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293
study/hardware/Floppy/floppy/FDDIO.C
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293
study/hardware/Floppy/floppy/FDDIO.C
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/////////////////////////////////////
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// Demo of how to access a floppy //
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// drive without of a BIOS stuff //
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// //
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// Program uses DMA data transferr //
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/////////////////////////////////////
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////////////////////////////////
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// Compiler Borland C/C++ 3.1 //
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////////////////////////////////
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#ifdef __cplusplus
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#define __CPPARGS ...
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#else
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#define __CPPARGS
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#endif
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#include <stdio.h>
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#include <stdlib.h>
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#include <conio.h>
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#include <dos.h>
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#define CYL 0
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typedef struct _DPT_
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{
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unsigned char srt_hut;
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unsigned char dma_hlt;
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unsigned char motor_w;
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unsigned char sec_size;
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unsigned char eot;
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unsigned char gap_rw;
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unsigned char dtl;
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unsigned char gap_f;
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unsigned char fill_char;
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unsigned char hst;
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unsigned char mot_start;
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} DPT;
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DPT far *get_dpt (void);
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void fdc_out (unsigned char byte);
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int fdc_inp (void);
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void int_wait (void);
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void dma_init (void far *);
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void tdelay (int cnt);
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void interrupt IRQ6 (__CPPARGS);
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void interrupt (*oldIRQ6) (__CPPARGS);
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char buffer[512];
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static int IRQ=0;
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void main (void)
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{
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unsigned i;
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long l;
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char status[7], main_status;
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DPT _far *fdpt;
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FILE *sect;
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printf ("\n\nWork with Floppy Drive Controller\n");
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oldIRQ6 = _dos_getvect (8+6);
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_dos_setvect (8+6, IRQ6);
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// We're opening a file in order to store in it
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// the very first sector of the diskette
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sect = fopen ("!sector.dat", "wb+");
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// Getting Diskette Parameter Table pointer
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fdpt = get_dpt();
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// Turning on the motor in the "A:" drive
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// Enabling interrupts before actual turning on
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_enable();
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outp (0x3F2, 0x1C);
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// Waiting while motor speeds up
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tdelay (18);
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// Displaying contents of the controller state register
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printf ("Motor is on.\t\t");
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printf ("State: %02.2X\n", inp(0x3F4));
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// recalibrate
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fdc_out (7);
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fdc_out (0);
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int_wait();
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// We need to move drive head to the CYL track
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// "Seek" command
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fdc_out (0xf);
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// The "Seek" command needs 2 parameters:
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// a Head/Drive number and a Track number.
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// Since we're working with "A:" drive and 0 head,
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// first parameter is 0, second parameter is CYL
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fdc_out (0);
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fdc_out (CYL);
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// Displaying contents of the controller state register
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printf ("\n<<<Seeking>>> \t\t");
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printf ("State: %02.2X\n", inp(0x3F4));
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// Interrupt notifies us about operation end
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int_wait();
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// Delay for head positioning
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tdelay (5);
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// In order to check the result of the "Seek" command
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// we're sending "Read Interrupt State" command
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// Displaying ST0 register and number of a track after
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// "Seek" command execution PCN
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fdc_out (0x8);
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printf ("Interrupt state:\t");
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printf (" ST0: %02.2X, \t", fdc_inp());
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printf ("PCN: %02.2X\n", fdc_inp());
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// For more detailed info of FDC state
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// we're sending "Read Media/Drive State" command,
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// displaying ST3 register
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fdc_out (4);
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fdc_out (0);
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printf ("Media/Drive state:\t ST3: %02.2X\n", fdc_inp());
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// Setting speed of data transfer to 500 KB/sec
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outp (0x3F7, 0);
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// DMA initialization
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dma_init ((void far *)buffer);
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// "Read Data" command
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fdc_out (0x66);
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fdc_out (0x0); // drive 0, head 0
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fdc_out (CYL); // track CYL
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fdc_out (0); // head 0
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fdc_out (1); // sector no 1
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// Sending some technical info to FDC.
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// This info may be obtained form the Diskette Parameter Table.
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// Parameters are:
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// - sector size;
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// - last sector on a track;
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// - gap length;
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// - number of bytes to be read/write
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fdc_out (fdpt->sec_size);
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fdc_out (fdpt->eot);
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fdc_out (fdpt->gap_rw);
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fdc_out (fdpt->dtl);
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// Waiting for interrupt (end of operation)
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int_wait();
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// Getting and displaying results of
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// the "Read Data" command
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printf ("\n<<<Reading a sector>>> \n");
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printf (" State bytes (ST0,ST1,ST2,C,H,R,N):\n");
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for(i=0; i<7; i++) printf("%02.2X\t", (char) fdc_inp());
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printf("\n");
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// Saving sector to the file
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for(i=0; i<512; i++) fputc (buffer[i],sect);
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fclose (sect);
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// Turning motor off
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outp (0x3F2, 0xC);
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lll:
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_dos_setvect (8+6, oldIRQ6);
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}
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// Writes a byte to FDC
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void fdc_out (unsigned char parm)
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{
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asm mov dx,3F4h
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loop_fdc_out:
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asm in al,dx
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asm test al,80h // Is controller ready?
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asm jz loop_fdc_out // No, waiting...
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asm inc dx
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asm mov al, parm // Writing the byte
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asm out dx, al
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}
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// Reads a byte from FDC
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int fdc_inp (void)
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{
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asm mov dx,3F4h
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loop_fdc_inp:
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asm in al,dx
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asm test al,80h // Is controller ready?
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asm jz loop_fdc_inp // No, waiting...
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asm inc dx
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asm in al, dx // Reading a byte
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return _AL;
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}
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// Waits for an interrupt generated by FDC
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void int_wait (void) {
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_enable();
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while (IRQ==0) {};
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IRQ = 0;
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}
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void interrupt IRQ6 (__CPPARGS) {
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IRQ = 1;
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outportb (0x20, 0x20);
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}
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// DMA initialization routine
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void dma_init (void far *buf)
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{
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unsigned long f_adr;
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unsigned sg, of;
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// Computing 24-bit address for the data buffer
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f_adr = ((unsigned long)FP_SEG(buf) << 4)
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+ (unsigned long)FP_OFF(buf);
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// Splitting the address into a page number
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// and an offset
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sg = (f_adr >> 16) & 0xff;
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of = f_adr & 0xffff;
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// Disabling ints during DMA programming
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_disable();
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asm mov al,46h // FDC read data command
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asm out 12,al // We're working with 16-bit ports.
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// Next byte sent to 16-bit port is less significiant
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asm out 11,al // DMA mode
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asm mov ax,of // Buffer offset LSB
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asm out 4,al
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asm mov al,ah // Buffer offset MSB
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asm out 4,al
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asm mov ax,sg // Page number
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asm out 81h,al
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asm mov ax,511 // Data length
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asm out 5,al
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asm mov al,ah
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asm out 5,al
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asm mov al,2 // channel 2 enabled
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asm out 10,al
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// It's now safe to enable ints
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_enable();
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}
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// This routine returns a Diskette Parameter Table address
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DPT far *get_dpt(void)
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{
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void far * far *ptr;
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ptr = (void far * far *)MK_FP(0x0, 0x78);
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return (DPT far*)(*ptr);
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}
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// This routine waits for cnt timer ticks.
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// Timer frequency is 18.2 Hz
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void tdelay (int cnt)
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{
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asm push bx
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asm push dx
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asm push si
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asm mov si, cnt
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asm mov ah, 0
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asm int 1ah
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asm mov bx, dx
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asm add bx, si
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delay_loop:
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asm int 1ah
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asm cmp dx, bx
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asm jne delay_loop
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asm pop si
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asm pop dx
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asm pop bx
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}
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