Files
open-roms/c64/basic/basic_insert_line.s
T

106 lines
2.0 KiB
ArmAsm

#if ROM_LAYOUT_STD || (ROM_LAYOUT_M65 && SEGMENT_BASIC_0)
// Insert the tokenised line stored at $0200.
// First work out where in the list to put it
// (basic_find_line with the line number can be used to work
// out the insertion point, as it should abort once it finds a
// line number too high).
// Then all we have to do is push the rest of the BASIC text up,
// and update the pointers in all following basic lines.
basic_insert_line:
// ASSUMES basic_find_line has been called to set the insert point.
// We need to insert space for the link link token, the line number,
// and the zero-terminated line itself. This means 2+2+1 plus length
// of tokenised string after the line number
// But first, remember where the pointer will be, so that we can
// put the line in there after.
// jsr printf
// .text "INSERTING LINE AT $"
// .byte $f1,<OLDTXT,>OLDTXT
// .byte $f0,<OLDTXT,>OLDTXT
// .byte $0d,0
lda OLDTXT+0
pha
lda OLDTXT+1
pha
// Get number of bytes in tokenised line after line number
lda __tokenise_work2
sec
sbc __tokenise_work1
// Add on the four bytes space we need
clc
adc #5
pha
tax
// Make the space
jsr basic_shift_mem_up_and_relink
// Now increase top of BASIC mem
pla
clc
adc VARTAB+0
sta VARTAB+0
lda VARTAB+1
adc #0
sta VARTAB+1
// Get pointer back
pla
sta OLDTXT+1
pla
sta OLDTXT+0
// Write the line number
ldy #2
lda LINNUM+0
#if CONFIG_MEMORY_MODEL_60K
ldx #<OLDTXT+0
jsr poke_under_roms
#else // CONFIG_MEMORY_MODEL_38K
sta (OLDTXT),y
#endif
iny
lda LINNUM+1
#if CONFIG_MEMORY_MODEL_60K
jsr poke_under_roms
#else // CONFIG_MEMORY_MODEL_38K
sta (OLDTXT),y
#endif
// Now store the line body itself
inc __tokenise_work2
line_store_loop:
ldx __tokenise_work1
lda $0200,x
inc __tokenise_work1
iny
#if CONFIG_MEMORY_MODEL_60K
ldx #<OLDTXT+0
jsr poke_under_roms
#else // CONFIG_MEMORY_MODEL_38K
sta (OLDTXT),y
#endif
lda __tokenise_work1
cmp __tokenise_work2
bne line_store_loop
dec __tokenise_work2
clc
rts
#endif // ROM layout