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|
/*****************************************************************************/
/* */
/* Module: SBDRV */
/* Purpose: Sound Blaster DAC DMA Driver V1.2 */
/* Author(s): Ron Fries, Neil Bradley and Bradford Mott */
/* */
/* 02/20/97 - Initial Release */
/* */
/* 08/19/97 - V1.1 - Corrected problem with the auto-detect of older SB */
/* cards and problem with DSP shutdown which left the auto-init */
/* mode active. Required creating a function to reset the DSP. */
/* Also, added checks on the BLASTER settings to verify they */
/* are possible values for either SB or SB compatibles. */
/* Added several helpful information/error messages. These can */
/* be disabled by removing the SBDRV_SHOW_ERR definition. */
/* */
/* 12/24/97 - V1.2 - Added support for DJGPP (by Bradford Mott). */
/* */
/* 05/01/98 - V1.3 - Added timeout handling and ResetDSP (by Robert Golias) */
/* */
/*****************************************************************************/
/* */
/* License Information and Copyright Notice */
/* ======================================== */
/* */
/* SBDrv is Copyright(c) 1997-1998 by Ron Fries, Neil Bradley and */
/* Bradford Mott */
/* */
/* This library is free software; you can redistribute it and/or modify it */
/* under the terms of version 2 of the GNU Library General Public License */
/* as published by the Free Software Foundation. */
/* */
/* This library is distributed in the hope that it will be useful, but */
/* WITHOUT ANY WARRANTY; without even the implied warranty of */
/* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library */
/* General Public License for more details. */
/* To obtain a copy of the GNU Library General Public License, write to the */
/* Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
/* */
/* Any permitted reproduction of these routines, in whole or in part, must */
/* bear this legend. */
/* */
/*****************************************************************************/
#ifdef DJGPP
#include <go32.h>
#include <dpmi.h>
#include <sys/movedata.h>
#endif /* */
#include <dos.h>
#include <stdlib.h>
#include <ctype.h>
#include <string.h>
#include <conio.h>
#include <time.h>
#include <stdio.h>
#include "sbdrv.h"
#define DSP_RESET 0x06
#define DSP_READ 0x0a
#define DSP_WRITE 0x0c
#define DSP_ACK 0x0e
#define DMA_BASE 0x00
#define DMA_COUNT 0x01
#define DMA_MASK 0x0a
#define DMA_MODE 0x0b
#define DMA_FF 0x0c
#define MASTER_VOLUME 0x22
#define LINE_VOLUME 0x2e
#define FM_VOLUME 0x26
/* declare local global variables */
#ifdef DJGPP
static int theDOSBufferSegment;
static int theDOSBufferSelector;
#endif /* */
static uint8 *Sb_buffer;
static uint16 Sb_buf_size = 200;
static uint16 Sb_offset;
static uint16 Playback_freq;
static uint8 Sb_init = 0;
static uint8 Count_low;
static uint8 Count_high;
static uint16 IOaddr = 0x220;
static uint16 Irq = 7;
static uint16 Dma = 1;
static uint8 DMAmode = AUTO_DMA;
/*static */ uint8 DMAcount;
static void (*FillBuffer) (uint8 * buf, uint16 buf_size);
#ifdef DJGPP
static _go32_dpmi_seginfo OldIntVectInfo;
static _go32_dpmi_seginfo NewIntVectInfo;
#else /* */
static void (__interrupt * OldIntVect) (void);
#endif /* */
/* function prototypes */
#ifdef DJGPP
static void newIntVect(void);
#else /* */
static void interrupt newIntVect(void);
#endif /* */
static void setNewIntVect(uint16 irq);
static void setOldIntVect(uint16 irq);
static void dsp_out(uint16 port, uint8 val);
static uint8 hextodec(char c);
static void logErr(char *st);
static uint8 getBlasterEnv(void);
static uint8 dsp_in(uint16 port);
/*****************************************************************************/
/* */
/* Module: setNewIntVect */
/* Purpose: To set the specified interrupt vector to the sound output */
/* processing interrupt. */
/* Author: Ron Fries */
/* Date: January 1, 1997 */
/* */
/*****************************************************************************/
static void setNewIntVect(uint16 irq)
{
if (irq > 7) {
#ifdef DJGPP
_go32_dpmi_get_protected_mode_interrupt_vector(irq + 0x68,
&OldIntVectInfo);
NewIntVectInfo.pm_selector = _my_cs();
NewIntVectInfo.pm_offset = (int) newIntVect;
_go32_dpmi_allocate_iret_wrapper(&NewIntVectInfo);
_go32_dpmi_set_protected_mode_interrupt_vector(irq + 0x68,
&NewIntVectInfo);
#else /* */
OldIntVect = _dos_getvect(irq + 0x68);
_dos_setvect(irq + 0x68, newIntVect);
#endif /* */
}
else {
#ifdef DJGPP
_go32_dpmi_get_protected_mode_interrupt_vector(irq + 0x08,
&OldIntVectInfo);
NewIntVectInfo.pm_selector = _my_cs();
NewIntVectInfo.pm_offset = (int) newIntVect;
_go32_dpmi_allocate_iret_wrapper(&NewIntVectInfo);
_go32_dpmi_set_protected_mode_interrupt_vector(irq + 0x08,
&NewIntVectInfo);
#else /* */
OldIntVect = _dos_getvect(irq + 0x08);
_dos_setvect(irq + 0x08, newIntVect);
#endif /* */
}
}
/*****************************************************************************/
/* */
/* Module: setOldIntVect */
/* Purpose: To restore the original vector */
/* Author: Ron Fries */
/* Date: January 1, 1997 */
/* */
/*****************************************************************************/
static void setOldIntVect(uint16 irq)
{
if (irq > 7) {
#ifdef DJGPP
_go32_dpmi_set_protected_mode_interrupt_vector(irq + 0x68,
&OldIntVectInfo);
_go32_dpmi_free_iret_wrapper(&NewIntVectInfo);
#else /* */
_dos_setvect(irq + 0x68, OldIntVect);
#endif /* */
}
else {
#ifdef DJGPP
_go32_dpmi_set_protected_mode_interrupt_vector(irq + 0x08,
&OldIntVectInfo);
_go32_dpmi_free_iret_wrapper(&NewIntVectInfo);
#else /* */
_dos_setvect(irq + 0x08, OldIntVect);
#endif /* */
}
}
/*****************************************************************************/
/* */
/* Module: dsp_out */
/* Purpose: To send a byte to the SB's DSP */
/* Author: Ron Fries */
/* Date: September 10, 1996 */
/* */
/*****************************************************************************/
static void dsp_out(uint16 port, uint8 val)
{
uint32 timeout=60000;
/* wait for buffer to be free */
while ((timeout--) && (inp(IOaddr + DSP_WRITE) & 0x80)) {
/* do nothing */
}
/* transmit the next byte */
outp(port, val);
}
/*****************************************************************************/
/* */
/* Module: dsp_in */
/* Purpose: To read a byte from the SB's DSP */
/* Author: Ron Fries */
/* Date: January 26, 1997 */
/* */
/*****************************************************************************/
static uint8 dsp_in(uint16 port)
{
uint16 x = 10000; /* set timeout */
/* wait for buffer to be free */
while (((inp(IOaddr + 0x0E) & 0x80) == 0) && (x > 0)) {
/* decrement the timeout */
x--;
}
if (x > 0) {
/* read the data byte */
return (inp(port));
}
else {
return (0);
}
}
/*****************************************************************************/
/* */
/* Module: hextodec */
/* Purpose: Convert the input character to hex */
/* Author: Ron Fries */
/* Date: September 10, 1996 */
/* */
/*****************************************************************************/
uint8 hextodec(char c)
{
uint8 retval = 0;
c = toupper(c);
if ((c >= '0') && (c <= '9')) {
retval = c - '0';
}
else if ((c >= 'A') && (c <= 'F')) {
retval = c - 'A' + 10;
}
return (retval);
}
/*****************************************************************************/
/* */
/* Module: logErr */
/* Purpose: Displays an error message. */
/* Author: Ron Fries */
/* Date: September 24, 1996 */
/* */
/*****************************************************************************/
static void logErr(char *st)
{
#ifdef SBDRV_SHOW_ERR
printf("%s", st);
#endif /* */
}
/*****************************************************************************/
/* */
/* Module: getBlasterEnv */
/* Purpose: Read the BLASTER environment variable and set the local globals */
/* Author: Ron Fries */
/* Date: September 10, 1996 */
/* */
/*****************************************************************************/
static uint8 getBlasterEnv(void)
{
char *env;
char *ptr;
uint16 count = 0;
env = strupr(getenv("BLASTER"));
/* if the environment variable exists */
if (env) {
/* search for the address setting */
ptr = strchr(env, 'A');
if (ptr) {
/* if valid, read and convert the IO address */
IOaddr = (hextodec(ptr[1]) << 8) +
(hextodec(ptr[2]) << 4) +
(hextodec(ptr[3]));
/* verify the IO address is one of the possible SB settings */
switch (IOaddr) {
case 0x210:
case 0x220:
case 0x230:
case 0x240:
case 0x250:
case 0x260:
case 0x280:
case 0x2A0:
case 0x2C0:
case 0x2E0:
/* IO address OK so indicate one more valid item found */
count++;
break;
default:
logErr("Invalid Sound Blaster I/O address specified.\n");
logErr("Possible values are: ");
logErr("210, 220, 230, 240, 250, 260, 280, 2A0, 2C0, 2E0.\n");
}
}
else {
logErr("Unable to read Sound Blaster I/O address.\n");
}
/* search for the IRQ setting */
ptr = strchr(env, 'I');
if (ptr) {
/* if valid, read and convert the IRQ */
/* if the IRQ has two digits */
if ((ptr[1] == '1') && ((ptr[2] >= '0') && (ptr[2] <= '5'))) {
/* then convert accordingly (using decimal) */
Irq = hextodec(ptr[1]) * 10 + hextodec(ptr[2]);
}
else {
/* else convert as a single hex digit */
Irq = hextodec(ptr[1]);
}
/* verify the IRQ setting is one of the possible SB settings */
switch (Irq) {
case 2: /* two is actually the interrupt cascade for IRQs > 7 */
/* IRQ nine is the cascase for 2 */
Irq = 9;
/* IRQ OK so indicate one more valid item found */
count++;
break;
case 3:
case 4:
case 5:
case 7:
case 9:
case 10:
case 11:
case 12:
case 15:
/* IRQ OK so indicate one more valid item found */
count++;
break;
default:
logErr("Invalid Sound Blaster IRQ specified.\n");
logErr("Possible values are: ");
logErr("2, 3, 4, 5, 7, 9, 10, 11, 12, 15.\n");
}
}
else {
logErr("Unable to read Sound Blaster IRQ.\n");
}
/* search for the DMA setting */
ptr = strchr(env, 'D');
if (ptr) {
/* if valid, read and convert the DMA */
Dma = hextodec(ptr[1]);
/* verify the DMA setting is one of the possible 8-bit SB settings */
switch (Dma) {
case 0:
case 1:
case 3:
/* DMA OK so indicate one more valid item found */
count++;
break;
default:
logErr("Invalid Sound Blaster 8-bit DMA specified.\n");
logErr("Possible values are: ");
logErr("0, 1, 3.\n");
}
}
else {
logErr("Unable to read Sound Blaster DMA setting.\n");
}
}
else {
logErr("BLASTER enviroment variable not configured.");
}
return (count != 3);
}
/*****************************************************************************/
/* */
/* Module: low_malloc */
/* Purpose: To allocate memory in the first 640K of memory */
/* Author: Neil Bradley */
/* Date: December 16, 1996 */
/* */
/*****************************************************************************/
#ifdef __WATCOMC__
void dos_memalloc(unsigned short int para, unsigned short int *seg, unsigned short int *sel);
#pragma aux dos_memalloc = \
"push ecx" \
"push edx" \
"mov ax, 0100h" \
"int 31h" \
"pop ebx" \
"mov [ebx], dx" \
"pop ebx" \
"mov [ebx], ax" \
parm[bx][ecx][edx] \
modify[ax ebx ecx edx];
void dos_memfree(short int sel);
#pragma aux dos_memfree = \
"mov ax, 0101h" \
"int 31h" \
parm[dx] \
modify[ax dx];
void *low_malloc(int size)
{
unsigned short int seg;
unsigned short int i = 0;
dos_memalloc((size >> 4) + 1, &seg, &i);
return ((char *) (seg << 4));
}
#endif /* */
/*****************************************************************************/
/* */
/* Module: Set_master_volume */
/* Purpose: To set the Sound Blaster's master volume */
/* Author: Neil Bradley */
/* Date: January 1, 1997 */
/* */
/*****************************************************************************/
void Set_master_volume(uint8 left, uint8 right)
{
/* if the SB was initialized */
if (Sb_init) {
outp(IOaddr + 0x04, MASTER_VOLUME);
outp(IOaddr + 0x05, ((left & 0xf) << 4) + (right & 0x0f));
}
}
/*****************************************************************************/
/* */
/* Module: Set_line_volume */
/* Purpose: To set the Sound Blaster's line level volume */
/* Author: Neil Bradley */
/* Date: January 1, 1997 */
/* */
/*****************************************************************************/
void Set_line_volume(uint8 left, uint8 right)
{
/* if the SB was initialized */
if (Sb_init) {
outp(IOaddr + 0x04, LINE_VOLUME);
outp(IOaddr + 0x05, ((left & 0xf) << 4) + (right & 0x0f));
}
}
/*****************************************************************************/
/* */
/* Module: Set_FM_volume */
/* Purpose: To set the Sound Blaster's FM volume */
/* Author: Neil Bradley */
/* Date: January 1, 1997 */
/* */
/*****************************************************************************/
void Set_FM_volume(uint8 left, uint8 right)
{
/* if the SB was initialized */
if (Sb_init) {
outp(IOaddr + 0x04, FM_VOLUME);
outp(IOaddr + 0x05, ((left & 0xf) << 4) + (right & 0x0f));
}
}
/*****************************************************************************/
/* */
/* Module: ResetDSP */
/* Purpose: To reset the SB DSP. Returns a value of zero if unsuccessful. */
/* This function requires as input the SB base port address. */
/* Author: Ron Fries */
/* Date: August 5, 1997 */
/* */
/*****************************************************************************/
uint8 ResetDSP(uint16 ioaddr)
{
uint8 x;
uint16 y;
/* assume the init was not successful */
Sb_init = 0;
/* send a DSP reset to the SB */
outp(ioaddr + DSP_RESET, 1);
/* wait a few microsec */
x = inp(ioaddr + DSP_RESET);
x = inp(ioaddr + DSP_RESET);
x = inp(ioaddr + DSP_RESET);
x = inp(ioaddr + DSP_RESET);
/* clear the DSP reset */
outp(ioaddr + DSP_RESET, 0);
/* wait a bit until the SB indicates good status */
y = 0;
do {
x = inp(ioaddr + DSP_READ);
y++;
} while ((y < 1000) && (x != 0xaa));
/* if we were able to successfully reset the SB */
if (x == 0xaa) {
/* turn on speaker */
dsp_out(ioaddr + DSP_WRITE, 0xd1);
/* read to make sure DSP register is clear */
dsp_in(ioaddr + DSP_READ);
/* set time constant */
dsp_out(ioaddr + DSP_WRITE, 0x40);
dsp_out(ioaddr + DSP_WRITE,
(unsigned char) (256 - 1000000L / Playback_freq));
/* indicate successful initialization */
Sb_init = 1;
}
return (Sb_init);
}
/*****************************************************************************/
/* */
/* Module: OpenSB */
/* Purpose: To reset the SB and prepare all buffers and other global */
/* global variables for sound output. Allows the user to select */
/* the playback frequency, number of buffers, and size of each */
/* buffer. Returns a value of zero if unsuccessful. */
/* Author: Ron Fries */
/* Date: January 1, 1997 */
/* */
/*****************************************************************************/
uint8 OpenSB(uint16 playback_freq, uint16 buffer_size)
{
/* initialize local globals */
if (buffer_size > 0) {
Sb_buf_size = buffer_size;
}
Playback_freq = playback_freq;
/* assume the init was not successful */
Sb_init = 0;
/* attempt to read the Blaster Environment Variable */
if (getBlasterEnv() == 0) {
/* if the DSP could be successfully reset */
if (ResetDSP(IOaddr) != 0) {
/* setup the DSP interrupt service routine */
setNewIntVect(Irq);
/* Enable the interrupt used */
if (Irq > 7) {
outp(0xa1, inp(0xa1) & (~(1 << (Irq - 8))));
}
else {
outp(0x21, inp(0x21) & (~(1 << Irq)));
}
/* make sure interrupts are enabled */
_enable();
/* create a buffer to hold the data */
#ifdef __WATCOMC__
Sb_buffer = low_malloc(Sb_buf_size * 2);
#elif defined(DJGPP)
Sb_buffer = (uint8 *) malloc(Sb_buf_size * 2);
theDOSBufferSegment = __dpmi_allocate_dos_memory((Sb_buf_size * 2 + 15) >> 4,
&theDOSBufferSelector);
#else /* */
Sb_buffer = malloc(Sb_buf_size * 2);
#endif /* */
/* if we were unable to successfully allocate the buffer */
#ifdef DJGPP
if ((Sb_buffer == 0) || (theDOSBufferSegment == -1))
#else /* */
if (Sb_buffer == 0)
#endif /* */
{
logErr("Unable to allocate buffer for audio output.\n");
/* close the SB */
CloseSB();
}
}
else {
logErr("Unable to initialize the Sound Card.\n");
}
}
return (Sb_init);
}
/*****************************************************************************/
/* */
/* Module: CloseSB */
/* Purpose: Closes the SB and disables the interrupts. */
/* Author: Ron Fries */
/* Date: January 1, 1997 */
/* */
/*****************************************************************************/
void CloseSB(void)
{
#ifdef __WATCOMC__
uint32 addr;
#endif /* */
/* if the SB was initialized */
if (Sb_init) {
/* stop all DMA transfer */
Stop_audio_output();
ResetDSP(IOaddr); /*GOLDA CHANGED*/
/* turn the speaker off */
dsp_out(IOaddr + DSP_WRITE, 0xd3);
/* indicate SB no longer active */
Sb_init = 0;
/* Disable the interrupt used */
if (Irq > 7) {
outp(0xa1, inp(0xa1) | (1 << (Irq - 8)));
}
else {
outp(0x21, inp(0x21) | (1 << Irq));
}
/* restore the original interrupt routine */
setOldIntVect(Irq);
/* free any memory that had been allocated */
if (Sb_buffer != 0) {
#ifdef __WATCOMC__
addr = (uint32) Sb_buffer;
dos_memfree((uint16) (addr >> 4));
#elif defined(DJGPP)
free(Sb_buffer);
__dpmi_free_dos_memory(theDOSBufferSelector);
#else /* */
free(Sb_buffer);
#endif /* */
}
}
}
/*****************************************************************************/
/* */
/* Module: Stop_audio_output */
/* Purpose: Stops the SB's DMA transfer. */
/* Author: Ron Fries */
/* Date: January 17, 1997 */
/* */
/*****************************************************************************/
void Stop_audio_output(void)
{
/* stop any transfer that may be in progress */
/* if the SB was initialized */
if (Sb_init) {
/* halt DMA */
dsp_out(IOaddr + DSP_WRITE, 0xd0);
/* exit DMA operation */
dsp_out(IOaddr + DSP_WRITE, 0xda);
/* halt DMA */
dsp_out(IOaddr + DSP_WRITE, 0xd0);
}
}
/*****************************************************************************/
/* */
/* Module: Start_audio_output */
/* Purpose: Fills all configured buffers and outputs the first. */
/* Author: Ron Fries */
/* Date: February 20, 1997 */
/* */
/*****************************************************************************/
uint8 Start_audio_output(uint8 dma_mode,
void (*fillBuffer) (uint8 * buf, uint16 n))
{
uint8 ret_val = 1;
static uint8 pagePort[8] =
{0x87, 0x83, 0x81, 0x82};
uint8 offset_low;
uint8 offset_high;
uint8 page_no;
uint8 count_low;
uint8 count_high;
uint32 addr;
clock_t start_time;
/* if the SB initialized properly */
if (Sb_init) {
/* set the fill buffer routine */
FillBuffer = fillBuffer;
/* keep track of the DMA selection */
DMAmode = dma_mode;
/* stop any transfer that may be in progress */
Stop_audio_output();
/* fill the buffer */
FillBuffer(Sb_buffer, Sb_buf_size * 2);
#ifdef DJGPP
/* Copy data to DOS memory buffer */
dosmemput(Sb_buffer, Sb_buf_size * 2, theDOSBufferSegment << 4);
#endif /* */
/* calculate high, low and page addresses of buffer */
#ifdef __WATCOMC__
addr = (uint32) Sb_buffer;
#elif defined(DJGPP)
addr = ((uint32) theDOSBufferSegment) << 4;
#else /* */
addr = ((uint32) FP_SEG(Sb_buffer) << 4) +
(uint32) FP_OFF(Sb_buffer);
#endif /* */
Sb_offset = (uint16) (addr & 0x0ffff);
offset_low = (uint8) (addr & 0x0ff);
offset_high = (uint8) ((addr >> 8) & 0x0ff);
page_no = (uint8) (addr >> 16);
count_low = (uint8) ((Sb_buf_size * 2) - 1) & 0x0ff;
count_high = (uint8) (((Sb_buf_size * 2) - 1) >> 8) & 0x0ff;
/* program the DMAC for output transfer */
outp(DMA_MASK, 0x04 | Dma);
outp(DMA_FF, 0);
/* select auto-initialize DMA mode */
outp(DMA_MODE, 0x58 | Dma);
outp(DMA_BASE + (Dma << 1), offset_low);
outp(DMA_BASE + (Dma << 1), offset_high);
outp(pagePort[Dma], page_no);
outp(DMA_COUNT + (Dma << 1), count_low);
outp(DMA_COUNT + (Dma << 1), count_high);
outp(DMA_MASK, Dma);
/* calculate the high/low buffer size counts */
Count_low = (uint8) (Sb_buf_size - 1) & 0x0ff;
Count_high = (uint8) ((Sb_buf_size - 1) >> 8) & 0x0ff;
if (DMAmode == STANDARD_DMA) {
/* start the standard DMA transfer */
dsp_out(IOaddr + DSP_WRITE, 0x14);
dsp_out(IOaddr + DSP_WRITE, Count_low);
dsp_out(IOaddr + DSP_WRITE, Count_high);
}
else {
/* reset the DMA counter */
DMAcount = 0;
ResetDSP(IOaddr); /*GOLDA CHANGED*/
/* set the auto-initialize buffer size */
dsp_out(IOaddr + DSP_WRITE, 0x48);
dsp_out(IOaddr + DSP_WRITE, Count_low);
dsp_out(IOaddr + DSP_WRITE, Count_high);
/* and start the auto-initialize DMA transfer */
dsp_out(IOaddr + DSP_WRITE, 0x1c);
start_time = clock();
/* Delay for a bit and wait for DMAcount to change. */
/* Wait for the DMA to be called twice to make sure */
/* auto-init mode is working properly. */
while ((clock() - start_time < (int) (CLK_TCK / 2)) && (DMAcount < 2)) {
/* This routine will wait for up to 1/2 second for DMAcount */
/* to change. The value in CLK_TCK is the number of times */
/* the clock will tick in one second. */
}
/* if the auto-init DMA is not active */
if (DMAcount < 2) {
/* Reset the SB DSP */
ResetDSP(IOaddr);
/* then try again with STANDARD_DMA */
Start_audio_output(STANDARD_DMA, fillBuffer);
}
}
ret_val = 0;
}
return (ret_val);
}
/*****************************************************************************/
/* */
/* Module: newIntVect */
/* Purpose: The interrupt vector to handle the DAC DMAC completed interrupt */
/* Sends the next buffer to the SB and re-fills the current buffer. */
/* Author: Ron Fries */
/* Date: January 1, 1997 */
/* */
/*****************************************************************************/
#ifdef DJGPP
static void newIntVect(void)
#else /* */
static void interrupt newIntVect(void)
#endif /* */
{
uint16 addr;
if (DMAmode == STANDARD_DMA) {
/* restart standard DMA transfer */
dsp_out(IOaddr + DSP_WRITE, 0x14);
dsp_out(IOaddr + DSP_WRITE, Count_low);
dsp_out(IOaddr + DSP_WRITE, Count_high);
}
DMAcount++;
/* acknowledge the DSP interrupt */
inp(IOaddr + DSP_ACK);
/* determine the current playback position */
addr = inp(DMA_BASE + (Dma << 1)); /* get low byte ptr */
addr |= inp(DMA_BASE + (Dma << 1)) << 8; /* and high byte ptr */
addr -= Sb_offset; /* subtract the offset */
/* if we're currently playing the first half of the buffer */
if (addr < Sb_buf_size) {
/* reload the second half of the buffer */
FillBuffer(Sb_buffer + Sb_buf_size, Sb_buf_size);
#ifdef DJGPP
/* Copy data to DOS memory buffer */
dosmemput(Sb_buffer + Sb_buf_size, Sb_buf_size,
(theDOSBufferSegment << 4) + Sb_buf_size);
#endif /* */
}
else {
/* else reload the first half of the buffer */
FillBuffer(Sb_buffer, Sb_buf_size);
#ifdef DJGPP
/* Copy data to DOS memory buffer */
dosmemput(Sb_buffer, Sb_buf_size, theDOSBufferSegment << 4);
#endif /* */
}
/* indicate end of interrupt */
outp(0x20, 0x20);
if (Irq > 7) {
outp(0xa0, 0x20);
}
}
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