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added MEMTOP2 pseudo kernal routine on cx16 to get the number of RAM banks

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Irmen de Jong 2021-01-05 01:48:23 +01:00
parent 3550e1214c
commit ee9f662016
2 changed files with 15 additions and 6 deletions
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13
compiler/res/prog8lib/cx16/syslib.p8
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@ -24,7 +24,7 @@ romsub $FF8D = VECTOR(uword userptr @ XY, ubyte dir @ Pc) clobbers(A,Y) ; re
romsub $FF90 = SETMSG(ubyte value @ A) ; set Kernal message control flag
romsub $FF93 = SECOND(ubyte address @ A) clobbers(A) ; (alias: LSTNSA) send secondary address after LISTEN
romsub $FF96 = TKSA(ubyte address @ A) clobbers(A) ; (alias: TALKSA) send secondary address after TALK
romsub $FF99 = MEMTOP(uword address @ XY, ubyte dir @ Pc) -> uword @ XY ; read/set top of memory pointer
romsub $FF99 = MEMTOP(uword address @ XY, ubyte dir @ Pc) -> uword @ XY ; read/set top of memory pointer. NOTE: as a Cx16 extension, also returns the number of RAM memory banks in register A ! See MEMTOP2
romsub $FF9C = MEMBOT(uword address @ XY, ubyte dir @ Pc) -> uword @ XY ; read/set bottom of memory pointer
romsub $FF9F = SCNKEY() clobbers(A,X,Y) ; scan the keyboard
romsub $FFA2 = SETTMO(ubyte timeout @ A) ; set time-out flag for IEEE bus
@ -87,6 +87,17 @@ asmsub RDTIM16() -> uword @AY {
}}
}
asmsub MEMTOP2() -> ubyte @A {
; -- uses MEMTOP's cx16 extension to query the number of available RAM banks.
%asm {{
phx
sec
jsr c64.MEMTOP
plx
rts
}}
}
}
cx16 {

8
examples/test.p8
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@ -7,12 +7,10 @@ main {
sub start () {
uword mem
ubyte num_banks
mem = 5*mem*c64.MEMTOP(0,1)
txt.print_uwhex(mem, 1)
mem = 5*mem*c64.CHRIN()
txt.print_uwhex(mem,1)
num_banks = c64.MEMTOP2()
txt.print_ub(num_banks)
test_stack.test()