Two benefits:
1) We don't accumulate errors from the delay between the timer reset and
the deadline preceding it
2) In the future, we may use WAIT to wait for timer expiration, which
should cause less bus activity and is should also reduce jitter
- regs4740.h (TFR. TFSR, TFCR, TDHR): added more timer registers
- ubb-vga.c (until): renamed to "delay" and changed to measure relative
to the last deadline
- ubb-vga.c (line, hdelay, frame): replaced "until" with "delay"
- ubb-vga.c (hdelay, frame, session): reset the timer only once, at
the beginning of the session
- ubb-vga.c (frame): we didn't wait for the horizontal back porch of
the last image line
- regs4740.h (REG_PADDR): translate a register access to the
corresponding physical address
- regs4740.h (REG_WINDOW): added register window size
- regs4740.h (CGU, INT, TCU, GPIO, MSC): prefix register group macros
with an underscore, to avoid name collision with DMAC
- regs4740.h: added DMAC registers
- regs4740.h (MSC_NOP): should be MSC_NOB
- regs4740.h: macros to access selected Jz4740 registers
- ubb-vga2.c: replaced all pointers to registers with access macros
- ubb-vga2.c (line_cycles): we now seem to be 0.1 us slower
