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Initial attempt at emulating extended bank area access delays when 68K bus is busy with VDP stuff. Also emulate the extra delay on the second access of a word-wide read to the bank area. Needs work as it seems to break stuff.
author Michael Pavone <pavone@retrodev.com>
date Mon, 03 Feb 2014 09:18:10 -0800
parents cc6030bd04c6
children b3738ee58195
comparison
equal deleted inserted replaced
507:cc6030bd04c6 508:b976c6d6e5fb
22 movw $0, 164(%rsi) 22 movw $0, 164(%rsi)
23 call z80_save_context_scratch 23 call z80_save_context_scratch
24 pop %rax /*return address in read/write func*/ 24 pop %rax /*return address in read/write func*/
25 pop 104(%rsi) /*return address in native code*/ 25 pop 104(%rsi) /*return address in native code*/
26 sub $5, %rax /* adjust return addres to point to the call instruction that got us here */ 26 sub $5, %rax /* adjust return addres to point to the call instruction that got us here */
27 mov %rax, (%rsi)
28
29 pop %r15 /* restore callee saved regsiters */
30 pop %r14
31 pop %r13
32 pop %r12
33 pop %rbp
34 pop %rbx
35 ret /* return to caller of z80_run */
36
37 forced_sync:
38 movw $0, 164(%rsi)
39 call z80_save_context_scratch
40 pop %rax /*return address in read/write func*/
41 pop 104(%rsi) /*return address in native code*/
27 mov %rax, (%rsi) 42 mov %rax, (%rsi)
28 43
29 pop %r15 /* restore callee saved regsiters */ 44 pop %r15 /* restore callee saved regsiters */
30 pop %r14 45 pop %r14
31 pop %r13 46 pop %r13
105 z80_read_ram: 120 z80_read_ram:
106 and $0x1FFF, %r13 121 and $0x1FFF, %r13
107 mov (%r11, %r13), %r13b 122 mov (%r11, %r13), %r13b
108 ret 123 ret
109 z80_read_bank: 124 z80_read_bank:
110 /* approximation of wait states for 68K bus access */ 125 push %rsi
126 mov 144(%rsi), %rsi /* get system context pointer */
127 cmp $0, 120(%rsi) /* check bus busy flag */
128 pop %rsi
129 jne bus_busy
130 /* approximation of wait states for normal 68K bus access */
111 add $3, %ebp 131 add $3, %ebp
132 z80_read_bank_cont:
112 and $0x7FFF, %r13 133 and $0x7FFF, %r13
113 cmp $0, %r12 134 cmp $0, %r12
114 je slow_bank_read 135 je slow_bank_read
115 /* 68K memory is byte swapped */ 136 /* 68K memory is byte swapped */
116 xor $1, %r13 137 xor $1, %r13
117 mov (%r12, %r13), %r13b 138 mov (%r12, %r13), %r13b
118 ret 139 ret
119 slow_bank_read: 140 slow_bank_read:
120 /* TODO: Call into C to implement this */ 141 /* TODO: Call into C to implement this */
121 ret 142 ret
143 bus_busy:
144 mov %edi, %ebp
145 call forced_sync
146 jp z80_read_bank_cont
122 z80_read_ym2612: 147 z80_read_ym2612:
123 call z80_save_context 148 call z80_save_context
124 mov %r13w, %di 149 mov %r13w, %di
125 push %rsi 150 push %rsi
126 call z80_read_ym 151 call z80_read_ym
197 jmp z80_load_context 222 jmp z80_load_context
198 223
199 .global z80_read_word 224 .global z80_read_word
200 z80_read_word: 225 z80_read_word:
201 call z_inccycles 226 call z_inccycles
227 cmp $0x8000, %r13w
228 jae z80_read_bank_word
202 push %r13 229 push %r13
203 call z80_read_byte_noinc 230 call z80_read_byte_noinc
204 mov %r13b, %r14b 231 mov %r13b, %r14b
205 pop %r13 232 pop %r13
206 inc %r13 233 inc %r13
207 call z_inccycles 234 call z_inccycles
208 call z80_read_byte_noinc 235 call z80_read_byte_noinc
209 shl $8, %r13w 236 shl $8, %r13w
210 mov %r14b, %r13b 237 mov %r14b, %r13b
211 ret 238 ret
239
240 z80_read_bank_word:
241 push %rsi
242 mov 144(%rsi), %rsi /* get system context pointer */
243 cmp $0, 120(%rsi) /* check bus busy flag */
244 pop %rsi
245 jne bus_busy_word
246 add $3, %ebp /* first read typically has 3 wait states */
247 z80_read_bank_word_cont:
248 push %r13
249 call z80_read_bank_cont
250 mov %r13b, %r14b
251 pop %r13
252 inc %r13
253 call z_inccycles
254 push %rsi
255 mov 144(%rsi), %rsi /* get system context pointer */
256 cmp $0, 120(%rsi) /* check bus busy flag */
257 pop %rsi
258 jne bus_busy_word2
259 add $4, %ebp /* second read typically has 4 wait states */
260 z80_read_bank_word_cont2:
261 call z80_read_bank_cont
262 shl $8, %r13w
263 mov %r14b, %r13b
264 ret
265
266 bus_busy_word:
267 mov %edi, %ebp
268 call forced_sync
269 jp z80_read_bank_word_cont
270
271 bus_busy_word2:
272 mov %edi, %ebp
273 call forced_sync
274 jp z80_read_bank_word_cont2
212 275
213 .global z80_write_word_highfirst 276 .global z80_write_word_highfirst
214 z80_write_word_highfirst: 277 z80_write_word_highfirst:
215 call z_inccycles 278 call z_inccycles
216 push %r14 279 push %r14