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Floppy read/write speed optimizations #5

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Floppy read/write speed optimizations #5

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ef8966c
minor speed-up optimiziations
Pny May 6, 2024
cff4de9
A little bit more optimization
Pny May 6, 2024
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89 changes: 50 additions & 39 deletions src/floppy.s
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Original file line number Diff line number Diff line change
Expand Up @@ -623,8 +623,9 @@ _error_reading_sector:
rts
_copy_sector_byte_odd:
move.b (a1)+, (a0)+
move.b (a1)+, (a0)+
move.b (a1)+, (a0)+
;move.b (a1)+, (a0)+
;move.b (a1)+, (a0)+
move.w (a1)+, (a0)+
move.b (a1)+, (a0)+
dbf d4, _copy_sector_byte_odd
clr.w d0 ; Clear the error code
Expand Down Expand Up @@ -709,83 +710,73 @@ _start_async_code_in_stack:

; SEND PAYLOAD SIZE
move.l a0, d0 ; Address of the ROM3 in d0
or.w d1, d0 ; OR high and low words in d0
move.w d1, d0 ; OR high and low words in d0
move.l d0, a1 ; move to a1 ready to read from this address
move.b (a1), d0 ; Command payload size. d0 is a scratch register
tst.w d1
beq _no_more_payload_stack ; If the command does not have payload, we are done.

; SEND PAYLOAD
move.l a0, d0
or.w d2, d0
move.w d2, d0
move.l d0, a1
move.b (a1), d0 ; Command payload low d2
cmp.w #2, d1
beq _no_more_payload_stack

swap d2
move.l a0, d0
or.w d2, d0
move.w d2, d0
move.l d0, a1
move.b (a1), d0 ; Command payload high d2
cmp.w #4, d1
beq _no_more_payload_stack

move.l a0, d0
or.w d3, d0
move.w d3, d0
move.l d0, a1
move.b (a1), d0 ; Command payload low d3
cmp.w #6, d1
beq _no_more_payload_stack

swap d3
move.l a0, d0
or.w d3, d0
move.w d3, d0
move.l d0, a1
move.b (a1), d0 ; Command payload high d3
cmp.w #8, d1
beq _no_more_payload_stack

move.l a0, d0
or.w d4, d0
move.w d4, d0
move.l d0, a1
move.b (a1), d0 ; Command payload low d4
cmp.w #10, d1
beq _no_more_payload_stack

swap d4
move.l a0, d0
or.w d4, d0
move.w d4, d0
move.l d0, a1
move.b (a1), d0 ; Command payload high d4
cmp.w #12, d1
beq.s _no_more_payload_stack

move.l a0, d0
or.w d5, d0
move.w d5, d0
move.l d0, a1
move.b (a1), d0 ; Command payload low d5
cmp.w #14, d1
beq.s _no_more_payload_stack

swap d5
move.l a0, d0
or.w d5, d0
move.w d5, d0
move.l d0, a1
move.b (a1), d0 ; Command payload high d5
cmp.w #16, d1
beq.s _no_more_payload_stack

move.l a0, d0
or.w d6, d0
move.w d6, d0
move.l d0, a1
move.b (a1), d0 ; Command payload low d6
cmp.w #18, d1
beq.s _no_more_payload_stack

swap d6
move.l a0, d0
or.w d6, d0
move.w d6, d0
move.l d0, a1
move.b (a1), d0 ; Command payload high d6

Expand Down Expand Up @@ -874,30 +865,26 @@ _start_async_write_code_in_stack:

; SEND PAYLOAD SIZE
move.l a0, d0 ; Address of the ROM3 in d0
or.w d1, d0 ; OR high and low words in d0
move.w d1, d0 ; OR high and low words in d0
move.l d0, a1 ; move to a1 ready to read from this address
move.b (a1), d0 ; Command payload size. d0 is a scratch register

; SEND PAYLOAD
move.l a0, d0
or.w d2, d0
move.w d2, d0
move.l d0, a1
move.b (a1), d0 ; Command payload low d2

swap d2
move.l a0, d0
or.w d2, d0
move.w d2, d0
move.l d0, a1
move.b (a1), d0 ; Command payload high d2

move.l a0, d0
or.w d3, d0
move.w d3, d0
move.l d0, a1
move.b (a1), d0 ; Command payload low d3

swap d3
move.l a0, d0
or.w d3, d0
move.w d3, d0
move.l d0, a1
move.b (a1), d0 ; Command payload high d3

Expand All @@ -909,23 +896,47 @@ _start_async_write_code_in_stack:
btst #0, d0
beq.s _write_to_sidecart_even_loop
_write_to_sidecart_odd_loop:
move.l a0, d0
_write_to_sidecart_odd_loop2:
move.b (a4)+, d3 ; Load the high byte
lsl.w #8, d3 ; Shift it to the high part of the word
move.b (a4)+, d3 ; Load the low byte
move.l a0, d0
or.w d3, d0
move.w d3, d0
move.l d0, a1
move.b (a1), d0 ; Write the memory to the sidecart
dbf d4, _write_to_sidecart_odd_loop
dbf d4, _write_to_sidecart_odd_loop2
bra.s _write_to_sidecart_end_loop

_write_to_sidecart_even_loop:
move.w (a4)+, d3 ; Load the word
move.l a0, d0
or.w d3, d0
cmp.l #4, d6
blt _write_to_sidecart_even_loop2

move.l d6, d1 ; Use D1 as loop counter for the unrolled amount
lsr.l #2, d1 ; Divide the number of words by 4
and.l #$3, d6 ; remaining amount of words in d6
subq.l #1, d1 ; We need to copy one byte less because dbf counts 0

_write_to_sidecart_even_loop_unroll_by4: ; 4x unrolled loop
move.w (a4)+, d0 ; Load the word
move.l d0, a1
move.b (a1), d0 ; Write the memory to the sidecart
move.w (a4)+, d0 ; Load the word
move.l d0, a1
move.b (a1), d0 ; Write the memory to the sidecart
move.w (a4)+, d0 ; Load the word
move.l d0, a1
move.b (a1), d0 ; Write the memory to the sidecart
move.w (a4)+, d0 ; Load the word
move.l d0, a1
move.b (a1), d0 ; Write the memory to the sidecart
dbf d1, _write_to_sidecart_even_loop_unroll_by4

_write_to_sidecart_even_loop2:
move.w (a4)+, d0 ; Load the word
move.l d0, a1
move.b (a1), d0 ; Write the memory to the sidecart
dbf d4, _write_to_sidecart_even_loop
dbf d4, _write_to_sidecart_even_loop2

_write_to_sidecart_end_loop:
; End of the command loop. Now we need to wait for the token
Expand Down Expand Up @@ -1040,4 +1051,4 @@ countdown:
dc.b "0",8,0

even
rom_function_end:
rom_function_end: