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more work on IEC, some refactoring and temporary breakage

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FeralChild64 committed 2019-06-20 11:23:30 +02:00
1 parent fd04410bd8
commit edb0013536
25 files changed
+248 -337
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c64/kernal/iec_tx_command.s
+12 -69
View File
@@ -1,63 +1,5 @@
;; XXX - TEMPORARY IMPLEMENTATION
;; https://www.pagetable.com/?p=1135, https://github.com/mist64/cbmbus_doc
;; https://www.c64-wiki.com/wiki/CIA#CIA_2
.alias CI2PRA $DD00
.alias BIT_IEC_ATN_OUT $08 ; 1 - low (pulled), 0 - high (released)
.alias BIT_IEC_CLK_OUT $10 ; 1 - low (pulled), 0 - high (released)
.alias BIT_IEC_DAT_OUT $20 ; 1 - low (pulled), 0 - high (released)
.alias BIT_IEC_CLK_IN $40 ; 0 - low (pulled), 1 - high (released)
.alias BIT_IEC_DAT_IN $80 ; 0 - low (pulled), 1 - high (released)
; XXX optimize these below
xxx_to_idle_state:
lda CI2PRA
ora #BIT_IEC_CLK_OUT ; pull
and #$FF - BIT_IEC_DAT_OUT - BIT_IEC_ATN_OUT ; release
sta CI2PRA
rts
xxx_pull_atn_clk_release_data:
lda CI2PRA
ora #BIT_IEC_ATN_OUT + BIT_IEC_CLK_OUT ; pull
and #$FF - BIT_IEC_DAT_OUT ; release
sta CI2PRA
rts
xxx_pull_clk_release_data:
lda CI2PRA
ora #BIT_IEC_CLK_OUT ; pull
and #$FF - BIT_IEC_DAT_OUT ; release
sta CI2PRA
rts
xxx_release_clk_data:
lda CI2PRA
and #$FF - BIT_IEC_CLK_OUT - BIT_IEC_DAT_OUT ; release
sta CI2PRA
rts
xxx_release_clk_pull_data:
lda CI2PRA
and #$FF - BIT_IEC_CLK_OUT ; release
ora #BIT_IEC_DAT_OUT ; pull
sta CI2PRA
rts
xxx_wait_for_data_release:
lda CI2PRA
;; Check the highest bit, which is DATA IN,
;; (highest bit set = negative value)
bpl xxx_wait_for_data_release
rts
;; Implemented based on https://www.pagetable.com/?p=1135, https://github.com/mist64/cbmbus_doc
iec_tx_command:
@@ -65,14 +7,14 @@ iec_tx_command:
;; Notify all devices that we are going to send a byte
;; and it is going to be a command (pulled ATN)
jsr xxx_pull_atn_clk_release_data
jsr iec_pull_atn_clk_release_data
;; Give devices time to respond (response is mandatory!)
jsr wait1ms
;; Did at least one device respond by pulling DATA?
lda CI2PRA
and #BIT_IEC_DAT_IN
and #BIT_CI2PRA_DAT_IN
beq +
;; No devices present on the bus, so we can immediately return with device not found
@@ -81,7 +23,7 @@ iec_tx_command:
jsr printf
.byte "DBG: NO DEVICES AT ALL", $0D, 0
jsr xxx_to_idle_state
jsr iec_set_idle
jmp kernalerror_DEVICE_NOT_FOUND
*
;; At least one device responded, but they are still allowed to stall
@@ -90,13 +32,13 @@ iec_tx_command:
;; - release back CLK, keep DATA released
;; - afterwards wait till all devices also release DATA
jsr xxx_release_clk_data
jsr xxx_wait_for_data_release
jsr iec_release_clk_data
jsr iec_wait_for_data_release
;; Pull CLK back to indicate that DATA is not valid, keep it for 60us
;; Don't wait too long, as 200us or more is considered EOI
jsr xxx_pull_clk_release_data
jsr iec_pull_clk_release_data
jsr iec_wait60us
;; Now, we can start transmission of 8 bits of data
@@ -110,11 +52,11 @@ iec_tx_command_nextbit:
bcs +
;; Bit is 0
jsr xxx_release_clk_pull_data
jsr iec_release_clk_pull_data
jmp iec_tx_command_bitset
*
;; Bit is 1
jsr xxx_release_clk_data
jsr iec_release_clk_data
iec_tx_command_bitset:
@@ -122,7 +64,7 @@ iec_tx_command_bitset:
jsr iec_wait20us
;; Pull CLK for 20us again
jsr xxx_pull_clk_release_data
jsr iec_pull_clk_release_data
jsr iec_wait20us
;; More bits to send?
@@ -145,7 +87,8 @@ iec_tx_command_bitset:
bne -
bpl iec_tx_command_done
*
;; XXX wait 100ms
;; Wait 100us to give busy devices some time
jsr iec_wait100us
iec_tx_command_done: