3b1emu: src/wd279x.h@15ae2788e848 (annotated)

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src/wd279x.h@15ae2788e848 (annotated)

src/wd279x.h

Tue, 15 Jan 2013 17:02:56 +0000

author: Philip Pemberton <philpem@philpem.me.uk>
date: Tue, 15 Jan 2013 17:02:56 +0000
changeset 121: 15ae2788e848
parent 111: 4c85846b09cd
permissions: -rw-r--r--

Implement m68k_read_disassembler_* properly

The previous implementations of m68k_read_disassembler are unsuitable due to
interactions with the memory mapper. A read from memory by the DASM should not
mutate system state.

So we modify the m68k_read_disassembler_{8,16,32} functions to do the memory
mapping themselves without causing page faults (bus error exception) or
updating the page flag bits (which could really upset the kernel).

Now all we need is a debugger/disassembler...

 #ifndef _WD279X_H
 #define _WD279X_H
 #include <stdbool.h>
 #include <stddef.h>
 #include <stdint.h>
 #include <stdio.h>
 /// WD279x registers
 typedef enum {
 	WD2797_REG_STATUS		= 0,		///< Status register
 	WD2797_REG_COMMAND		= 0,		///< Command register
 	WD2797_REG_TRACK		= 1,		///< Track register
 	WD2797_REG_SECTOR		= 2,		///< Sector register
 	WD2797_REG_DATA			= 3			///< Data register
 } WD2797_REG;
 /// WD279x emulator error codes
 typedef enum {
 	WD2797_ERR_OK			= 0,		///< Operation succeeded
 	WD2797_ERR_BAD_GEOM		= -1,		///< Bad geometry, or image file too small
 	WD2797_ERR_NO_MEMORY	= -2		///< Out of memory
 } WD2797_ERR;
 typedef struct {
 	// Current track, head and sector
 	int						track, head, sector;
 	// Track and sector registers
 	int						track_reg, sector_reg;
 	// Geometry of current disc
 	int						geom_secsz, geom_spt, geom_heads, geom_tracks;
 	// IRQ status
 	bool					irq;
 	// Status of last command
 	uint8_t					status;
 	// Last command uses DRQ bit?
 	bool					cmd_has_drq;
 	// The last value written to the data register
 	uint8_t					data_reg;
 	// Last step direction. -1 for "towards zero", 1 for "away from zero"
 	int						last_step_dir;
 	// Data buffer, current DRQ pointer and length
 	uint8_t					*data;
 	size_t					data_pos, data_len;
 	// Current disc image file
 	FILE					*disc_image;
 	// Write protect flag
 	int						writeable;
 	// LBA at which to start writing
 	int						write_pos;
 	// True if a format command is in progress
 	int						formatting;
 } WD2797_CTX;
 /**
  * @brief	Initialise a WD2797 context.
  * @param	ctx		WD2797 context.
  *
  * This must be run once when the context is created.
  */
 void wd2797_init(WD2797_CTX *ctx);
 /**
  * @brief	Reset a WD2797 context.
  * @param	ctx		WD2797 context.
  *
  * This should be run if the WD2797 needs to be reset (nRST line toggled).
  */
 void wd2797_reset(WD2797_CTX *ctx);
 /**
  * Deinitialise a WD2797 context.
  * @param	ctx		WD2797 context.
  */
 void wd2797_done(WD2797_CTX *ctx);
 /**
  * @brief	Read IRQ Rising Edge status. Clears Rising Edge status if it is set.
  * @note	No more IRQs will be sent until the Status Register is read, or a new command is written to the CR.
  * @param	ctx		WD2797 context.
  */
 bool wd2797_get_irq(WD2797_CTX *ctx);
 /**
  * @brief	Read DRQ status.
  * @param	ctx		WD2797 context.
  */
 bool wd2797_get_drq(WD2797_CTX *ctx);
 /**
  * @brief	Assign a disc image to the WD2797.
  * @param	ctx		WD2797 context.
  * @param	fp		Disc image file, already opened in "r+b" mode.
  * @param	secsz	Sector size: either 128, 256, 512 or 1024.
  * @param	spt		Sectors per track.
  * @param	heads	Number of heads (1 or 2).
  * @return	Error code; WD279X_E_OK if everything worked OK.
  */
 WD2797_ERR wd2797_load(WD2797_CTX *ctx, FILE *fp, int secsz, int spt, int heads, int writeable);
 /**
  * @brief	Deassign the current image file.
  * @param	ctx		WD2797 context.
  */
 void wd2797_unload(WD2797_CTX *ctx);
 /**
  * @brief	Read WD279x register.
  * @param	ctx		WD2797 context
  * @param	addr	Register address (0, 1, 2 or 3)
  */
 uint8_t wd2797_read_reg(WD2797_CTX *ctx, uint8_t addr);
 /**
  * @brief	Write WD279X register
  * @param	ctx		WD2797 context
  * @param	addr	Register address (0, 1, 2 or 3)
  * @param	val		Value to write
  */
 void wd2797_write_reg(WD2797_CTX *ctx, uint8_t addr, uint8_t val);
 void wd2797_dma_miss(WD2797_CTX *ctx);
 #endif

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src/wd279x.h@15ae2788e848 (annotated)

src/wd279x.h