source: buchla-68k/orig/RAM/TIMEINT.S@ 4f508e6

Last change on this file since 4f508e6 was 3ae31e9, checked in by Thomas Lopatic <thomas@…>, 7 years ago

Imported original source code.
  • Property mode set to 100755
File size: 13.0 KB
Line 
1* ------------------------------------------------------------------------------
2* timeint.s -- MIDAS-VII timer interrupt handler
3* Version 15 -- 1989-07-20 -- D.N. Lynx Crowe
4* ------------------------------------------------------------------------------
5*
6* This code replaces the interrupt handler in bios.s, which is known to
7* have a bug in it, and adds support for the VSDD and an array of programable
8* timers with 1 Ms resolution.
9*
10* WARNING: There are equates to addresses in the bios EPROM which may change
11* when the bios is reassembled. If the bios is reassembled be sure to update
12* the equates flagged by "<<<=====".
13*
14* The addresses currently in the equates are for EPROMs dated 1988-04-18 or
15* 1988-06-20 ONLY.
16*
17* ------------------------------------------------------------------------------
18* Hardware timer usage:
19* ---------------------
20* Timer 1 PLL divider for score clock -- fixed at 64
21* Timer 2 PLL divider for score clock -- nominally 3200
22* Timer 3 1 Ms Real Time Clock
23*
24* ------------------------------------------------------------------------------
25*
26 .text
27*
28 .xdef _tsetup * tsetup() -- timer setup function
29 .xdef timeint * timer interrupt handler
30*
31 .xdef _M1IoRec * MIDI channel 1 IoRec
32 .xdef _M2IoRec * MIDI channel 2 IoRec
33 .xdef _S1IoRec * RS232 channel 1 IoRec
34 .xdef _S2IoRec * RS232 channel 2 IoRec
35 .xdef _timers * timer array -- short timers[NTIMERS]
36 .xdef _vi_clk * VSDD scroll delay timer
37 .xdef _vi_tag * VSDD VI tag
38*
39 .xref lclsadr * score object base address
40 .xref lclscrl * score object scroll offset
41 .xref _v_odtab * VSDD object descriptor table
42*
43 .page
44* ==============================================================================
45*
46FRAMES .equ 0 * set non-zero to enable frame pulses
47*
48* Equates to variables in bios.s:
49* -------------------------------
50* These variables are permanently assigned.
51*
52TIMEVEC .equ $00000400 * LONG - System timer trap vector
53*
54FC_SW .equ $00000420 * WORD - Frame clock switch
55FC_VAL .equ $00000422 * LONG - Frame clock value
56*
57HZ_1K .equ $0000049A * LONG - 1000 Hz clock
58HZ_200 .equ $0000049E * LONG - 200 Hz clock
59FRCLOCK .equ $000004A2 * LONG - 50 Hz clock
60*
61T3COUNT .equ $000004AA * WORD - Timer 3 count
62*
63* ------------------------------------------------------------------------------
64*
65* WARNING: The address of "FLOCK" depends on the version of the bios EPROM.
66* The address below is for EPROMs dated 1988-04-18 or 1988-06-20 ONLY.
67*
68FLOCK .equ $00000E0C * WORD - Floppy semaphore <<<=====
69*
70* ==============================================================================
71*
72* Equates to routines in bios.s:
73* ------------------------------
74*
75* WARNING: The address of "FLOPVBL" depends on the version of the bios EPROM.
76* The address below is for EPROMs dated 1988-04-18 or 1988-06-20 ONLY.
77*
78FLOPVBL .equ $001015EE * floppy VI handler address <<<=====
79*
80* ==============================================================================
81*
82 .page
83*
84* Hardware address equates:
85* -------------------------
86TI_VEC .equ $00000070 * Timer interrupt autovector
87*
88TIMER .equ $003A0001 * Timer base address
89M1_ACIA .equ $003AC001 * MIDI ACIA channel 1 base address
90*
91* ------------------------------------------------------------------------------
92*
93* Timer register equates:
94* -----------------------
95TIME_CRX .equ TIMER * Control register 1 or 3
96TIME_CR2 .equ TIMER+2 * Control register 2
97TIME_T1H .equ TIMER+4 * Timer 1 high byte
98TIME_T1L .equ TIMER+6 * Timer 1 low byte
99TIME_T2H .equ TIMER+8 * Timer 2 high byte
100TIME_T2L .equ TIMER+10 * Timer 2 low byte
101TIME_T3H .equ TIMER+12 * Timer 3 high byte
102TIME_T3L .equ TIMER+14 * Timer 3 low byte
103*
104* Serial I/O equates:
105* -------------------
106ACIA_CFR .equ 2 * CFR offset from ACIA base
107DTR_BIT .equ 1 * DTR bit in ACIA CFR1
108*
109IO_CFR1 .equ 29 * cfr1 offset in M1IoRec
110*
111* ==============================================================================
112*
113* Miscellaneous equates:
114* ----------------------
115IPL7 .equ $0700 * IPL mask for interrupt disable
116*
117FCMAX .equ $00FFFFFF * Maximum frame counter value
118FCMIN .equ $00000000 * Minimum frame counter value
119*
120NTIMERS .equ 8 * Number of timers in the timer array
121*
122XBIOS .equ 14 * XBIOS TRAP number
123X_PIOREC .equ 0 * X_PIOREC code
124SR1_DEV .equ 0 * RS232 ACIA channel 1
125SR2_DEV .equ 1 * RS232 ACIA channel 2
126MC1_DEV .equ 3 * MIDI ACIA channel 1
127MC2_DEV .equ 4 * MIDI ACIA channel 2
128* ==============================================================================
129*
130 .page
131* ==============================================================================
132* _tsetup -- tsetup() -- timer setup function
133* ==============================================================================
134*
135_tsetup: move.w sr,-(a7) * Save old interrupt mask
136 ori.w #IPL7,sr * Disable interrupts
137*
138 move.w #SR1_DEV,-(a7) * Establish S1IoRec
139 move.w #X_PIOREC,-(a7) * ...
140 trap #XBIOS * ...
141 add.l #4,a7 * ...
142 move.l d0,_S1IoRec * ...
143*
144 move.w #SR2_DEV,-(a7) * Establish S2IoRec
145 move.w #X_PIOREC,-(a7) * ...
146 trap #XBIOS * ...
147 add.l #4,a7 * ...
148 move.l d0,_S2IoRec * ...
149*
150 move.w #MC1_DEV,-(a7) * Establish M1IoRec
151 move.w #X_PIOREC,-(a7) * ...
152 trap #XBIOS * ...
153 add.l #4,a7 * ...
154 move.l d0,_M1IoRec * ...
155*
156 move.w #MC2_DEV,-(a7) * Establish M2IoRec
157 move.w #X_PIOREC,-(a7) * ...
158 trap #XBIOS * ...
159 add.l #4,a7 * ...
160 move.l d0,_M2IoRec * ...
161*
162 .page
163*
164 clr.w FC_SW * Stop the frame clock
165 clr.l FC_VAL * ... and reset it
166 clr.w _vi_tag * Clear VSDD VI tag
167 clr.w _vi_clk * Clear VSDD delay timer
168 clr.w lclsadr * Clear score scroll address
169 clr.w lclscrl * Clear score scroll offset
170*
171 lea _timers,a0 * Point at timer array
172 move.w #NTIMERS-1,d0 * Setup to clear timer array
173*
174tclr: clr.w (a0)+ * Clear a timer array entry
175 dbra d0,tclr * Loop until done
176*
177 move.l #nullrts,TIMEVEC * Set timer interrupt vector
178 move.l #timeint,TI_VEC * Set timer trap vector
179*
180 move.b #$00,TIME_T1H * Setup timer 1 (PLL)
181 move.b #$1F,TIME_T1L * ... for divide by 64
182 move.b #$0C,TIME_T2H * Setup timer 2 (FC)
183 move.b #$7F,TIME_T2L * ... for divide by 3200
184 move.b #$03,TIME_T3H * Setup timer 3 (RTC)
185 move.b #$20,TIME_T3L * ... for 1Ms interval
186 move.b #$42,TIME_CRX * Setup CR3
187 move.b #$41,TIME_CR2 * Setup CR2
188 move.b #$81,TIME_CRX * Setup CR1
189 move.b #$80,TIME_CRX * Start the timers
190*
191 move.w (a7)+,sr * Restore interrupts
192*
193nullrts: rts * Return to caller
194*
195 .page
196* ==============================================================================
197* timeint -- timer interrupt handler
198* ==============================================================================
199*
200timeint: movem.l d0-d7/a0-a6,-(a7) * Save registers
201 move.b TIME_CR2,d0 * Get timer interrupt status
202* ------------------------------------------------------------------------------
203* process 1 MS timer
204* ------------------------------------------------------------------------------
205 btst.l #2,d0 * Check timer 3 status
206 beq tmi02 * Jump if not active
207*
208 move.b TIME_T3H,d1 * Read timer 3 count
209 lsl.w #8,d1 * ...
210 move.b TIME_T3L,d1 * ...
211 move.w d1,T3COUNT * ... and save it
212*
213 addq.l #1,HZ_1K * Update 1ms clock (1 KHz)
214*
215 move.l d0,-(a7) * Preserve D0
216* ------------------------------------------------------------------------------
217* process VSDD timer
218* ------------------------------------------------------------------------------
219 tst.w _vi_tag * Does the VSDD need service ?
220 beq updtime * Jump if not
221*
222 move.w _vi_clk,d0 * Get VSDD scroll delay timer
223 subq.w #1,d0 * Decrement timer
224 move.w d0,_vi_clk * Update timer
225 bne updtime * Jump if it's not zero yet
226*
227 move.w lclsadr,_v_odtab+12 * Update scroll address
228 move.w lclscrl,_v_odtab+10 * Update scroll offset
229 clr.w _vi_tag * Reset the tag
230*
231 .page
232*
233* ------------------------------------------------------------------------------
234* process programable timers
235* ------------------------------------------------------------------------------
236*
237updtime: move.w #NTIMERS-1,d0 * Setup timer array counter
238 lea _timers,a0 * Point at timer array
239*
240tdcr: move.w (a0),d1 * Get timer array entry
241 beq tdcr1 * Jump if already 0
242*
243 subq.w #1,d1 * Decrement timer
244*
245tdcr1: move.w d1,(a0)+ * Store updated timer value
246 dbra d0,tdcr * Loop until done
247*
248* ------------------------------------------------------------------------------
249* process timer hook vector
250* ------------------------------------------------------------------------------
251 movea.l TIMEVEC,a0 * Get RTC vector
252 move.w #1,-(a7) * Pass 1 msec on stack
253 jsr (a0) * Process RTC vector
254 addq.l #2,a7 * Clean up stack
255*
256 move.l (a7)+,d0 * Restore D0
257*
258 .page
259* ------------------------------------------------------------------------------
260* process 5 Ms clock
261* ------------------------------------------------------------------------------
262 move.w tdiv1,d1 * Update divider
263 addq.w #1,d1 * ...
264 move.w d1,tdiv1 * ...
265*
266 cmpi.w #5,d1 * Do we need to update HZ_200 ?
267 blt tmi02 * Jump if not
268*
269 addq.l #1,HZ_200 * Update 5ms clock (200 Hz)
270* ------------------------------------------------------------------------------
271* process 20 Ms floppy clock
272* ------------------------------------------------------------------------------
273 move.w tdiv2,d1 * Update divider
274 addq.w #1,d1 * ...
275 move.w d1,tdiv2 * ...
276*
277 cmpi.w #4,d1 * Do we need to update FRCLOCK ?
278 blt tmi01 * Jump if not
279*
280 addq.l #1,FRCLOCK * Update 20 Ms clock (50 Hz)
281 tst.w FLOCK * See if floppy is active
282 bne tmi00 * Don't call FLOPVBL if so
283*
284 jsr FLOPVBL * Check on the floppy
285*
286tmi00: move.w #0,tdiv2 * Reset tdiv2
287*
288tmi01: move.w #0,tdiv1 * Reset tdiv1
289*
290 .page
291* ------------------------------------------------------------------------------
292* process PLL timers
293* ------------------------------------------------------------------------------
294*
295tmi02: btst.l #0,d0 * Check timer 1 int
296 beq tmi03 * Jump if not set
297*
298 move.b TIME_T1H,d1 * Read timer 1 to clear int.
299 move.b TIME_T1L,d1 * ...
300*
301tmi03: btst.l #1,d0 * Check for timer 2 int.
302 beq tmi04 * Jump if not set
303*
304 move.b TIME_T2H,d1 * Read timer 2 to clear int.
305 move.b TIME_T2L,d1 * ...
306*
307 .page
308* ------------------------------------------------------------------------------
309* update score frame counter
310* ------------------------------------------------------------------------------
311 tst.w FC_SW * Should we update the frame ?
312 beq tmi04 * Jump if not
313*
314 bmi tmi05 * Jump if we count down
315*
316 move.l FC_VAL,d0 * Get the frame count
317 cmp.l #FCMAX,d0 * See it we've topped out
318 bge tmi06 * Jump if limit was hit
319*
320 addq.l #1,d0 * Count up 1 frame
321 move.l d0,FC_VAL * Store updated frame count
322*
323 .ifne FRAMES
324 move.w sr,d1 * Preserve interrupt status
325 ori.w #$0700,sr * Disable interrupts
326*
327 movea.l _M1IoRec,a0 * Point at M1IoRec
328 move.b IO_CFR1(a0),d0 * Get MIDI-1 CFR1 value
329 or.b #$80,d0 * Force MSB = 1 for CFR1 output
330 movea.l #M1_ACIA,a0 * Point at MIDI-1 ACIA channel
331 bchg.l #DTR_BIT,d0 * Toggle DTR for output
332 move.b d0,ACIA_CFR(a0) * Output toggled DTR
333 bchg.l #DTR_BIT,d0 * Toggle DTR for output
334 move.b d0,ACIA_CFR(a0) * Output toggled DTR
335 move.w d1,sr * Restore interrupts
336 .endc
337*
338 bra tmi04 * Done
339*
340tmi07: move.l #FCMIN,FC_VAL * Force hard limit, just in case
341 bra tmi04 * Done
342*
343tmi06: move.l #FCMAX,FC_VAL * Force hard limit, just in case
344 bra tmi04 * Done
345*
346tmi05: move.l FC_VAL,d0 * Get the frame count
347 ble tmi07 * Done if already counted down
348*
349 subq.l #1,d0 * Count down 1 frame
350 move.l d0,FC_VAL * Store udpated frame count
351 bra tmi04 * Done
352*
353 nop * Filler to force equal paths
354*
355tmi04: movem.l (a7)+,d0-d7/a0-a6 * Restore registers
356 rte * Return to interrupted code
357*
358 .page
359* ==============================================================================
360 .bss
361* ==============================================================================
362*
363* A note on tdiv1 and tdiv2:
364* --------------------------
365*
366* tdiv1 and tdiv2 are actually defined in the bios, but since they could move
367* we define them here and ignore the ones in the bios.
368*
369tdiv1: ds.w 1 * Timer divider 1 (divides HZ_1K)
370tdiv2: ds.w 1 * Timer divider 2 (divides HZ_200)
371*
372* ------------------------------------------------------------------------------
373*
374_timers: ds.w NTIMERS * Timer array -- short timers[NTIMERS];
375*
376_vi_clk: ds.w 1 * VSDD scroll delay timer
377_vi_tag: ds.w 1 * VSDD VI 'needs service' tag
378*
379_S1IoRec: ds.l 1 * address of RS232 channel 1 IoRec
380_S2IoRec: ds.l 1 * address of RS232 channel 2 IoRec
381_M1IoRec: ds.l 1 * address of MIDI channel 1 IoRec
382_M2IoRec: ds.l 1 * address of MIDI channel 2 IoRec
383* ==============================================================================
384*
385 .end
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