diff --git a/libsrc/atmos/read.s b/libsrc/atmos/read.s
index 83aa8024e..3f22d8d0e 100644
--- a/libsrc/atmos/read.s
+++ b/libsrc/atmos/read.s
@@ -20,18 +20,19 @@
sta ptr3
stx ptr3+1 ; save count as result
- eor #$FF
- sta ptr2
- txa
- eor #$FF
- sta ptr2+1 ; Remember -count-1
+
+ inx
+ stx ptr2+1
+ tax
+ inx
+ stx ptr2 ; save count with each byte incremented separately
jsr popptr1 ; get buf
jsr popax ; get fd and discard
-L1: inc ptr2
+L1: dec ptr2
bnz L2
- inc ptr2+1
+ dec ptr2+1
bze L9 ; no more room in buf
; If there are no more characters in BASIC's input buffer, then get a line from
diff --git a/libsrc/atmos/write.s b/libsrc/atmos/write.s
index 7865b5698..4a68994ec 100644
--- a/libsrc/atmos/write.s
+++ b/libsrc/atmos/write.s
@@ -17,17 +17,17 @@
sta ptr3
stx ptr3+1 ; save count as result
- eor #$FF
- sta ptr2
- txa
- eor #$FF
- sta ptr2+1 ; Remember -count-1
+ inx
+ stx ptr2+1
+ tax
+ inx
+ stx ptr2 ; save count with each byte incremented separately
jsr popptr1 ; get buf
jsr popax ; get fd and discard
-L1: inc ptr2
+L1: dec ptr2
bne L2
- inc ptr2+1
+ dec ptr2+1
beq L9
L2: ldy #0
lda (ptr1),y
diff --git a/libsrc/cbm/read.s b/libsrc/cbm/read.s
index ee01596aa..fb0bb3171 100644
--- a/libsrc/cbm/read.s
+++ b/libsrc/cbm/read.s
@@ -106,9 +106,9 @@
; Decrement the count
-@L3: inc ptr2
+@L3: dec ptr2
bne @L0
- inc ptr2+1
+ dec ptr2+1
bne @L0
beq done ; Branch always
diff --git a/libsrc/cbm/rwcommon.s b/libsrc/cbm/rwcommon.s
index a1f92be8c..d13c478b5 100644
--- a/libsrc/cbm/rwcommon.s
+++ b/libsrc/cbm/rwcommon.s
@@ -21,11 +21,11 @@
.proc rwcommon
- eor #$FF
- sta ptr2
- txa
- eor #$FF
- sta ptr2+1 ; Remember -count-1
+ inx
+ stx ptr2+1
+ tax
+ inx
+ stx ptr2 ; Save count with each byte incremented separately
jsr popptr1 ; Get buf to ptr1, Y=0 by call
diff --git a/libsrc/cbm/write.s b/libsrc/cbm/write.s
index 7a27f0044..ebc44a0ac 100644
--- a/libsrc/cbm/write.s
+++ b/libsrc/cbm/write.s
@@ -83,9 +83,9 @@
; Decrement count
-@L2: inc ptr2
+@L2: dec ptr2
bne @L0
- inc ptr2+1
+ dec ptr2+1
bne @L0
; Wrote all chars or disk full. Close the output channel
diff --git a/libsrc/common/memcmp.s b/libsrc/common/memcmp.s
index 93a2c28dc..5879a433d 100644
--- a/libsrc/common/memcmp.s
+++ b/libsrc/common/memcmp.s
@@ -13,11 +13,11 @@ _memcmp:
; Calculate (-count-1) and store it into ptr3. This is some overhead here but
; saves time in the compare loop
- eor #$FF
- sta ptr3
- txa
- eor #$FF
- sta ptr3+1
+ inx
+ stx ptr3+1
+ tax
+ inx
+ stx ptr3 ; Save count with each byte incremented separately
; Get the pointer parameters
@@ -33,7 +33,7 @@ _memcmp:
; Head of compare loop: Test for the end condition
-Loop: inx ; Bump low byte of (-count-1)
+Loop: dex ; Bump low byte of (-count-1)
beq BumpHiCnt ; Jump on overflow
; Do the compare
@@ -53,7 +53,7 @@ Comp: lda (ptr1),y
; Entry on low counter byte overflow
BumpHiCnt:
- inc ptr3+1 ; Bump high byte of (-count-1)
+ dec ptr3+1 ; Bump high byte of (-count-1)
bne Comp ; Jump if not done
jmp return0 ; Count is zero, areas are identical
@@ -67,4 +67,3 @@ NotEqual:
Greater:
ldx #$01 ; Make result positive
rts
-
diff --git a/libsrc/common/strncat.s b/libsrc/common/strncat.s
index caa6804fc..060378442 100644
--- a/libsrc/common/strncat.s
+++ b/libsrc/common/strncat.s
@@ -5,17 +5,17 @@
; char* strncat (char* dest, const char* src, size_t n);
;
- .export _strncat
- .import popax, popptr1
- .importzp ptr1, ptr2, ptr3, tmp1, tmp2
- .macpack cpu
+.export _strncat
+.import popax, popptr1
+.importzp ptr1, ptr2, ptr3, tmp1, tmp2
+.macpack cpu
_strncat:
- eor #$FF ; one's complement to count upwards
- sta tmp1
- txa
- eor #$FF
- sta tmp2
+ inx
+ stx tmp2
+ tax
+ inx
+ stx tmp1 ; save count with each byte incremented separately
jsr popptr1 ; get src
@@ -49,9 +49,9 @@ L2: sty ptr2
L3: ldy #0
ldx tmp1 ; low counter byte
-L4: inx
+L4: dex
bne L5
- inc tmp2
+ dec tmp2
beq L6 ; jump if done
L5: lda (ptr1),y
sta (ptr2),y
diff --git a/libsrc/common/strncpy.s b/libsrc/common/strncpy.s
index 56387f880..49bd90b32 100644
--- a/libsrc/common/strncpy.s
+++ b/libsrc/common/strncpy.s
@@ -10,11 +10,11 @@
.proc _strncpy
- eor #$FF
- sta tmp1
- txa
- eor #$FF
- sta tmp2 ; Store -size - 1
+ inx
+ stx tmp2
+ tax
+ inx
+ stx tmp1 ; save count with each byte incremented separately
jsr popptr1 ; get src
jsr popax ; get dest
@@ -26,9 +26,9 @@
ldx tmp1 ; Load low byte of ones complement of size
ldy #$00
-L1: inx
+L1: dex
bne L2
- inc tmp2
+ dec tmp2
beq L9
L2: lda (ptr1),y ; Copy one character
@@ -42,7 +42,7 @@ L2: lda (ptr1),y ; Copy one character
; Fill the remaining bytes.
-L3: inx ; Counter low byte
+L3: dex ; Counter low byte
beq L6 ; Branch on overflow
L4: sta (ptr2),y ; Clear one byte
L5: iny ; Bump pointer
@@ -52,7 +52,7 @@ L5: iny ; Bump pointer
; Bump the counter high byte
-L6: inc tmp2
+L6: dec tmp2
bne L4
; Done, return dest
diff --git a/libsrc/common/strnicmp.s b/libsrc/common/strnicmp.s
index 43d6d0d50..f447b9683 100644
--- a/libsrc/common/strnicmp.s
+++ b/libsrc/common/strnicmp.s
@@ -15,17 +15,11 @@
_strnicmp:
_strncasecmp:
-; Convert the given counter value in a/x from a downward counter into an
-; upward counter, so we can increment the counter in the loop below instead
-; of decrementing it. This adds some overhead now, but is cheaper than
-; executing a more complex test in each iteration of the loop. We do also
-; correct the value by one, so we can do the test on top of the loop.
-
- eor #$FF
- sta ptr3
- txa
- eor #$FF
- sta ptr3+1
+ inx
+ stx ptr3+1
+ tax
+ inx
+ stx ptr3 ; save count with each byte incremented separately
; Get the remaining arguments
@@ -40,7 +34,7 @@ _strncasecmp:
; Start of compare loop. Check the counter.
-Loop: inc ptr3
+Loop: dec ptr3
beq IncHi ; increment high byte
; Compare a byte from the strings
@@ -79,7 +73,7 @@ L2: ldx tmp1
; Increment hi byte
-IncHi: inc ptr3+1
+IncHi: dec ptr3+1
bne Comp ; jump if counter not zero
; Exit code if strings are equal. a/x not set
diff --git a/libsrc/conio/vcprintf.s b/libsrc/conio/vcprintf.s
index 3a9ddf9d7..084efe089 100644
--- a/libsrc/conio/vcprintf.s
+++ b/libsrc/conio/vcprintf.s
@@ -47,12 +47,12 @@ outdesc: ; Static outdesc structure
out: jsr popax ; count
sta ptr2
- eor #$FF
- sta outdesc+6
- txa
- sta ptr2+1
- eor #$FF
- sta outdesc+7
+ stx ptr2+1
+ inx
+ stx outdesc+7
+ tax
+ inx
+ stx outdesc+6
jsr popptr1 ; buf
@@ -74,7 +74,7 @@ out: jsr popax ; count
; Loop outputting characters
-@L1: inc outdesc+6
+@L1: dec outdesc+6
beq @L4
@L2: ldy tmp1
lda (ptr1),y
@@ -85,7 +85,7 @@ out: jsr popax ; count
jsr _cputc
jmp @L1
-@L4: inc outdesc+7
+@L4: dec outdesc+7
bne @L2
rts
diff --git a/libsrc/geos-common/drivers/fio_module.s b/libsrc/geos-common/drivers/fio_module.s
index 0be5015a7..937ef292e 100644
--- a/libsrc/geos-common/drivers/fio_module.s
+++ b/libsrc/geos-common/drivers/fio_module.s
@@ -94,11 +94,12 @@ _read:
; popax - fd, must be == to the above one
; return -1+__oserror or number of bytes read
- eor #$ff
- sta ptr1
- txa
- eor #$ff
- sta ptr1+1 ; -(# of bytes to read)-1
+ inx
+ stx ptr1+1
+ tax
+ inx
+ stx ptr1 ; save count with each byte incremented separately
+
jsr popax
sta ptr2
stx ptr2+1 ; buffer ptr
@@ -152,9 +153,9 @@ _read:
beq @done ; yes, we're done
jmp __mappederrno ; no, we're screwed
-@L3: inc ptr1 ; decrement the count
+@L3: dec ptr1 ; decrement the count
bne @L0
- inc ptr1+1
+ dec ptr1+1
bne @L0
@done:
diff --git a/libsrc/osic1p/bootstrap.s b/libsrc/osic1p/bootstrap.s
index ed2ade222..efb480cb8 100644
--- a/libsrc/osic1p/bootstrap.s
+++ b/libsrc/osic1p/bootstrap.s
@@ -50,16 +50,17 @@ LINEDIST = $20 ; Offset in video RAM between two lines
ldx #>load_addr
sta load
stx load+1
- lda #<load_size
- eor #$FF
- sta count ; store (-size - 1)
- lda #>load_size
- eor #$FF
- sta count+1
-L1: inc count ; pre-count one's-complement upwards
+ ldx #<load_size
+ inx
+ stx count
+ ldx #>load_size
+ inx
+ stx count+1 ; save size with each byte incremented separately
+
+L1: dec count ; pre-count one's-complement upwards
bnz L2
- inc count+1
+ dec count+1
bze L3
L2: jsr GETCHAR ; (doesn't change .Y)
sta (load),y
diff --git a/libsrc/telestrat/write.s b/libsrc/telestrat/write.s
index 68aef42d6..215db3e52 100644
--- a/libsrc/telestrat/write.s
+++ b/libsrc/telestrat/write.s
@@ -13,11 +13,11 @@
sta ptr3
stx ptr3+1 ; save count as result
- eor #$FF
- sta ptr2
- txa
- eor #$FF
- sta ptr2+1 ; remember -count-1
+ inx
+ stx ptr2+1
+ tax
+ inx
+ stx ptr2 ; save count with each byte incremented separately
jsr popptr1 ; get buf
jsr popax ; get fd and discard
@@ -51,9 +51,9 @@ next:
rts
-L1: inc ptr2
+L1: dec ptr2
bne L2
- inc ptr2+1
+ dec ptr2+1
beq L9
L2: ldy #0
lda (ptr1),y