Update normal_FAC1
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Rikard Nordgren authored and FeralChild64 committed
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@@ -211,8 +211,8 @@ Floating point mathematical routines - not official, but well known and broadly
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| `$B867` | `add_MEM_FAC1` | DONE | From the Microsoft BASIC, original name: FADD |
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| `$B86A` | `add_FAC2_FAC1` | DONE | |
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| `$B8D2` | `abs_and_normal_FAC` | DONE | From the Microsoft BASIC, original name: FADFLT |
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| `$B8D7` | `normal_FAC1` | DONE | From the Microsoft BASIC, original name: NORMAL |
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| `$B8F7` | `zero_FAC1` | DONE | From the Microsoft BASIC, original name: ZEROFC |
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| `$B8FE` | `normal_FAC1` | DONE | |
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| `$B947` | `inv_FAC1_mantissa` | DONE | From the Microsoft BASIC, original name: NEGFAC |
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| `$B96F` | `inc_FAC1` | DONE | From the Microsoft BASIC, original name: INCFAC |
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| `$B983` | `shiftr_FAC1` | DONE | From the Microsoft BASIC, original name: SHIFTR |
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@@ -0,0 +1,41 @@
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;; #LAYOUT# STD * #TAKE
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;; #LAYOUT# X16 BASIC_0 #TAKE-OFFSET 2000
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;; #LAYOUT# * BASIC_0 #TAKE
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;; #LAYOUT# * * #IGNORE
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; This file is under the MIT license, it contains code released by Microsoft Corporation.
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; See LICENSE for more information.
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; Math package - normalize FAC1
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;
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; This is verified to be identical to the original Microsoft implementation where it was named NORMAL.
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;
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; See also:
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; - [CM64] Computes Mapping the Commodore 64 - page 113
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; - https://www.c64-wiki.com/wiki/Floating_point_arithmetic
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; - https://codebase64.org/doku.php?id=base:kernal_floating_point_mathematics
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;
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normal_FAC1:
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ldy #0
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tya
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clc
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@1:
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ldx FAC1_mantissa+0
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bne NORM1
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ldx FAC1_mantissa+1 ; Shift 8 bites at a time for speed
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stx FAC1_mantissa
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ldx FAC1_mantissa+2
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stx FAC1_mantissa+1
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ldx FAC1_mantissa+3
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stx FAC1_mantissa+2
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ldx FACOV
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stx FAC1_mantissa+3
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sty FACOV
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adc #8
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cmp #$20
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bne @1
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; Fallthrough to zero_FAC1
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@@ -1,101 +0,0 @@
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;; #LAYOUT# STD * #TAKE
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;; #LAYOUT# * BASIC_0 #TAKE
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;; #LAYOUT# * * #IGNORE
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;
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; Math package - normalize FAC1
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;
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; See also:
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; - [CM64] Computes Mapping the Commodore 64 - page 113
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; - https://www.c64-wiki.com/wiki/Floating_point_arithmetic
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; - https://codebase64.org/doku.php?id=base:kernal_floating_point_mathematics
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;
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; XXX test this
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normal_FAC1_impl:
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lda FAC1_exponent
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beq normal_FAC1_end ; branch if our float is 0
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; FALLTROUGH
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normal_FAC1_check_mantissa_byte:
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lda FAC1_mantissa+0
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beq normal_FAC1_by_byte ; branch if we can move the whole byte
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; FALLTROUGH
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normal_FAC1_check_mantissa_bit:
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lda FAC1_mantissa+0 ; XXX optimize for 65CE02?
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and #$80
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bne normal_FAC1_end ; branch if already normalized
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; FALLTROUGH
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normal_FAC1_by_bit:
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; Decrement the exponent
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dec FAC1_exponent
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beq normal_FAC1_end ; exponent reached 0, nothing more to do
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; Multiply the mantissa by 2
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asl FACOV
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rol FAC1_mantissa+3
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rol FAC1_mantissa+2
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rol FAC1_mantissa+1
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rol FAC1_mantissa+0
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bcc normal_FAC1_check_mantissa_bit ; branch if next iteration needed
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rts
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normal_FAC1_by_byte:
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; First decrement the exponent by 8, but not below 0
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lda FAC1_exponent
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sec
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sbc #$08
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bcs @1
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lda #$00
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@1:
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sta FAC1_exponent
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beq normal_FAC1_end ; branch if our float reached 0
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; Now multiply the mantissa by 8 by moving the whole bytes
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lda FAC1_mantissa+1
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sta FAC1_mantissa+0
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lda FAC1_mantissa+2
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sta FAC1_mantissa+1
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lda FAC1_mantissa+3
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sta FAC1_mantissa+2
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lda FACOV
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sta FAC1_mantissa+3
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lda #$00
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sta FACOV
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; Now check if mantissa is not 0
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ora FAC1_mantissa+0
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ora FAC1_mantissa+1
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ora FAC1_mantissa+2
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ora FAC1_mantissa+3
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bne normal_FAC1_check_mantissa_byte ; not 0 - branch to next iteration
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; Our mantissa reached 0 - mark exponent as 0 and finish
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sta FAC1_exponent
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; FALLTROUGH
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normal_FAC1_end:
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rts
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+2
-3
@@ -20,14 +20,13 @@ int matches[MAX_SIZE];
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int phase_mask[MAX_SIZE+MAX_SIZE];
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#define NUM_CHUNKS 10
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#define NUM_CHUNKS 9
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// Pairs of start, end memory addresses of known exact similarity with the open source Microsoft BASIC
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unsigned short microsoft_basic_chunks[NUM_CHUNKS * 2] = {
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0xB391, 0xB39D,
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0xB3A2, 0xB3A5,
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0xB849, 0xB869,
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0xB8D2, 0xB8D5,
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0xB8F7, 0xB8FD,
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0xB8D2, 0xB8FD,
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0xB947, 0xB97D,
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0xB983, 0xB9BB,
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0xBA8C, 0xBAB6,
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