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open-roms/c64/basic/basic_do_new.s
T

91 lines
1.6 KiB
ArmAsm

// #LAYOUT# STD * #TAKE
// #LAYOUT# M65 * #TAKE
// #LAYOUT# X16 BASIC_0 #TAKE
// #LAYOUT# * * #IGNORE
basic_do_new:
#if (ROM_LAYOUT_M65 && SEGMENT_BASIC_0)
jsr map_BASIC_1
jsr_ind VB1__basic_do_new
jmp map_NORMAL
basic_do_clr:
jsr map_BASIC_1
jsr_ind VB1__basic_do_clr
jmp map_NORMAL
#else
// Setup pointers to memory storage XXX should depend on text start vector
lda #<$0801
sta TXTTAB+0
lda #>$0801
sta TXTTAB+1
sta VARTAB+1
lda #<$0803
sta VARTAB+0
// Zero line pointer
// XXX - We should also zero $0800, i.e., TXTTAB - 1
ldy #$00
tya
sta (TXTTAB),y
iny
sta (TXTTAB),y
// Get top of memory.
// If a cart is present, then it is $7FFF,
// if not, then it is $F7FF, since we support having
// programs and variables under ROM.
// i.e., we support 56KB RAM for BASIC, keeping some space
// free for some optimisation structures, e.g., FOR/NEXT loop
// records (without them going on the stack), GOSUB stack
// (same story), expression value cache?
sec // Read, not write value
jsr JMEMTOP
cpx #$80
beq !+
#if CONFIG_MEMORY_MODEL_60K
lda #>$F7FF
#else // CONFIG_MEMORY_MODEL_38K
lda #>$A000
#endif
.byte $2C
!:
#if CONFIG_MEMORY_MODEL_60K
lda #>$F7FF
#else // CONFIG_MEMORY_MODEL_38K
lda #>$A000
#endif
sta MEMSIZ+1
sta FRETOP+1
#if CONFIG_MEMORY_MODEL_60K
lda #<$F7FF
#else // CONFIG_MEMORY_MODEL_38K
lda #<$A000
#endif
sta MEMSIZ+0
sta FRETOP+0
// FALL THROUGH
basic_do_clr:
// Clear variables, arrays and strings
lda VARTAB+0
sta ARYTAB+0
sta STREND+0
lda VARTAB+1
sta ARYTAB+1
sta STREND+1
rts
#endif // ROM layout