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The constructors are _NOT_ allowed anymore to access the BSS. Rather they must use the DATA segment or the INIT segment. The latter isn't cleared at any point so the constructors may use it to expose values to the main program. However they must make sure to always write the values as they are not pre-initialized.
86 lines
1.9 KiB
ArmAsm
86 lines
1.9 KiB
ArmAsm
;
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; 2014-08-22, Greg King
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;
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; int read (int fd, void* buf, unsigned count);
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;
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; This function is a hack! It lets us get text from the stdin console.
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;
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.export _read
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.constructor initstdin
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.import popax
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.importzp ptr1, ptr2, ptr3
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.forceimport disable_caps
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.macpack generic
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.include "atmos.inc"
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.proc _read
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sta ptr3
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stx ptr3+1 ; save count as result
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eor #$FF
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sta ptr2
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txa
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eor #$FF
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sta ptr2+1 ; Remember -count-1
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jsr popax ; get buf
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sta ptr1
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stx ptr1+1
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jsr popax ; get fd and discard
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L1: inc ptr2
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bnz L2
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inc ptr2+1
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bze L9 ; no more room in buf
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; If there are no more characters in BASIC's input buffer, then get a line from
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; the console into that buffer.
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L2: ldx text_count
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bpl L3
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jsr GETLINE
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ldx #<(0 - 1)
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L3: inx
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lda BASIC_BUF,x
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bnz L4 ; (zero-terminated buffer)
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ldx #<-1
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lda #$0A ; return newline char. at end of line
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L4: stx text_count
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ldy #0
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sta (ptr1),y
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inc ptr1
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bnz L1
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inc ptr1+1
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bnz L1 ; branch always
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; No error, return count.
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L9: lda ptr3
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ldx ptr3+1
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rts
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.endproc
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;--------------------------------------------------------------------------
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; initstdin: Reset the stdin console.
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.segment "ONCE"
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initstdin:
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ldx #<-1
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stx text_count
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rts
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;--------------------------------------------------------------------------
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.segment "INIT"
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text_count:
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.res 1
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