1993/0915/pc/dma.c (diff list | history)

1992/1013/sys/src/9/pc/dma.c:33,39 – 1993/0915/sys/src/9/pc/dma.c:33,39 (short | long | prev | next)
1991/0803		*/ struct DMAxfer { Page *pg; /* page used by dma */
1993/0915		Page pg; /* page used by dma */
1991/0803		void *va; /* virtual address destination/src */ long len; /* bytes to be transferred */ int isread;
1992/1013/sys/src/9/pc/dma.c:79,84 – 1993/0915/sys/src/9/pc/dma.c:79,105
1991/0803		}; /*
1993/0915		* DMA must be in the first 16 meg. This gets called early by main() to * ensure that. */ void dmainit(void) { int i, chan; DMA *dp; DMAxfer *xp; for(i = 0; i < 2; i++){ dp = &dma[i]; for(chan = 0; chan < 4; chan++){ xp = &dp->x[chan]; xp->pg.pa = (ulong)xspanalloc(BY2PG, BY2PG, 0); xp->pg.va = KZERO|xp->pg.pa; } } } /*
1991/0803		* setup a dma transfer. if the destination is not in kernel * memory, allocate a page for the transfer. *
1992/1013/sys/src/9/pc/dma.c:101,122 – 1993/0915/sys/src/9/pc/dma.c:122,142
1991/0803		xp = &dp->x[chan]; /* * if this isn't kernel memory (or crossing 64k boundary), * allocate a page for the DMA.
1993/0915		* if this isn't kernel memory or crossing 64k boundary or above 16 meg * use the allocated low memory page.
1991/0803		*/ pa = ((ulong)va) & ~KZERO;
1993/0915		pa = PADDR(va);
1992/1013		if((((ulong)va)&0xF0000000) != KZERO || (pa&0xFFFF0000) != ((pa+len)&0xFFFF0000)){
1991/0925		if(xp->pg == 0) xp->pg = newpage(1, 0, 0);
1993/0915		|| (pa&0xFFFF0000) != ((pa+len)&0xFFFF0000) || pa > 16*MB){
1991/0803		if(len > BY2PG) len = BY2PG; if(!isread) memmove((void*)(KZERO|xp->pg->pa), va, len);
1993/0915		memmove((void*)(xp->pg.va), va, len);
1991/0803		xp->va = va; xp->len = len; xp->isread = isread; pa = xp->pg->pa;
1993/0915		pa = xp->pg.pa;
1991/0925		} else xp->len = 0;
1991/0803
1992/1013/sys/src/9/pc/dma.c:168,173 – 1993/0915/sys/src/9/pc/dma.c:188,193
1991/0803		/* * copy out of temporary page */ memmove(xp->va, (void*)(KZERO|xp->pg->pa), xp->len);
1993/0915		memmove(xp->va, (void*)(xp->pg.va), xp->len);
1991/0925		xp->len = 0;
1991/0803		}