48 lines
1.3 KiB
ArmAsm
48 lines
1.3 KiB
ArmAsm
;; #LAYOUT# STD * #TAKE
|
|
;; #LAYOUT# X16 BASIC_0 #TAKE-OFFSET 2000
|
|
;; #LAYOUT# * BASIC_0 #TAKE
|
|
;; #LAYOUT# * * #IGNORE
|
|
|
|
; This file is under the MIT license, it contains code released by Microsoft Corporation.
|
|
; See LICENSE for more information.
|
|
|
|
; Math package - add exponents of FAC1 and FAC2 for multiplication and division
|
|
;
|
|
; This is verified to be identical to the original Microsoft implementation where it was named MULDIV
|
|
;
|
|
|
|
|
|
;CHECK SPECIAL CASES AND ADD EXPONENTS FOR FMULT, FDIV.
|
|
|
|
MULDIV:
|
|
lda FAC2_exponent ; Exponent of FAC2 = 0?
|
|
MLDEXP:
|
|
beq ZEREMV
|
|
clc
|
|
adc FAC1_exponent ; Result is in A
|
|
bcc @1 ; Find CF XOR NF
|
|
bmi GOOVER ; Overflow if bits match
|
|
clc
|
|
+skip_2_bytes_trash_nvz
|
|
@1:
|
|
bpl ZEREMV ; underflow
|
|
adc #$80 ; Add bias
|
|
sta FAC1_exponent
|
|
bne @2
|
|
jmp ZEROML ; Zero the rest of it
|
|
@2:
|
|
lda ARISGN
|
|
sta FAC1_sign ; ARISGN is result's sign
|
|
rts
|
|
|
|
MLDVEX:
|
|
lda FAC1_sign
|
|
eor #$FF
|
|
bmi GOOVER
|
|
ZEREMV:
|
|
pla ; Get address off stack
|
|
pla
|
|
jmp zero_FAC1 ; underflow
|
|
GOOVER:
|
|
jmp overflow_error ; overflow
|