VORTEX_SRCBLOCK_SR
hwwrite(vortex->mmio, VORTEX_SRCBLOCK_SR,
hwread(vortex->mmio, VORTEX_SRCBLOCK_SR) | (0x1 << channel));
hwwrite(vortex->mmio, VORTEX_SRCBLOCK_SR,
hwread(vortex->mmio, VORTEX_SRCBLOCK_SR) & ~(0x1 << channel));
temp = hwread(vortex->mmio, VORTEX_SRCBLOCK_SR);
eax = hwread(vortex->mmio, VORTEX_SRCBLOCK_SR);