mirror of
https://github.com/irmen/prog8.git
synced 2024-12-25 23:29:55 +00:00
247 lines
6.1 KiB
Lua
247 lines
6.1 KiB
Lua
; Prog8 integer math library for 6502
|
|
; (floating point math is done via the C-64's BASIC ROM routines)
|
|
;
|
|
; some more interesting routines can be found here:
|
|
; http://6502org.wikidot.com/software-math
|
|
; http://codebase64.org/doku.php?id=base:6502_6510_maths
|
|
;
|
|
; Written by Irmen de Jong (irmen@razorvine.net) - license: GNU GPL 3.0
|
|
;
|
|
; indent format: TABS, size=8
|
|
|
|
|
|
~ math {
|
|
; note: the following ZP scratch registers must be the same as in c64lib
|
|
memory ubyte SCRATCH_ZP1 = $02 ; scratch register #1 in ZP
|
|
memory ubyte SCRATCH_ZP2 = $03 ; scratch register #2 in ZP
|
|
memory uword SCRATCH_ZPWORD1 = $fb ; scratch word in ZP ($fb/$fc)
|
|
memory uword SCRATCH_ZPWORD2 = $fd ; scratch word in ZP ($fd/$fe)
|
|
|
|
|
|
|
|
asmsub multiply_bytes (byte1: ubyte @ X, byte2: ubyte @ Y) -> clobbers(X) -> (ubyte @ A) {
|
|
; ---- multiply 2 bytes, result as byte in A (signed or unsigned)
|
|
%asm {{
|
|
stx SCRATCH_ZP1
|
|
sty SCRATCH_ZP2
|
|
ldx #8
|
|
- asl a
|
|
asl SCRATCH_ZP1
|
|
bcc +
|
|
clc
|
|
adc SCRATCH_ZP2
|
|
+ dex
|
|
bne -
|
|
rts
|
|
}}
|
|
}
|
|
|
|
|
|
asmsub multiply_bytes_16 (byte1: ubyte @ X, byte2: ubyte @ Y) -> clobbers(A) -> (uword @ XY) {
|
|
; ---- multiply 2 bytes, result as word in X/Y (unsigned)
|
|
%asm {{
|
|
lda #0
|
|
_m_with_add stx SCRATCH_ZP1
|
|
sty SCRATCH_ZP2
|
|
ldx #8
|
|
lsr SCRATCH_ZP1
|
|
- bcc +
|
|
clc
|
|
adc SCRATCH_ZP2
|
|
+ ror a
|
|
ror SCRATCH_ZP1
|
|
dex
|
|
bne -
|
|
tay
|
|
ldx SCRATCH_ZP1
|
|
rts
|
|
}}
|
|
}
|
|
|
|
asmsub multiply_bytes_addA_16 (byte1: ubyte @ X, byte2: ubyte @ Y, add: ubyte @ A) -> clobbers(A) -> (uword @ XY) {
|
|
; ---- multiply 2 bytes and add A, result as word in X/Y (unsigned)
|
|
%asm {{
|
|
jmp multiply_bytes_16._m_with_add
|
|
}}
|
|
}
|
|
|
|
word[2] multiply_words_product = 0
|
|
asmsub multiply_words (number: uword @ XY) -> clobbers(A,X) -> () {
|
|
; ---- multiply two 16-bit words into a 32-bit result
|
|
; input: X/Y = first 16-bit number, SCRATCH_ZPWORD1 in ZP = second 16-bit number
|
|
; output: multiply_words_product 32-bits product, LSB order (low-to-high)
|
|
|
|
%asm {{
|
|
stx SCRATCH_ZPWORD2
|
|
sty SCRATCH_ZPWORD2+1
|
|
|
|
mult16 lda #$00
|
|
sta multiply_words_product+2 ; clear upper bits of product
|
|
sta multiply_words_product+3
|
|
ldx #16 ; for all 16 bits...
|
|
- lsr SCRATCH_ZPWORD1+1 ; divide multiplier by 2
|
|
ror SCRATCH_ZPWORD1
|
|
bcc +
|
|
lda multiply_words_product+2 ; get upper half of product and add multiplicand
|
|
clc
|
|
adc SCRATCH_ZPWORD2
|
|
sta multiply_words_product+2
|
|
lda multiply_words_product+3
|
|
adc SCRATCH_ZPWORD2+1
|
|
+ ror a ; rotate partial product
|
|
sta multiply_words_product+3
|
|
ror multiply_words_product+2
|
|
ror multiply_words_product+1
|
|
ror multiply_words_product
|
|
dex
|
|
bne -
|
|
rts
|
|
}}
|
|
}
|
|
|
|
|
|
asmsub divmod_bytes (number: ubyte @ X, divisor: ubyte @ Y) -> clobbers() -> (ubyte @ X, ubyte @ A) {
|
|
; ---- divide X by Y, result quotient in X, remainder in A (unsigned)
|
|
; division by zero will result in quotient = 255 and remainder = original number
|
|
%asm {{
|
|
stx SCRATCH_ZP1
|
|
sty SCRATCH_ZP2
|
|
|
|
lda #0
|
|
ldx #8
|
|
asl SCRATCH_ZP1
|
|
- rol a
|
|
cmp SCRATCH_ZP2
|
|
bcc +
|
|
sbc SCRATCH_ZP2
|
|
+ rol SCRATCH_ZP1
|
|
dex
|
|
bne -
|
|
|
|
ldx SCRATCH_ZP1
|
|
rts
|
|
}}
|
|
}
|
|
|
|
asmsub divmod_words (divisor: uword @ XY) -> clobbers(A) -> (uword @ XY) {
|
|
; ---- divide two words (16 bit each) into 16 bit results
|
|
; input: SCRATCH_ZPWORD1 in ZP: 16 bit number, X/Y: 16 bit divisor
|
|
; output: SCRATCH_ZPWORD1 in ZP: 16 bit result, X/Y: 16 bit remainder
|
|
; division by zero will result in quotient = 65535 and remainder = divident
|
|
|
|
%asm {{
|
|
remainder = SCRATCH_ZP1
|
|
|
|
stx SCRATCH_ZPWORD2
|
|
sty SCRATCH_ZPWORD2+1
|
|
lda #0 ;preset remainder to 0
|
|
sta remainder
|
|
sta remainder+1
|
|
ldx #16 ;repeat for each bit: ...
|
|
|
|
- asl SCRATCH_ZPWORD1 ;number lb & hb*2, msb -> Carry
|
|
rol SCRATCH_ZPWORD1+1
|
|
rol remainder ;remainder lb & hb * 2 + msb from carry
|
|
rol remainder+1
|
|
lda remainder
|
|
sec
|
|
sbc SCRATCH_ZPWORD2 ;substract divisor to see if it fits in
|
|
tay ;lb result -> Y, for we may need it later
|
|
lda remainder+1
|
|
sbc SCRATCH_ZPWORD2+1
|
|
bcc + ;if carry=0 then divisor didn't fit in yet
|
|
|
|
sta remainder+1 ;else save substraction result as new remainder,
|
|
sty remainder
|
|
inc SCRATCH_ZPWORD1 ;and INCrement result cause divisor fit in 1 times
|
|
|
|
+ dex
|
|
bne -
|
|
|
|
lda remainder ; copy remainder to ZPWORD2 result register
|
|
sta SCRATCH_ZPWORD2
|
|
lda remainder+1
|
|
sta SCRATCH_ZPWORD2+1
|
|
|
|
ldx SCRATCH_ZPWORD1 ; load division result in X/Y
|
|
ldy SCRATCH_ZPWORD1+1
|
|
|
|
rts
|
|
|
|
}}
|
|
}
|
|
|
|
|
|
asmsub randbyte () -> clobbers() -> (ubyte @ A) {
|
|
; ---- 8-bit pseudo random number generator into A
|
|
|
|
%asm {{
|
|
lda _seed
|
|
beq +
|
|
asl a
|
|
beq ++ ;if the input was $80, skip the EOR
|
|
bcc ++
|
|
+ eor _magic ; #$1d ; could be self-modifying code to set new magic
|
|
+ sta _seed
|
|
rts
|
|
|
|
_seed .byte $3a
|
|
_magic .byte $1d
|
|
_magiceors .byte $1d, $2b, $2d, $4d, $5f, $63, $65, $69
|
|
.byte $71, $87, $8d, $a9, $c3, $cf, $e7, $f5
|
|
|
|
;returns - this comment avoids compiler warning
|
|
}}
|
|
}
|
|
|
|
asmsub randword () -> clobbers() -> (uword @ XY) {
|
|
; ---- 16 bit pseudo random number generator into XY
|
|
|
|
%asm {{
|
|
lda _seed
|
|
beq _lowZero ; $0000 and $8000 are special values to test for
|
|
|
|
; Do a normal shift
|
|
asl _seed
|
|
lda _seed+1
|
|
rol a
|
|
bcc _noEor
|
|
|
|
_doEor ; high byte is in A
|
|
eor _magic+1 ; #>magic ; could be self-modifying code to set new magic
|
|
sta _seed+1
|
|
lda _seed
|
|
eor _magic ; #<magic ; could be self-modifying code to set new magic
|
|
sta _seed
|
|
tax
|
|
ldy _seed+1
|
|
rts
|
|
|
|
_lowZero lda _seed+1
|
|
beq _doEor ; High byte is also zero, so apply the EOR
|
|
; For speed, you could store 'magic' into 'seed' directly
|
|
; instead of running the EORs
|
|
|
|
; wasn't zero, check for $8000
|
|
asl a
|
|
beq _noEor ; if $00 is left after the shift, then it was $80
|
|
bcs _doEor ; else, do the EOR based on the carry bit as usual
|
|
|
|
_noEor sta _seed+1
|
|
tay
|
|
ldx _seed
|
|
rts
|
|
|
|
|
|
_seed .word $2c9e
|
|
_magic .word $3f1d
|
|
_magiceors .word $3f1d, $3f81, $3fa5, $3fc5, $4075, $409d, $40cd, $4109
|
|
.word $413f, $414b, $4153, $4159, $4193, $4199, $41af, $41bb
|
|
|
|
;returns - this comment avoids compiler warning
|
|
}}
|
|
}
|
|
|
|
|
|
}
|