ref: 4a120a381652668b7eb9313d9b8ca1835ddccb91
dir: /sys/src/9/pc/vgax.c/
#include "u.h" #include "../port/lib.h" #include "mem.h" #include "dat.h" #include "fns.h" #include "io.h" #include "../port/error.h" #define Image IMAGE #include <draw.h> #include <memdraw.h> #include <cursor.h> #include "screen.h" static Lock vgaxlock; /* access to index registers */ int vgaxi(long port, uchar index) { uchar data; ilock(&vgaxlock); switch(port){ case Seqx: case Crtx: case Grx: outb(port, index); data = inb(port+1); break; case Attrx: /* * Allow processor access to the colour * palette registers. Writes to Attrx must * be preceded by a read from Status1 to * initialise the register to point to the * index register and not the data register. * Processor access is allowed by turning * off bit 0x20. */ inb(Status1); if(index < 0x10){ outb(Attrx, index); data = inb(Attrx+1); inb(Status1); outb(Attrx, 0x20|index); } else{ outb(Attrx, 0x20|index); data = inb(Attrx+1); } break; default: iunlock(&vgaxlock); return -1; } iunlock(&vgaxlock); return data & 0xFF; } int vgaxo(long port, uchar index, uchar data) { ilock(&vgaxlock); switch(port){ case Seqx: case Crtx: case Grx: /* * We could use an outport here, but some chips * (e.g. 86C928) have trouble with that for some * registers. */ outb(port, index); outb(port+1, data); break; case Attrx: inb(Status1); if(index < 0x10){ outb(Attrx, index); outb(Attrx, data); inb(Status1); outb(Attrx, 0x20|index); } else{ outb(Attrx, 0x20|index); outb(Attrx, data); } break; default: iunlock(&vgaxlock); return -1; } iunlock(&vgaxlock); return 0; }