[Snek] [keith-packard/snek] f0b0c0: lesson-3: Add bumper car source code

[Keith Packard]

  Branch: refs/heads/master
  Home:   https://github.com/keith-packard/snek
  Commit: f0b0c0739496e2402a4ecd4177fc1f22a82812a0
      https://github.com/keith-packard/snek/commit/f0b0c0739496e2402a4ecd4177fc1f22a82812a0
  Author: Keith Packard <keithp at keithp.com>
  Date:   2020-04-17 (Fri, 17 Apr 2020)

  Changed paths:
    A doc/lessons/lesson-3/bumper-car.py

  Log Message:
  -----------
  lesson-3: Add bumper car source code

Signed-off-by: Keith Packard <keithp at keithp.com>


  Commit: 65a87d4d9d165d2d9f19805b9f5bd0c094360099
      https://github.com/keith-packard/snek/commit/65a87d4d9d165d2d9f19805b9f5bd0c094360099
  Author: Keith Packard <keithp at keithp.com>
  Date:   2020-04-19 (Sun, 19 Apr 2020)

  Changed paths:
    M README.md

  Log Message:
  -----------
  Update README.md in preparation for next release

Change recent work

Signed-off-by: Keith Packard <keithp at keithp.com>


  Commit: 110bc71f654a63bb4f827e6834fcf2abb97711c1
      https://github.com/keith-packard/snek/commit/110bc71f654a63bb4f827e6834fcf2abb97711c1
  Author: Keith Packard <keithp at keithp.com>
  Date:   2020-04-20 (Mon, 20 Apr 2020)

  Changed paths:
    M snek.defs

  Log Message:
  -----------
  Add .S files to SNEK_OBJ

Signed-off-by: Keith Packard <keithp at keithp.com>


  Commit: ef2fa911d2f8808b7357efbbff9f8d99c8475208
      https://github.com/keith-packard/snek/commit/ef2fa911d2f8808b7357efbbff9f8d99c8475208
  Author: Keith Packard <keithp at keithp.com>
  Date:   2020-05-01 (Fri, 01 May 2020)

  Changed paths:
    A chips/atmega/snek-atmega-time.c
    M chips/atmega/snek-atmega.defs
    M ports/duemilanove/snek-duemilanove.c
    M ports/mega/snek-mega.c

  Log Message:
  -----------
  chips/atmega: Improve timing precision

Instead of counting something approximating milliseconds, count raw
timer over flow values and mix in the current timer value to generate
a clock at the full precision of the timer, which runs at F_CPU/64.

On a 16MHz device, this offers a resolution of 4µs.

This also shares the time code between the duemilanove and mega ports.

Reported-by: Helmut Grohne <helmut at subdivi.de>
Signed-off-by: Keith Packard <keithp at keithp.com>


  Commit: b04c3caefe1ff5f2bdbeebfc38654f5854c1fc40
      https://github.com/keith-packard/snek/commit/b04c3caefe1ff5f2bdbeebfc38654f5854c1fc40
  Author: Keith Packard <keithp at keithp.com>
  Date:   2020-05-02 (Sat, 02 May 2020)

  Changed paths:
    M chips/avr/ao-snek-avr.c

  Log Message:
  -----------
  chips/avr: Improve timing precision

Instead of counting something approximating milliseconds, count raw
timer over flow values and mix in the current timer value to generate
a clock at the full precision of the timer, which runs at F_CPU/64.

On a 16MHz device, this offers a resolution of 4µs.

Reported-by: Helmut Grohne <helmut at subdivi.de>
Signed-off-by: Keith Packard <keithp at keithp.com>


  Commit: dca0da58224591f9921b3d633681511382838a0d
      https://github.com/keith-packard/snek/commit/dca0da58224591f9921b3d633681511382838a0d
  Author: Keith Packard <keithp at keithp.com>
  Date:   2020-05-02 (Sat, 02 May 2020)

  Changed paths:
    M chips/samd21/snek-altos.c
    M chips/samd21/snek-samd21.ld

  Log Message:
  -----------
  chips/samd21: Improve timing precision

The samd21 timer code already offered ns resolution; instead of
rounding to milliseconds, use all of the available resolution for
timing.

Reported-by: Helmut Grohne <helmut at subdivi.de>
Signed-off-by: Keith Packard <keithp at keithp.com>


Compare: https://github.com/keith-packard/snek/compare/01941c19e7b1...dca0da582245