int13ext.c

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#include <dpmi.h>
#include <sys/farptr.h>
#include <sys/movedata.h>

#include "int13ext.h"




// returns -1 if installed,  0 otherwise
int int13ext_check()
{
  __dpmi_regs r;
  r.x.ax = 0x4100;
  r.x.bx = 0x55AA;
  r.h.dl = 0x80;
  __dpmi_int (0x13, &r);

  if (r.x.flags & 1) return 0;
  if (r.x.bx != 0xAA55) return 0;
  return -1;
}










// returns 0 if all goes ok, >0 int13 error, <0 DJGPP error
int int13ext_getdrvparams(int drv, struct driveparams* DParam)
{
  const int DP_size = sizeof(struct driveparams);
  DParam->crsize = DP_size;
  int selector, segress;
  __dpmi_regs r;

  segress = __dpmi_allocate_dos_memory((DP_size + 15) >> 4, &selector);
    if (segress == -1) return NO_CTLDOS_MEMORY;
  r.x.ax = 0x4800;
  r.h.dl = (unsigned short int) drv;
  r.x.ds = segress;
  r.x.si = 0;
  _farpokew(selector, 0, 0x1A); // init first field with the size of driveparams struct
  __dpmi_int (0x13, &r);

  dosmemget(segress << 4, DP_size, DParam);
  __dpmi_free_dos_memory(selector);

  if (r.x.flags & 1) return r.h.ah;

  return 0;
}








// returns 0 if all goes ok, >0 int13 error, <0 DJGPP error
int int13ext_read(int drv, struct driveparams *DParam, U64B block, U64B nblocks, void *buffer)
{
  struct diskaddrpacket DAP = {sizeof(struct diskaddrpacket), 0};
  int selDAP, segDAP, selBuff, segBuff, segBound;
  U64B transfd;
  U32B rdbuffsize =                // 0x8000 is default buffer size (32k)
    (nblocks * DParam->bytes_per_sect  <  0x8000)? nblocks*DParam->bytes_per_sect :0x8000;
  U32B blocks_per_buff = rdbuffsize/DParam->bytes_per_sect;

  segDAP = __dpmi_allocate_dos_memory((DAP.packetsize + 15) >> 4, &selDAP);
    if (segDAP == -1) return NO_CTLDOS_MEMORY;
  // we need to allocate memory more by 32k in order to find 64k boundary
  // while reading with int13 in DMA mode, that boundary can't be crossed
  // __dpmi_int returns 9h code in ah :
  // data boundary error (attempted DMA across 64K boundary or >80h sectors)
  segBuff = __dpmi_allocate_dos_memory(((rdbuffsize + 15) >> 4) + 0x800, &selBuff);
  if (segBuff == -1) {
    __dpmi_free_dos_memory(selDAP);
    return NO_BUFDOS_MEMORY;
  }
  // getting 64k boundary
  segBound = segBuff + 0x800 - (segBuff % 0x800);

  __dpmi_regs r;

  U64B tailblock = (nblocks/blocks_per_buff) * blocks_per_buff + block;
  for (transfd = block; transfd < block+nblocks; transfd += blocks_per_buff) {
    r.h.ah = 0x42;
    r.h.dl = (unsigned short int) drv;
    r.x.ds = segDAP;
    r.x.si = 0;

    DAP.packetsize = sizeof(struct diskaddrpacket);
    if (transfd == tailblock) blocks_per_buff = nblocks + block - transfd;
    DAP.nblocks = blocks_per_buff;
//    DAP.buffer_segment = segBuff;
    DAP.buffer_segment = segBound;
    DAP.buffer_offset = 0;
    DAP.startblock = transfd;
    dosmemput(&DAP, sizeof(DAP), segDAP << 4);

    __dpmi_int (0x13, &r);

    if (r.x.flags & 1) {  __dpmi_free_dos_memory(selBuff);
                          __dpmi_free_dos_memory(selDAP);  return r.h.ah; }

//    dosmemget(segBuff << 4, blocks_per_buff * DParam->bytes_per_sect,
    dosmemget(segBound << 4, blocks_per_buff * DParam->bytes_per_sect,
              (char *) buffer + (transfd - block)*DParam->bytes_per_sect);
    }

  __dpmi_free_dos_memory(selBuff);
  __dpmi_free_dos_memory(selDAP);
  return 0;
}









// returns 0 if all goes ok, >0 int13 error, <0 DJGPP error
int int13ext_write(int drv, struct driveparams *DParam, U64B block, U64B nblocks, void *buffer)
{
  struct diskaddrpacket DAP = {sizeof(struct diskaddrpacket), 0};
  int selDAP, segDAP, selBuff, segBuff, segBound;
  U64B transfd;
  U32B rdbuffsize =                // 0x8000 is default buffer size (32k)
    (nblocks * DParam->bytes_per_sect  <  0x8000)? nblocks*DParam->bytes_per_sect :0x8000;
  U32B blocks_per_buff = rdbuffsize/DParam->bytes_per_sect;

  segDAP = __dpmi_allocate_dos_memory((DAP.packetsize + 15) >> 4, &selDAP);
    if (segDAP == -1) return NO_CTLDOS_MEMORY;
  // we need to allocate memory more by 32k in order to find 64k boundary
  // while writing with int13 in DMA mode, that boundary can't be crossed
  // __dpmi_int returns 9h code in ah :
  // data boundary error (attempted DMA across 64K boundary or >80h sectors)
  segBuff = __dpmi_allocate_dos_memory(((rdbuffsize + 15) >> 4) + 0x800, &selBuff);
  if (segBuff == -1) {
    __dpmi_free_dos_memory(selDAP);
    return NO_BUFDOS_MEMORY;
  }
  // getting 64k boundary
  segBound = segBuff + 0x800 - (segBuff % 0x800);

  __dpmi_regs r;

  U64B tailblock = (nblocks/blocks_per_buff) * blocks_per_buff + block;
  for (transfd = block; transfd < block+nblocks; transfd += blocks_per_buff) {
    r.x.ax = 0x4300;    // write without verify 0x4302 - with
    r.h.dl = (unsigned short int) drv;
    r.x.ds = segDAP;
    r.x.si = 0;

    DAP.packetsize = sizeof(struct diskaddrpacket);  // 0x10
    if (transfd == tailblock) blocks_per_buff = nblocks + block - transfd;
    DAP.nblocks = blocks_per_buff;
//    DAP.buffer_segment = segBuff;
    DAP.buffer_segment = segBound;
    DAP.buffer_offset = 0;
    DAP.startblock = transfd;
    dosmemput(&DAP, sizeof(DAP), segDAP << 4);

    dosmemput((char *) buffer + (transfd - block)*DParam->bytes_per_sect,
              blocks_per_buff * DParam->bytes_per_sect, segBound << 4);

    __dpmi_int (0x13, &r);

    if (r.x.flags & 1) {  __dpmi_free_dos_memory(selBuff);
                          __dpmi_free_dos_memory(selDAP);  return r.h.ah; }
  }

  __dpmi_free_dos_memory(selBuff);
  __dpmi_free_dos_memory(selDAP);
  return 0;
}

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