all three of these U_CALLs succeed, the following entry points can then be called.
Entry Points
| MSDVersion | Gets mass storage driver version and memory requirements |
| MSD_Initialize | Initializes mass storage driver |
| UFI_Initialize | Initializes connected mass storage device for sector read/write operations |
| UFI_Read | Reads sector at (MSDLBA) address into sector buffer |
| UFI_Write | Writes memory in sector buffer to (MSDLBA) address |
| FAT_Initialize | Initializes connected mass storage device for FAT16 file system operations |
| DOS_openFile | Opens a file and populates file handle with important information |
| DOS_fileSeek | Sets seek pointer for file handle to specified offset |
| DOS_fileRead | Read bytes from a file |
| DOS_fileWrite | Write bytes to a file and grow if necessary |
| DOS_createFile | Create new file in specified directory with size 0 |
| DOS_createDirectory | Create new subdirectory in specified directory |
| DOS_renameFileEntry | Rename specified file or folder |
| DOS_deleteFileEntry | Delete file or folder (including contents) |
| DOS_countFilesInDir | Get number of files/folders in specified directory |
| DOS_getNextFile | Get first/next file in specified directory |
| DOS_getFileSize | Get size of file |
| DOS_getDirEntry | Get directory entry for specified file/folder |
| FAT_nameConvertTo11 | Convert name to 11-character format (ex. "README TXT") |
| FAT_nameConvertFrom11 | Convert name to ASCIIZ format (ex. "readme.txt") |
| FAT_lookupPath | Find whether specified file/directory exists |
| FAT_findFileInCluster | Get directory entry for a file in specified folder |
| FAT_getStartingCluster | Get starting cluster of specified directory |
