dac write index register is r/w (Volker Ruppert)

git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@977 c046a42c-6fe2-441c-8c8c-71466251a162

hw/vga.c

@@ -190,6 +190,9 @@ static uint32_t vga_ioport_read(void *opaque, uint32_t addr)
         case 0x3c7:
             val = s->dac_state;
             break;
+	case 0x3c8:
+	    val = s->dac_write_index;
+	    break;
         case 0x3c9:
             val = s->palette[s->dac_read_index * 3 + s->dac_sub_index];
             if (++s->dac_sub_index == 3) {