Cyclone interface for new mem system, minor tweaks

[picodrive.git] / pico / m68kif_cyclone.s

diff --git a/pico/m68kif_cyclone.s b/pico/m68kif_cyclone.s
new file mode 100644 (file)
index 0000000..ea5daa6
--- /dev/null
+++ b/pico/m68kif_cyclone.s
@@ -0,0 +1,140 @@
+@ vim:filetype=armasm
+
+.equ M68K_MEM_SHIFT, 16
+
+.global cyclone_checkpc
+.global cyclone_fetch8
+.global cyclone_fetch16
+.global cyclone_fetch32
+.global cyclone_read8
+.global cyclone_read16
+.global cyclone_read32
+.global cyclone_write8
+.global cyclone_write16
+.global cyclone_write32
+
+@ Warning: here we abuse the fact that we are only called
+@ from Cyclone, and assume that r7 contains context pointer.
+cyclone_checkpc:
+    ldr     r1, [r7, #0x60]  @ membase
+    sub     r0, r0, r1
+    bic     r0, r0, #0xff000000
+    bics    r0, r0, #1
+    beq     crashed
+
+    ldr     r1, [r7, #0x6c]  @ read16 map
+    mov     r2, r0, lsr #M68K_MEM_SHIFT
+    ldr     r1, [r1, r2, lsl #2]
+    movs    r1, r1, lsl #1
+    bcs     crashed
+
+    str     r1, [r7, #0x60]  @ membase
+    add     r0, r0, r1
+    bx      lr
+
+crashed:
+    stmfd   sp!,{lr}
+    mov     r1, r7
+    bl      cyclone_crashed
+    ldr     r0, [r7, #0x40]  @ reload PC + membase
+    ldmfd   sp!,{pc}
+
+
+cyclone_read8: @ u32 a
+cyclone_fetch8:
+    bic     r0, r0, #0xff000000
+    ldr     r1, [r7, #0x68]  @ read8 map
+    mov     r2, r0, lsr #M68K_MEM_SHIFT
+    ldr     r1, [r1, r2, lsl #2]
+    eor     r2, r0, #1
+    movs    r1, r1, lsl #1
+    ldrccb  r0, [r1, r2]
+    bxcc    lr
+    bx      r1
+
+
+cyclone_read16: @ u32 a
+cyclone_fetch16:
+    bic     r0, r0, #0xff000000
+    ldr     r1, [r7, #0x6c]  @ read16 map
+    mov     r2, r0, lsr #M68K_MEM_SHIFT
+    ldr     r1, [r1, r2, lsl #2]
+    bic     r0, r0, #1
+    movs    r1, r1, lsl #1
+    ldrcch  r0, [r1, r0]
+    bxcc    lr
+    bx      r1
+
+
+cyclone_read32: @ u32 a
+cyclone_fetch32:
+    bic     r0, r0, #0xff000000
+    ldr     r1, [r7, #0x6c]  @ read16 map
+    mov     r2, r0, lsr #M68K_MEM_SHIFT
+    ldr     r1, [r1, r2, lsl #2]
+    bic     r0, r0, #1
+    movs    r1, r1, lsl #1
+    ldrcch  r0, [r1, r0]!
+    ldrcch  r1, [r1, #2]
+    orrcc   r0, r1, r0, lsl #16
+    bxcc    lr
+
+    stmfd   sp!,{r0,r1,lr}
+    mov     lr, pc
+    bx      r1
+    mov     r2, r0, lsl #16
+    ldmia   sp, {r0,r1}
+    str     r2, [sp]
+    add     r0, r0, #2
+    mov     lr, pc
+    bx      r1
+    ldr     r1, [sp]
+    mov     r0, r0, lsl #16
+    orr     r0, r1, r0, lsr #16
+    ldmfd   sp!,{r1,r2,pc}
+
+
+cyclone_write8: @ u32 a, u8 d
+    bic     r0, r0, #0xff000000
+    ldr     r2, [r7, #0x74]  @ write8 map
+    mov     r3, r0, lsr #M68K_MEM_SHIFT
+    ldr     r2, [r2, r3, lsl #2]
+    eor     r3, r0, #1
+    movs    r2, r2, lsl #1
+    strccb  r1, [r2, r3]
+    bxcc    lr
+    bx      r2
+
+
+cyclone_write16: @ u32 a, u16 d
+    bic     r0, r0, #0xff000000
+    ldr     r2, [r7, #0x78]  @ write16 map
+    mov     r3, r0, lsr #M68K_MEM_SHIFT
+    ldr     r2, [r2, r3, lsl #2]
+    bic     r0, r0, #1
+    movs    r2, r2, lsl #1
+    strcch  r1, [r2, r0]
+    bxcc    lr
+    bx      r2
+
+
+cyclone_write32: @ u32 a, u32 d
+    bic     r0, r0, #0xff000000
+    ldr     r2, [r7, #0x78]  @ write16 map
+    mov     r3, r0, lsr #M68K_MEM_SHIFT
+    ldr     r2, [r2, r3, lsl #2]
+    bic     r0, r0, #1
+    movs    r2, r2, lsl #1
+    movcc   r3, r1, lsr #16
+    strcch  r3, [r2, r0]!
+    strcch  r1, [r2, #2]
+    bxcc    lr
+
+    stmfd   sp!,{r0-r2,lr}
+    mov     r1, r1, lsr #16
+    mov     lr, pc
+    bx      r2
+    ldmfd   sp!,{r0-r2,lr}
+    add     r0, r0, #2
+    bx      r2
+