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#include <stdio.h>
#include <stdlib.h>
#include <dos.h>


void far *aligned_malloc(long len)
{
	void far *ptr;
	unsigned int far *orig_ptr;
	unsigned seg, orig_seg, orig_off;
	long lin_addr;

	/* Allocate double the required space */

	if(allocmem((len * 2L + 32L + 15L) >> 4, &seg) != -1)
		return NULL;

	/* Compute a new pointer to the buffer such that the next "len" bytes */
	/* do not cross a page boundary, and the offset is zero */
	/* (as required by DMA transfers) */
	orig_off = 0;
	orig_seg = seg;
	/* reserve 4 bytes for the original pointer */
	lin_addr = (orig_seg * 16L) + orig_off + 4L;
	if((lin_addr & 0xF0000L) != ((lin_addr+len-1) & 0xF0000L))
		lin_addr = (lin_addr+len-1)&0xF0000L;
	else
		lin_addr = (lin_addr+15) & 0xFFFF0L;

	seg = (unsigned int)(lin_addr/16);
	orig_ptr = (unsigned far *)MK_FP(seg-1,0x000C);
	orig_ptr[0] = orig_off;
	orig_ptr[1] = orig_seg;
	ptr = MK_FP(seg, 0);

/*
	printf("Original: %04x:%04x, New: %04x:%04x, Linear: %05lx\n",
	orig_seg,orig_off,FP_SEG(ptr),FP_OFF(ptr),lin_addr);
*/

	return ptr;
}


void aligned_free(void far *ptr)
{
	if(ptr!=NULL) {
		unsigned far *old_ptr=(unsigned far *)MK_FP(FP_SEG(ptr)-1,0x000c);
      /*
	 printf("Freeing: %04x:%04x, Ptr: %04x:%04x\n",
	 FP_SEG(old_ptr),FP_OFF(old_ptr),FP_SEG(ptr),FP_OFF(ptr));
	 */
		farfree(MK_FP(old_ptr[1],old_ptr[0]));
	}
}
.

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