void pch(unsigned char c)
{
if ((x_pos >= 0) && (x_pos < screen_w))
_farpokew(dos_seg, SCRN_ADDR(x_pos, y_pos), (attrib<<8)|c);
x_pos++;
}
GRIP_bool8 GrLink(GRIP_BUF image, GRIP_VALUE size)
{
unsigned short img_off; /* Offset of binary image */
unsigned short img_size; /* Size of binary image */
unsigned char img_check; /* Checksum of binary image */
unsigned long memory; /* Image memory */
GRIP_BUF_C header; /* Image header */
GRIP_BUF_C core; /* Image core */
int i;
/* Check for duplicate GrLink calls */
if (GRIP_Thunked) return 0;
/* Sanity check the inputs */
if (image == 0 || size < 16) return 0;
/* Check the image header for the proper signature bytes */
header = (GRIP_BUF_C) image;
if (header[0] != 'D' || header[1] != 'B') return 0;
/* Extract the image offsets from the header */
img_off = ( (header[2] & 0x0F) << 12 ) |
( (header[3] & 0x0F) << 8 ) |
( (header[4] & 0x0F) << 4 ) |
( (header[5] & 0x0F) );
img_size = ( (header[6] & 0x0F) << 12 ) |
( (header[7] & 0x0F) << 8 ) |
( (header[8] & 0x0F) << 4 ) |
( (header[9] & 0x0F) );
img_check = ( (header[10] & 0x0F) << 4 ) |
( (header[11] & 0x0F) );
/* Compute the start of image core */
if ( size < ((img_off + img_size) << 4) ) return 0;
core = header + (img_off << 4);
/* Verify the checksum */
for (i = 0; i < (img_size << 4); i++) img_check ^= core[i];
if (img_check != 0) return 0;
/* Allocate memory for the core */
memory = (unsigned long) DPMI_AllocDOS(img_size, &GRIP_DS);
if (!memory) return 0;
/* Copy the image */
_dosmemputl(core, img_size << 2, memory);
/* Allocate a code selector for the core */
GRIP_CS = DPMI_AllocSel();
if (GRIP_CS == 0) {
DPMI_FreeDOS(GRIP_DS);
return 0;
}
if (DPMI_SetBounds(GRIP_CS, memory, img_size << 4) != 0) {
DPMI_FreeSel(GRIP_CS);
DPMI_FreeDOS(GRIP_DS);
return 0;
}
if (DPMI_SetCodeAR(GRIP_CS) != 0) {
DPMI_FreeSel(GRIP_CS);
DPMI_FreeDOS(GRIP_DS);
return 0;
}
/* Prepare the thunking layer */
for (i = 0; i < sizeof(GRIP_THUNK); i++)
GRIP_Thunk[i] = ((GRIP_BUF_C)core)[i];
*(GRIP_BUF_S)(GRIP_Thunk+0x02) = 0;
*(GRIP_BUF_S)(GRIP_Thunk+0x06) = GRIP_CS;
*(GRIP_BUF_S)(GRIP_Thunk+0x0C) = GRIP_CS;
/* Allocate a debugging selector if GRIP_DEBUG is defined */
#if defined(GRIP_DEBUG)
/* I don't know what this does... at least it compiles okay */
GRIP_ES = DPMI_AllocSel();
if (GRIP_ES == 0) {
DPMI_FreeSel(GRIP_CS);
DPMI_FreeDOS(GRIP_DS);
return 0;
}
if (DPMI_SetBounds(GRIP_ES, 0xB0000, 80*25*2) != 0)
{
DPMI_FreeSel(GRIP_ES);
DPMI_FreeSel(GRIP_CS);
DPMI_FreeDOS(GRIP_DS);
return 0;
}
if (DPMI_SetDataAR(GRIP_ES) != 0)
{
DPMI_FreeSel(GRIP_ES);
DPMI_FreeSel(GRIP_CS);
DPMI_FreeDOS(GRIP_DS);
return 0;
}
_farpokew(_dos_ds, memory + 0x12, 0xB000);
_farpokew(_dos_ds, memory + 0x16, GRIP_ES);
#else
_farpokew(_dos_ds, memory + 0x12, 0);
_farpokew(_dos_ds, memory + 0x16, 0);
#endif
// Save the data selector
_farpokew(_dos_ds, memory + 0x10, 0);
_farpokew(_dos_ds, memory + 0x14, GRIP_DS);
/* Complete the link */
if (Gr__Link() == 0)
{
#if defined(GRIP_DEBUG)
DPMI_FreeSel(GRIP_ES);
#endif
DPMI_FreeSel(GRIP_CS);
DPMI_FreeDOS(GRIP_DS);
return 0;
}
GRIP_Thunked = 1;
return 1;
}
