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;
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; dskctl.s -- disk made available by disk controller
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;
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;***************************************************************
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.set dskbase,0xF0400000 ; disk base address
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.set dskctrl,0 ; control register
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.set dskcnt,4 ; count register
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.set dsksct,8 ; sector register
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.set dskcap,12 ; capacity register
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.set dskbuf,0x00080000 ; disk buffer
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.set ctrlstrt,0x01 ; start bit
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.set ctrlien,0x02 ; interrupt enable bit
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.set ctrlwrt,0x04 ; write bit
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.set ctrlerr,0x08 ; error bit
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.set ctrldone,0x10 ; done bit
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.set ctrlrdy,0x20 ; ready bit
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.set sctsize,512 ; sector size in bytes
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.set retries,1000000 ; retries to get disk ready
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.export dskinit ; initialize disk
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.export dskcapctl ; determine disk capacity
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.export dskioctl ; do disk I/O
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;***************************************************************
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.code
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.align 4
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dskinit:
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jr $31
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dskcapctl:
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add $8,$0,retries ; set retry count
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add $9,$0,dskbase
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dskcap1:
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ldw $10,$9,dskctrl
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and $10,$10,ctrlrdy ; ready?
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bne $10,$0,dskcapok ; yes - jump
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sub $8,$8,1
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bne $8,$0,dskcap1 ; try again
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add $2,$0,0 ; no disk found
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j dskcapx
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dskcapok:
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ldw $2,$9,dskcap ; get disk capacity
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dskcapx:
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jr $31
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dskioctl:
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sub $29,$29,24
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stw $31,$29,20
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stw $16,$29,16
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stw $17,$29,12
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stw $18,$29,8
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stw $19,$29,4
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stw $20,$29,0
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add $16,$4,$0 ; command
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add $17,$5,$0 ; sector number
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add $18,$6,0xC0000000 ; memory address, virtualized
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add $19,$7,$0 ; number of sectors
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add $8,$0,'r'
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beq $16,$8,dskrd
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add $8,$0,'w'
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beq $16,$8,dskwr
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add $2,$0,0xFF ; illegal command
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j dskx
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dskrd:
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add $2,$0,$0 ; return ok
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beq $19,$0,dskx ; if no (more) sectors
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add $8,$0,dskbase
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add $9,$0,1
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stw $9,$8,dskcnt ; number of sectors
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stw $17,$8,dsksct ; sector number on disk
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add $9,$0,ctrlstrt
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stw $9,$8,dskctrl ; start command
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dskrd1:
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ldw $2,$8,dskctrl
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and $9,$2,ctrldone ; done?
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beq $9,$0,dskrd1 ; no - wait
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and $9,$2,ctrlerr ; error?
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bne $9,$0,dskx ; yes - leave
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add $8,$0,dskbase + dskbuf ; transfer data
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add $9,$0,sctsize
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dskrd2:
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ldw $10,$8,0 ; from disk buffer
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stw $10,$18,0 ; to memory
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add $8,$8,4
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add $18,$18,4
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sub $9,$9,4
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bne $9,$0,dskrd2
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add $17,$17,1 ; increment sector number
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sub $19,$19,1 ; decrement number of sectors
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j dskrd ; next sector
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dskwr:
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add $2,$0,$0 ; return ok
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beq $19,$0,dskx ; if no (more) sectors
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add $8,$0,dskbase + dskbuf ; transfer data
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add $9,$0,sctsize
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dskwr1:
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ldw $10,$18,0 ; from memory
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stw $10,$8,0 ; to disk buffer
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add $18,$18,4
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add $8,$8,4
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sub $9,$9,4
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bne $9,$0,dskwr1
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add $8,$0,dskbase
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add $9,$0,1
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stw $9,$8,dskcnt ; number of sectors
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stw $17,$8,dsksct ; sector number on disk
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add $9,$0,ctrlwrt | ctrlstrt
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stw $9,$8,dskctrl ; start command
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dskwr2:
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ldw $2,$8,dskctrl
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and $9,$2,ctrldone ; done?
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beq $9,$0,dskwr2 ; no - wait
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and $9,$2,ctrlerr ; error?
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bne $9,$0,dskx ; yes - leave
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add $17,$17,1 ; increment sector number
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sub $19,$19,1 ; decrement number of sectors
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j dskwr ; next sector
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dskx:
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ldw $20,$29,0
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ldw $19,$29,4
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ldw $18,$29,8
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ldw $17,$29,12
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ldw $16,$29,16
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ldw $31,$29,20
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add $29,$29,24
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jr $31
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No newline at end of file
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No newline at end of file
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