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Use state machine for stepper motor changes

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This commit is contained in:
Peter Evans 2018-03-02 16:42:22 -06:00
parent cbf693b186
commit 998a139c00
2 changed files with 45 additions and 61 deletions
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87
src/apple2.dd.c
View File

@ -14,6 +14,30 @@
#include "apple2.enc.h"
#include "apple2.h"
// This is a small sort of state machine, which I adapted from AppleInPC
// (https://github.com/sosaria7/appleinpc) because I could not honestly
// think of a cleaner way of representing the step transitions that are
// possible. All credit to that project.
static int stepper_fsm[][8] =
{
{ 0, 0, 0, 0, 0, 0, 0, 0 }, // 0000
{ 0, -1, -2, -3, 0, 3, 2, 1 }, // 1000
{ 2, 1, 0, -1, -2, -3, 0, 3 }, // 0100
{ 1, 0, -1, -2, -3, 0, 3, 2 }, // 1100
{ 0, 3, 2, 1, 0, -1, -2, -3 }, // 0010
{ 0, -1, 0, 1, 0, -1, 0, 1 }, // 1010
{ 3, 2, 1, 0, -1, -2, -3, 0 }, // 0110
{ 2, 1, 0, -1, -2, -3, 0, 3 }, // 1110
{ -2, -3, 0, 3, 2, 1, 0, -1 }, // 0001
{ -1, -2, -3, 0, 3, 2, 1, 0 }, // 1001
{ 0, 1, 0, -1, 0, 1, 0, -1 }, // 0101
{ 0, -1, -2, -3, 0, 3, 2, 1 }, // 1101
{ -3, 0, 3, 2, 1, 0, -1, -2 }, // 0011
{ -2, -3, 0, 3, 2, 1, 0, -1 }, // 1011
{ 0, 3, 2, 1, 0, -1, -2, -3 }, // 0111
{ 0, 0, 0, 0, 0, 0, 0, 0 } // 1111
};
/*
* Create a new disk drive. We do not create a memory segment for the
* drive right away, as the size of said data can be variable based on
@ -235,62 +259,15 @@ apple2_dd_phaser(apple2dd *drive)
{
int phase = drive->phase_state;
int last = drive->last_phase;
int step = 0;
if (phase == (last << 1)) {
step++;
} else if (phase == 0x1 && last == 0x8) {
step++;
} else if (phase == (last >> 1)) {
step--;
} else if (phase == 0x8 && last == 0x1) {
step--;
}
if (phase == 0 && last == 0) {
step = 0;
}
if (phase == 1 && last == 0) {
step = 1;
}
#if 0
// This is a bit of trickery; there is no phase state for 0x10 or
// 0x0, but we want to pretend like the phase is "next" to the bit
// we're operating with for the purpose of establishing a direction.
if (phase == 0x1 && last == 0x8) {
phase = 0x10;
} else if (phase == 0x8 && last == 0x1) {
phase = 0x0;
}
// We only want to respond to adjacent phases, so if the last phase
// shifted in _any_ direction is not equal to the phase state, then
// we should do nothing.
if (phase != 0 && (phase << 1) != last && (phase >> 1) != last) {
if (!drive->online) {
return;
}
// The above check works for non-zero phases, but for zero phases,
// the logic is a bit different.
if (phase == 0 && last != 0x1 && last != 0x8) {
return;
}
#endif
apple2_dd_step(drive, step);
#if 0
// If phase > last, then we must move the head forward by a half
// track. If it's < last, then we move the head backward, again by a
// half track.
if (phase > last) {
apple2_dd_step(drive, 1);
} else if (phase < last) {
apple2_dd_step(drive, -1);
}
#endif
// Look up the number of steps to move according to the current
// phase and the current track position.
apple2_dd_step(drive,
stepper_fsm[phase][drive->track_pos & 0x7]);
// Recall our trickery above with the phase variable? Because of it,
// we have to save the phase_state field into last_phase, and not
@ -421,6 +398,12 @@ apple2_dd_step(apple2dd *drive, int steps)
} else if (drive->track_pos < 0) {
drive->track_pos = 0;
}
// The sector position is rehomed to zero whenever we step a
// non-zero length.
if (steps) {
drive->sector_pos = 0;
}
}
/*

19
tests/apple2.dd.c
View File

@ -203,24 +203,25 @@ Test(apple2_dd, decode)
Test(apple2_dd, phaser)
{
// Test going backwards
drive->track_pos = 3;
drive->phase_state = 1;
drive->last_phase = 0;
drive->online = true;
apple2_dd_phaser(drive);
cr_assert_eq(drive->track_pos, 1);
cr_assert_eq(drive->track_pos, 0);
cr_assert_eq(drive->last_phase, 1);
// This shouldn't work--we should stay at the track_pos we begin
// with
drive->phase_state = 0x4;
// Forwards
drive->phase_state = 9;
drive->track_pos = 5;
drive->last_phase = 8;
apple2_dd_phaser(drive);
cr_assert_eq(drive->track_pos, 1);
// And test that we can go backward
drive->phase_state = 0x2;
apple2_dd_phaser(drive);
cr_assert_eq(drive->track_pos, 0);
cr_assert_eq(drive->track_pos, 7);
cr_assert_eq(drive->last_phase, 9);
}
Test(apple2_dd, switch_phase)