#!/bin/bash
# One HD63450 data-phase run: does the DMAC drive the SCSI data phase, and does
# it HOLD THE BUS?  (ROADMAP P4a, the last item before M2.)
#
#   tools/bench/dma_run.sh [container.dlx]
#
# The apparatus is tools/bench/scsi_run.sh's -- `x68000 -exp1 cz6bs1` and a
# zero-filled scsiexrom.bin on a private rompath -- and the volume is
# tools/bench/mkvol.sh's, the same bytes the host-file ring rig reads.
#
# WHAT A GREEN RUN MEANS: the same 2,048 B came off the disc three ways -- PIO,
# the channel with the bus held, the channel stealing cycles -- all three
# byte-exact against the host's copy; and in the held configuration THE WHOLE
# TRANSFER HAPPENED BETWEEN TWO INSTRUCTIONS, which is what holding the bus
# means and is not a claim about $EA0015 (57.3).
#
# WHAT IT DOES NOT MEAN: anything about `W`.  MAME's DMAC runs on wall-clock
# attotimes (42.5) and models a held bus by HALTING the CPU rather than by
# charging it cycles per operand.  This settles which configuration works.
set -e
cd "$(dirname "$0")/../.."
DLX=${1:-tmp/rc_fr_singe_scsi_span.dlx}

bash tools/bench/mkvol.sh "$DLX"

tools/vasm/vasmm68k_mot -Fbin -o tmp/dmagate.bin src/player/dmagate.s > /dev/null

# What the player will program, decoded out of the same constants it programs.
python3 tools/analysis/27_dmac_config.py

# stdbuf -oL: without it a long MAME run is unobservable until it exits, and a
# run that is merely finishing looks exactly like one that is wedged (34.1).
( cd tmp && SDL_VIDEODRIVER=dummy stdbuf -oL timeout -k 5 300 \
    mame x68000 -bios ipl10 -exp1 cz6bs1 \
    -rompath "$HOME/mame/roms;./p4roms" -hard dlxdisk.chd \
    -ramsize 2M -video soft -window -sound none -nothrottle -plugins \
    -autoboot_script ../tools/bench/dma.lua \
    -seconds_to_run 90 > dma_run.log 2>&1 )
grep -aq "^\[DMA\] done" tmp/dma_run.log || {
  echo "FAIL: the DMA gate did not finish -- no completion marker."
  tail -8 tmp/dma_run.log; exit 1; }
grep -a "^\[DMA\]" tmp/dma_run.log | sed 's/^\[DMA\] /  /'

# THE ASSERTIONS.  Printing a result and gating on it are different things.
fail() { echo "FAIL: $1"; exit 1; }
grep -aq "BYTES OK: 2048 B from LBA 1000 .*\[pio\]"   tmp/dma_run.log || \
  fail "the PIO reference read did not match -- nothing below is about the DMAC."
grep -aq "BYTES OK: 2048 B from LBA 1000 .*\[held\]"  tmp/dma_run.log || \
  fail "the bus-held DMA read did not deliver the disc's bytes."
grep -aq "BYTES OK: 2048 B from LBA 1000 .*\[steal\]" tmp/dma_run.log || \
  fail "the cycle-stealing DMA read did not deliver the disc's bytes."
grep -aq "MTC one instruction after START: 0 of 2048 .*NEVER EXECUTED .*\[held\]" \
  tmp/dma_run.log || \
  fail "the bus was NOT held: the CPU executed while the channel ran, so this is
      not the configuration ROADMAP P4a asks for. That MTC is the whole of the
      evidence that does not come from watching \$EA0015 (57.3)."
grep -aq "CPU trips round the wait loop: 1 \[held\]" tmp/dma_run.log || \
  fail "the held configuration's CPU went round its wait loop more than once --
      it was running, so the bus was not held for the whole transfer."
# A NEGATIVE ASSERTION IS WRITTEN AS AN `if`, not as `grep ... && fail`: under
# `set -e` a failing grep in an AND-list takes the whole script's exit status
# with it, so the run would report the failure it was looking for as a pass.
SPIN=$(sed -n 's/.*CPU trips round the wait loop: \([0-9]*\) \[steal\].*/\1/p' \
       tmp/dma_run.log)
[ -n "$SPIN" ] && [ "$SPIN" -ge 100 ] || \
  fail "the cycle-stealing configuration did not leave the CPU running (spin
      = ${SPIN:-none}) -- the two configurations are meant to DIFFER in exactly
      that, and a contrast of one against one is not a contrast."
if grep -aq "MTC one instruction after START: 0 of 2048 .*\[steal\]" tmp/dma_run.log
then
  fail "the cycle-stealing configuration also finished between two instructions,
      so the comparison has no contrast in it and the discriminator is measuring
      something other than bus ownership."
fi
grep -aq "COC .*CER=\$00 MTC=0 .*(+2048) \[held\]" tmp/dma_run.log || \
  fail "the held channel did not report a clean completion of every byte."
grep -aq "COC .*CER=\$00 MTC=0 .*(+2048) \[steal\]" tmp/dma_run.log || \
  fail "the stealing channel did not report a clean completion of every byte."
grep -aq "WINDOWED DMA READ REFUSED" tmp/dma_run.log || \
  fail "a WINDOWED read through the channel was not refused. 117 of 120 records
      start part way into a sector (58.3), and a channel cannot drop the bytes
      in front of one -- so it would write the neighbouring records into the
      ring, over data the decoder has not finished with, with no bounds check
      to catch it (49.2)."
exit 0