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1 | * H316 SAFE SOFTWARE STACK, REV. 0.1 |
2 | * |
3 | * |
4 | * AUTHOR: |
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5 | * |
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6 | * PHILIPP HACHTMANN, 2007 |
7 | * |
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8 | * VERSIONS: |
9 | * |
10 | * 0.1 - INITIAL REVISION (22.12.2007) |
11 | * |
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12 | * PURPOSE: |
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13 | * |
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14 | * TO PROVIDE A MULTI-PURPOSE STACK MECHANISM |
15 | * TO PROVIDE A SPECIAL-PURPOSE STACK MECHANISM FOR RECURSIVE |
16 | * PROGRAM CALLS |
17 | * |
18 | * WHAT: |
19 | * |
20 | * THIS VARIANT OF THE STACK ROUTINE USES A FIXED SIZE MEMORY |
21 | * BUFFER FOR THE THE STACK. THE STACK USAGE IS MONITORED. |
22 | * ON OVERFLOW, THE COMPUTER TYPES OUT AN ERROR MESSAGE AND HALTS. |
23 | * |
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24 | * |
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25 | * USAGE: |
26 | * |
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27 | * INITIALISING STACK POINTER: |
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28 | * |
29 | * CALL S$INIT |
30 | * |
31 | * PUSHING AND POPPING THE A-REGISTER FROM AND TO THE STACK: |
32 | * |
33 | * CALL S$PUSH VALUE IN A REGISTER IS PUSHED. |
34 | * CALL $$PUSH VALUE FROM STACK IS POPPED INTO A-REGISTER. |
35 | * |
36 | * PUSHING AND POPPING ARBITRARY DATA FROM AND TO THE STACK: |
37 | * |
38 | * CALL S$PUSM |
39 | * DAC ADDRESS |
40 | * OCT SIZE |
41 | * |
42 | * CALL S$POPM |
43 | * DAC ADDRESS |
44 | * OCT SIZE |
45 | * |
46 | * |
47 | ******************************************************************************** |
48 | * |
49 | * |
50 | **** SYMBOL DECLARATIONS |
51 | * |
52 | SUBR STACK,SBUF JUST A LABEL FOR THE OBJECT TAPE |
53 | SUBR S$INIT,INIT INITITALISATION |
54 | SUBR S$PUSH,PUSH SINGLE WORD PUSH |
55 | SUBR S$POP,POP SINGLE WORD POP |
56 | SUBR S$PUSM,PUSM MEMORY RANGE PUSH |
57 | SUBR S$POPM,POPM MEMORY RANGE POP |
58 | SUBR S$PTR,SPTR STACK POINTER ACCESS |
59 | * |
60 | * |
61 | ******************************************************************************** |
62 | * |
63 | * |
64 | SSIZ EQU '1000 512 WORDS DEFAULT STACK BUFFER SIZE |
65 | * |
66 | REL RELOCATEABLE OBJECT |
67 | ORG '0 |
68 | * |
69 | * |
70 | ******************************************************************************** |
71 | * |
72 | * |
73 | **** PUSH MEMORY RANGE TO STACK |
74 | * |
75 | PUSM DAC ** ENTRY POINT TO PUSH ROUTINE |
76 | STA ATM1 SAVE A-REGISTER |
77 | * |
78 | LDA* PUSM LOAD POINTER |
79 | STA PTR STORE TO TRANSFER POINTER |
80 | IRS PUSM GO TO NEXT ARGUMENT |
81 | LDA* PUSM LOAD TRANSFER SIZE |
82 | IRS PUSM CORRECT RETURN ADDRESS |
83 | * |
84 | TCA NEGATE WORD COUNT |
85 | STA CNT STORE TO COUNTER |
86 | * |
87 | PULP LDA* PTR GET DATA |
88 | JST PUSH PUSH IT! |
89 | IRS PTR INCREMENT POINTER |
90 | IRS CNT INCREMENT BYTE COUNTER |
91 | JMP PULP DO IT AGAIN! |
92 | * |
93 | LDA ATM1 RESTORE A-REG |
94 | JMP* PUSM |
95 | * |
96 | * |
97 | ******************************************************************************** |
98 | * |
99 | * |
100 | **** POP MEMORY RANGE FROM STACK |
101 | * |
102 | POPM DAC ** ENTRY POINT TO PUSH ROUTINE |
103 | STA ATM1 SAVE A-REGISTER |
104 | * |
105 | LDA* POPM LOAD POINTER |
106 | IRS POPM GO TO NEXT ARGUMENT |
107 | ADD* POPM ADD TRANSFER SIZE |
108 | SUB =1 SUBSTRACT 1 TO GET HIGH ADDRESS |
109 | STA PTR STORE TO TRANSFER POINTER |
110 | LDA* POPM LOAD TRANSFER SIZE |
111 | IRS POPM CORRECT RETURN ADDRESS |
112 | * |
113 | TCA NEGATE WORD COUNT |
114 | STA CNT STORE TO COUNTER |
115 | * |
116 | POLP JST POP POP DATA FROM THE STACK |
117 | STA* PTR STORE IT. |
118 | LDA PTR |
119 | SUB =1 DECREMENT |
120 | STA PTR WRITE BACK |
121 | IRS CNT INCREMENT BYTE COUNTER |
122 | JMP POLP DO IT AGAIN! |
123 | * |
124 | LDA ATM1 |
125 | JMP* POPM |
126 | * |
127 | * |
128 | ******************************************************************************** |
129 | * |
130 | * |
131 | **** PUSH SINGLE WORD ONTO STACK |
132 | * |
133 | PUSH DAC ** REAL PUSH ROUTINE - PUSH AC TO STACK. |
134 | * |
135 | STA ATM2 SAVE A REGISTER |
136 | * |
137 | LDA SPTR LOAD STACK POINTER |
138 | SUB MAX TEST IF STACK FULL |
139 | SNZ |
140 | JST OFLO OVERFLOW OH! OH! OH! |
141 | * |
142 | LDA ATM2 |
143 | STA* SPTR NO OVERFLOW, PUT DATA ONTO STACK |
144 | IRS SPTR INCREMENT STACK POINTER |
145 | * |
146 | JMP* PUSH RETURN WITH A-REG UNALTERED. |
147 | * |
148 | * |
149 | ******************************************************************************** |
150 | * |
151 | * |
152 | **** POP SINGLE WORD FROM STACK |
153 | * |
154 | POP DAC ** REAL POP ROUTINE - POP AC FROM STACK. |
155 | * |
156 | LDA SPTR LOAD STACK POINTER |
157 | SUB MIN TEST IF STACK EMPTY |
158 | SNZ |
159 | JST UFLO UNDERFLOW OH! OH! OH! |
160 | * |
161 | LDA SPTR LOAD STACK POINTER |
162 | SUB =1 DECREMENT IT TO LAST USED LOCATION |
163 | STA SPTR SAVE IT BACK |
164 | * |
165 | LDA* SPTR LOAD VALUE FROM THE STACK |
166 | JMP* POP RETURN. |
167 | * |
168 | * |
169 | ******************************************************************************** |
170 | * |
171 | * |
172 | **** INITIALIZATION |
173 | * |
174 | INIT DAC ** INITIALIZE STACK POINTER |
175 | LDA CPTR LOAD INITIAL STACK POINTER |
176 | STA SPTR SET STACK POINTER |
177 | JMP* INIT |
178 | * |
179 | * |
180 | ******************************************************************************** |
181 | * |
182 | * |
183 | **** ERROR HANDLING ROUTINES |
184 | * |
185 | OFLO DAC ** STACK OVERFLOW ROUTINE |
186 | LDA OMSP LOAD OVERFLOW MESSAGE POINTER |
187 | JST TYPE TYPE IT OUT. |
188 | * |
189 | HLT WHAT WE DO: HALT THE MACHINE. |
190 | JMP *-1 YOU CANNOT SIMPLY LEAVE THIS, IT'S SERIOUS! |
191 | * |
192 | * |
193 | **************************************** |
194 | * |
195 | * |
196 | UFLO DAC ** STACK OVERFLOW ROUTINE |
197 | LDA UMSP LOAD OVERFLOW MESSAGE POINTER |
198 | JST TYPE TYPE IT OUT. |
199 | * |
200 | HLT WHAT WE DO: HALT THE MACHINE. |
201 | JMP *-1 YOU CANNOT SIMPLY LEAVE THIS, IT'S SERIOUS! |
202 | * |
203 | * |
204 | **************************************** |
205 | * |
206 | * |
207 | TYPE DAC ** |
208 | SKS '104 TEST ASR READY |
209 | JMP *-1 WAIT TO BECOME READY |
210 | OCP '104 SET TO OUTPUT MODE |
211 | * |
212 | STA PTR STORE POINTER |
213 | * |
214 | TLOP LDA* PTR TYPE LOOP |
215 | SNZ TEST FOR END |
216 | JMP* TYPE RETURN |
217 | ICA |
218 | OTA '4 |
219 | JMP *-1 |
220 | ICA |
221 | OTA '4 |
222 | JMP *-1 |
223 | SKS '104 ADDITIONAL TEST FOR READY |
224 | JMP *-1 |
225 | IRS PTR NEXT WORD. |
226 | JMP TLOP |
227 | * |
228 | * |
229 | ******************************************************************************** |
230 | * |
231 | * |
232 | ***** VARIABLES |
233 | * |
234 | SBUF BSS SSIZ THE STACK BUFFER |
235 | SPTR DAC SBUF THE STACK POINTER |
236 | * |
237 | PTR DEC 0 TRANSFER POINTER TO USER BUFFERS |
238 | CNT DEC 0 TRANSFER COUNTER |
239 | * |
240 | ATM1 DEC 0 A-REGISTER BACKUP |
241 | ATM2 DEC 0 A-REGISTER BACKUP |
242 | * |
243 | * |
244 | ***** CONSTANTS |
245 | * |
246 | CPTR DAC SBUF STACK POINTER CONSTANT |
247 | MAX DAC SBUF+SSIZ FIRST ILLEGAL SPTR LOC BEFORE PUSH |
248 | MIN DAC SBUF FIRST ILLEGAL SPTR LOC BEFORE POP |
249 | * |
250 | OMSP DAC OMSG POINTER TO MESSAGE |
251 | UMSP DAC UMSG POINTER TO MESSAGE |
252 | OMSG OCT '006412 CR/LF CHARACTERS |
253 | BCI 16,STACK OVERFLOW, YOUR'RE SCREWED! |
254 | DEC 0 TERMINATION CHARACTER |
255 | UMSG OCT '006412 CR/LF CHARACTERS |
256 | BCI 17,STACK UNDERFLOW, YOUR'RE SCREWED! |
257 | DEC 0 TERMINATION CHARACTER |
258 | * |
259 | * |
260 | ******************************************************************************** |
261 | * |
262 | * |
263 | END THAT'S IT. |