core: add BFile syscalls

include/gint/bfile.h

@@ -0,0 +1,81 @@
+//---
+//	gint:bfile - BFile interface
+//
+//	The system's file system is a nightmare and the risk of corrupting it
+//	or the flash by driving it manually is too great to risk. This module
+//	interfaces with the BFile syscalls for file management.
+//---
+
+#ifndef GINT_BFILE
+#define GINT_BFILE
+
+#include <stdint.h>
+
+/* BFile_Remove(): Remove a file
+   Also works if the file does not exist.
+
+   @file  FONTCHARACTER file path
+   Returns a BFile error code. */
+int BFile_Remove(uint16_t const *file);
+
+/* BFile_Create(): Create a new entry
+   The file or directory must not exist. For a file the size pointer must point
+   to the desired file size (which is fixed), for a folder it is ignored.
+
+   @file  FONTCHARACTER file path
+   @type  Entry type
+   @size  Pointer to file size if [type = BFile_File], ignored otherwise
+   Returns a BFile error code. */
+enum BFile_EntryType
+{
+	BFile_File	= 1,
+	BFile_Folder	= 5,
+};
+int BFile_Create(uint16_t const *file, enum BFile_EntryType type, int *size);
+
+/* BFile_Open(): Open an existing file
+   The file must exist.
+
+   @file  FONTCHARACTER file path
+   @mode  Desired access mode
+   Returns a file descriptor on success, or a negative BFile error code. */
+enum BFile_OpenMode
+{
+	BFile_ReadOnly	= 0x01,
+	BFile_WriteOnly	= 0x02,
+	BFile_ReadWrite	= BFile_ReadOnly | BFile_WriteOnly,
+};
+int BFile_Open(uint16_t const *file, enum BFile_OpenMode mode);
+
+/* BFile_Close(): Close a file descriptor
+   @fd  Open file descriptor
+   Returns a BFile error code. */
+int BFile_Close(int fd);
+
+/* BFile_Write(): Write data to an open file
+   Second and third argument specify the data and length to write.
+
+   WARNING: The file systems has shown to become inconsistent if an odd number
+            of bytes is written with BFile_Write(). Keep it even!
+
+   @fd         File descriptor open for writing
+   @data       Data to write
+   @even_size  Size to write (must be even, yes)
+   Returns a BFile error code. */
+int BFile_Write(int fd, void const *data, int even_size);
+
+/* BFile_Read(): Read data from an open file
+   The second and third argument specify where to store and how much to read.
+   The location from where the data is read depends on [whence]:
+
+   * If [whence >= 0], it is taken as an absolute location within the file;
+   * If [whence == -1], BFile_Read() reads from the current position.
+
+   @fd      File descriptor open for reading
+   @data    Buffer of at least [size] bytes to store data to
+   @size    Number of bytes to read
+   @whence  Starting position of the data to read in the file
+   Returns a BFile error code. */
+int BFile_Read(int handle, void *data, int size, int whence);
+
+#endif /* GINT_BFILE */

src/core/syscalls.S

@@ -1,9 +1,9 @@
 /*
 **	gint:core:syscalls - calls to CASIOWIN
 **
-**	This files can be seen as a list of everywhere gint relies on the
+**	This file can be seen as a list of everywhere gint relies on the
 **	underlying OS. Although I wish to make gint free-standing, there are
-**	still a few hard dependencies, namely:
+**	still a few hard questions, namely:
 **	* MMU management, because doing it wrong might break the calculator.
 **	* Dynamic allocation, because we can't trash the system heap.
 **	* File system, because it's a mess and we might ruin the ROM.
@@ -16,6 +16,13 @@
 .global ___realloc
 /* OS version, for debugging purposes */
 .global ___os_version
+/* Bfile calls */
+.global	_BFile_Remove
+.global	_BFile_Create
+.global	_BFile_Open
+.global	_BFile_Close
+.global	_BFile_Write
+.global	_BFile_Read
 
 .section ".pretext"
 
@@ -30,6 +37,56 @@ ___os_version:
 	nop
 1:	.long	0x02ee
 
+/* BFile driver */
+
+# int BFile_Remove(const uint16_t *file)
+_BFile_Remove:
+	mov.l	1f, r0
+	mov.l	syscall_table, r1
+	jmp	@r1
+	mov	#0, r5
+1:	.long	0x0439
+
+# int BFile_Create(uint16_t *file, enum { file = 1, folder = 5 }, int *size)
+_BFile_Create:
+	mov.l	1f, r0
+	mov.l	syscall_table, r1
+	jmp	@r1
+	nop
+1:	.long	0x0434
+
+# int BFile_Open(const uint16_t *file, int mode)
+_BFile_Open:
+	mov.l	1f, r0
+	mov.l	syscall_table, r1
+	jmp	@r1
+	mov	#0, r6
+1:	.long	0x042c
+
+# int BFile_Close(int handle)
+_BFile_Close:
+	mov.l	1f, r0
+	mov.l	syscall_table, r1
+	jmp	@r1
+	nop
+1:	.long	0x042d
+
+# int BFile_Write(int handle, const void *ram_buffer, int even_size)
+_BFile_Write:
+	mov.l	1f, r0
+	mov.l	syscall_table, r1
+	jmp	@r1
+	nop
+1:	.long	0x0435
+
+# int BFile_Read(int handle, void *ram_buffer, int size, int whence)
+_BFile_Read:
+	mov.l	1f, r0
+	mov.l	syscall_table, r1
+	jmp	@r1
+	nop
+1:	.long	0x0432
+
 syscall_table:
 	.long	0x80010070