+++ /dev/null
-@*
-@* CPU scheduling code
-@* (C) notaz, 2007-2008
-@*
-@* This work is licensed under the terms of MAME license.
-@* See COPYING file in the top-level directory.
-@*
-
-@ SekRunPS runs PicoCpuCM68k and PicoCpuCS68k interleaved in steps of PS_STEP_M68K
-@ cycles. This is done without calling CycloneRun and jumping directly to
-@ Cyclone code to avoid pushing/popping all the registers every time.
-
-
-.equiv PS_STEP_M68K, ((488<<16)/20) @ ~24
-
-@ .extern is ignored by gas, we add these here just to see what we depend on.
-.extern CycloneJumpTab
-.extern CycloneDoInterrupt
-.extern PicoCpuCM68k
-.extern PicoCpuCS68k
-.extern SekCycleAim
-.extern SekCycleCnt
-.extern SekCycleAimS68k
-.extern SekCycleCntS68k
-
-
-.text
-.align 4
-
-
-.global SekRunPS @ cyc_m68k, cyc_s68k
-
-SekRunPS:
- stmfd sp!, {r4-r8,r10,r11,lr}
- sub sp, sp, #2*4 @ sp[0] = main_cycle_cnt, sp[4] = run_cycle_cnt
-
- @ override CycloneEnd for both contexts
- ldr r7, =PicoCpuCM68k
- ldr lr, =PicoCpuCS68k
- ldr r2, =CycloneEnd_M68k
- ldr r3, =CycloneEnd_S68k
- str r2, [r7,#0x98]
- str r3, [lr,#0x98]
-
- @ update aims
- ldr r8, =SekCycleAim
- ldr r10,=SekCycleAimS68k
- ldr r2, [r8]
- ldr r3, [r10]
- add r2, r2, r0
- add r3, r3, r1
- str r2, [r8]
- str r3, [r10]
-
- ldr r6, =CycloneJumpTab
- ldr r1, =SekCycleCnt
- ldr r0, =((488<<16)-PS_STEP_M68K)
- str r6, [r7,#0x54]
- str r6, [lr,#0x54] @ make copies to avoid literal pools
-
- @ schedule m68k for the first time..
- ldr r1, [r1]
- str r0, [sp] @ main target 'left cycle' counter
- sub r1, r2, r1
- subs r5, r1, r0, asr #16
- ble schedule_s68k @ m68k has not enough cycles
-
- str r5, [sp,#4] @ run_cycle_cnt
- b CycloneRunLocal
-
-
-
-CycloneEnd_M68k:
- ldr r3, =SekCycleCnt
- ldr r0, [sp,#4] @ run_cycle_cnt
- ldr r1, [r3]
- str r4, [r7,#0x40] ;@ Save Current PC + Memory Base
- strb r10,[r7,#0x46] ;@ Save Flags (NZCV)
- sub r0, r0, r5 @ subtract leftover cycles (which should be negative)
- add r0, r0, r1
- str r0, [r3]
-
-schedule_s68k:
- ldr r8, =SekCycleCntS68k
- ldr r10,=SekCycleAimS68k
- ldr r3, [sp]
- ldr r8, [r8]
- ldr r10,[r10]
-
- sub r0, r10, r8
- mov r2, r3
- add r3, r3, r2, asr #1
- add r3, r3, r2, asr #3 @ cycn_s68k = (cycn + cycn/2 + cycn/8)
-
- subs r5, r0, r3, asr #16
- ble schedule_m68k @ s68k has not enough cycles
-
- ldr r7, =PicoCpuCS68k
- str r5, [sp,#4] @ run_cycle_cnt
- b CycloneRunLocal
-
-
-
-CycloneEnd_S68k:
- ldr r3, =SekCycleCntS68k
- ldr r0, [sp,#4] @ run_cycle_cnt
- ldr r1, [r3]
- str r4, [r7,#0x40] ;@ Save Current PC + Memory Base
- strb r10,[r7,#0x46] ;@ Save Flags (NZCV)
- sub r0, r0, r5 @ subtract leftover cycles (should be negative)
- add r0, r0, r1
- str r0, [r3]
-
-schedule_m68k:
- ldr r1, =PS_STEP_M68K
- ldr r3, [sp] @ main_cycle_cnt
- ldr r8, =SekCycleCnt
- ldr r10,=SekCycleAim
- subs r3, r3, r1
- bmi SekRunPS_end
-
- ldr r8, [r8]
- ldr r10,[r10]
- str r3, [sp] @ update main_cycle_cnt
- sub r0, r10, r8
-
- subs r5, r0, r3, asr #16
- ble schedule_s68k @ m68k has not enough cycles
-
- ldr r7, =PicoCpuCM68k
- str r5, [sp,#4] @ run_cycle_cnt
- b CycloneRunLocal
-
-
-
-SekRunPS_end:
- ldr r7, =PicoCpuCM68k
- ldr lr, =PicoCpuCS68k
- mov r0, #0
- str r0, [r7,#0x98] @ remove CycloneEnd handler
- str r0, [lr,#0x98]
- @ return
- add sp, sp, #2*4
- ldmfd sp!, {r4-r8,r10,r11,pc}
-
-
-
-CycloneRunLocal:
- ;@ r0-3 = Temporary registers
- ldr r4,[r7,#0x40] ;@ r4 = Current PC + Memory Base
- ;@ r5 = Cycles
- ;@ r6 = Opcode Jump table
- ;@ r7 = Pointer to Cpu Context
- ;@ r8 = Current Opcode
- ldrb r10,[r7,#0x46];@ r10 = Flags (NZCV)
- ldr r1,[r7,#0x44] ;@ get SR high and IRQ level
- orr r10,r10,r10,lsl #28 ;@ r10 = Flags 0xf0000000, cpsr format
-
-;@ CheckInterrupt:
- movs r0,r1,lsr #24 ;@ Get IRQ level
- beq NoIntsLocal
- cmp r0,#6 ;@ irq>6 ?
- andle r1,r1,#7 ;@ Get interrupt mask
- cmple r0,r1 ;@ irq<=6: Is irq<=mask ?
- bgt CycloneDoInterrupt
-NoIntsLocal:
-
-;@ Check if our processor is in special state
-;@ and jump to opcode handler if not
- ldr r0,[r7,#0x58] ;@ state_flags
- ldrh r8,[r4],#2 ;@ Fetch first opcode
- tst r0,#0x03 ;@ special state?
- andeq r10,r10,#0xf0000000
- ldreq pc,[r6,r8,asl #2] ;@ Jump to opcode handler
-
-CycloneSpecial2:
- tst r0,#2 ;@ tracing?
- bne CycloneDoTrace
-;@ stopped or halted
- sub r4,r4,#2
- ldr r1,[r7,#0x98]
- mov r5,#0
- bx r1
-
-@ vim:filetype=armasm
notaz.gp2x.de / picodrive.git / commitdiff