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https://github.com/RaySollium99/picodrive.git
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149 lines
3.3 KiB
ArmAsm
149 lines
3.3 KiB
ArmAsm
/*
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* PicoDrive
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* (C) notaz, 2009
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*
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* This work is licensed under the terms of MAME license.
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* See COPYING file in the top-level directory.
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*/
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.equ M68K_MEM_SHIFT, 16
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.global cyclone_checkpc
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.global cyclone_fetch8
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.global cyclone_fetch16
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.global cyclone_fetch32
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.global cyclone_read8
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.global cyclone_read16
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.global cyclone_read32
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.global cyclone_write8
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.global cyclone_write16
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.global cyclone_write32
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@ Warning: here we abuse the fact that we are only called
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@ from Cyclone, and assume that r7 contains context pointer.
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cyclone_checkpc:
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ldr r1, [r7, #0x60] @ membase
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sub r0, r0, r1
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and r3, r0, #0xff000000
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bic r0, r0, #1
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bics r2, r0, #0xff000000
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beq crashed
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ldr r1, [r7, #0x6c] @ read16 map
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mov r2, r2, lsr #M68K_MEM_SHIFT
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ldr r1, [r1, r2, lsl #2]
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movs r1, r1, lsl #1
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bcs crashed
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sub r1, r1, r3
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str r1, [r7, #0x60] @ membase
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add r0, r0, r1
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bx lr
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crashed:
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stmfd sp!,{lr}
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mov r1, r7
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bl cyclone_crashed
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ldr r0, [r7, #0x40] @ reload PC + membase
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ldmfd sp!,{pc}
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cyclone_read8: @ u32 a
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cyclone_fetch8:
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bic r0, r0, #0xff000000
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ldr r1, [r7, #0x68] @ read8 map
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mov r2, r0, lsr #M68K_MEM_SHIFT
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ldr r1, [r1, r2, lsl #2]
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eor r2, r0, #1
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movs r1, r1, lsl #1
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ldrccb r0, [r1, r2]
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bxcc lr
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bx r1
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cyclone_read16: @ u32 a
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cyclone_fetch16:
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bic r0, r0, #0xff000000
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ldr r1, [r7, #0x6c] @ read16 map
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mov r2, r0, lsr #M68K_MEM_SHIFT
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ldr r1, [r1, r2, lsl #2]
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bic r0, r0, #1
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movs r1, r1, lsl #1
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ldrcch r0, [r1, r0]
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bxcc lr
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bx r1
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cyclone_read32: @ u32 a
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cyclone_fetch32:
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bic r0, r0, #0xff000000
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ldr r1, [r7, #0x6c] @ read16 map
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mov r2, r0, lsr #M68K_MEM_SHIFT
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ldr r1, [r1, r2, lsl #2]
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bic r0, r0, #1
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movs r1, r1, lsl #1
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ldrcch r0, [r1, r0]!
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ldrcch r1, [r1, #2]
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orrcc r0, r1, r0, lsl #16
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bxcc lr
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stmfd sp!,{r0,r1,r2,lr}
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mov lr, pc
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bx r1
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mov r2, r0, lsl #16
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ldmfd sp!, {r0,r1}
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str r2, [sp]
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add r0, r0, #2
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mov lr, pc
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bx r1
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ldmfd sp!, {r1,lr}
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mov r0, r0, lsl #16
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orr r0, r1, r0, lsr #16
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bx lr
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cyclone_write8: @ u32 a, u8 d
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bic r0, r0, #0xff000000
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ldr r2, [r7, #0x74] @ write8 map
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mov r3, r0, lsr #M68K_MEM_SHIFT
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ldr r2, [r2, r3, lsl #2]
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eor r3, r0, #1
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movs r2, r2, lsl #1
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strccb r1, [r2, r3]
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bxcc lr
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bx r2
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cyclone_write16: @ u32 a, u16 d
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bic r0, r0, #0xff000000
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ldr r2, [r7, #0x78] @ write16 map
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mov r3, r0, lsr #M68K_MEM_SHIFT
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ldr r2, [r2, r3, lsl #2]
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bic r0, r0, #1
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movs r2, r2, lsl #1
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strcch r1, [r2, r0]
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bxcc lr
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bx r2
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cyclone_write32: @ u32 a, u32 d
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bic r0, r0, #0xff000000
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ldr r2, [r7, #0x78] @ write16 map
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mov r3, r0, lsr #M68K_MEM_SHIFT
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ldr r2, [r2, r3, lsl #2]
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bic r0, r0, #1
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movs r2, r2, lsl #1
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movcc r3, r1, lsr #16
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strcch r3, [r2, r0]!
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strcch r1, [r2, #2]
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bxcc lr
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stmfd sp!,{r0-r2,lr}
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mov r1, r1, lsr #16
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mov lr, pc
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bx r2
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ldmfd sp!,{r0-r2,lr}
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add r0, r0, #2
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bx r2
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@ vim:filetype=armasm
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