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implemented MOVFM math routine

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FeralChild64 committed 2020-01-29 21:12:01 +01:00
1 parent 0e319d9871
commit 35712baca7
10 files changed
+38 -61
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STATUS.md
+2 -2
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@@ -186,12 +186,12 @@ Floating point mathematical routines - not official, but well known and broadly
| `$B9EA` | `LOG` | NOT DONE | XXX - no stub added yet |
| `$BA28` | `FMUL` | PARTIAL | needs `FMULT` |
| `$BA2B` | `FMULT` | NOT DONE | multiplies FAC1 by FAC2 |
| `$BA8C` | `CONUPK` | PARTIAL | not tested yet |
| `$BA8C` | `CONUPK` | PARTIAL | not fully tested yet |
| `$BAE2` | `MUL10` | NOT DONE | multiply FAC1 by 10 |
| `$BAFE` | `DIV10` | NOT DONE | divide FAC1 by 10, result is always positive |
| `$BB0F` | `FDIV` | PARTIAL | needs `FDIVT` |
| `$BB12` | `FDIVT` | NOT DONE | divide FAC2 by FAC1, ignores sign |
| `$BBA2` | `MOVFM` | NOT DONE | fetch FAC1 from RAM location |
| `$BBA2` | `MOVFM` | PARTIAL | not fully tested yet |
| `$BBD4` | `MOVMF` | NOT DONE | copy FAC1 to memory location, rounds if asked |
| `$BBFC` | `MOVEF` | NOT DONE | copy FAC2 to FAC1 |
| `$BC0F` | `MOVFA` | NOT DONE | copy FAC1 to FAC2, skips rounding |
c64/basic/,stubs_math/b853.FSUBT.s
+1 -1
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@@ -9,7 +9,7 @@
// - .A - must load FAC1 exponent ($61) beforehand to set the zero flag
//
// Note:
// - load FAC2 after FAC1, or mimic the Kernals sign comparison
// - load FAC2 after FAC1, or mimic the Kernals sign comparison (XXX do we need it?)
//
// See also:
// - [CM64] Computes Mapping the Commodore 64 - page 112
c64/basic/,stubs_math/b86a.FADDT.s
+1 -1
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@@ -9,7 +9,7 @@
// - .A - must load FAC1 exponent ($61) beforehand to set the zero flag
//
// Note:
// - load FAC2 after FAC1, or mimic the Kernals sign comparison
// - load FAC2 after FAC1, or mimic the Kernals sign comparison (XXX do we need it?)
//
// See also:
// - [CM64] Computes Mapping the Commodore 64 - page 112
c64/basic/,stubs_math/ba2b.FMULT.s
+1 -1
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@@ -9,7 +9,7 @@
// - .A - must load FAC1 exponent ($61) beforehand to set the zero flag
//
// Note:
// - load FAC2 after FAC1, or mimic the Kernals sign comparison
// - load FAC2 after FAC1, or mimic the Kernals sign comparison (XXX do we need it?)
//
// See also:
// - [CM64] Computes Mapping the Commodore 64 - page 113 XXX address does not match
c64/basic/,stubs_math/bba2.MOVFM.s
-25
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@@ -1,25 +0,0 @@
// #LAYOUT# STD * #TAKE
// #LAYOUT# * BASIC_0 #TAKE
// #LAYOUT# * * #IGNORE
//
// Math package - copy FAC1 to memory location, rounds if asked
//
// Input:
// - .X - address low byte
// - .Y - address high byte
// - $70 - if MSB is set performs rouding
//
// Output:
// - .A - FAC1 exponent
//
// See also:
// - [CM64] Computes Mapping the Commodore 64 - page 114
// - https://www.c64-wiki.com/wiki/Floating_point_arithmetic
// - https://codebase64.org/doku.php?id=base:kernal_floating_point_mathematics
//
// XXX provide implementation
MOVMF:
STUB_IMPLEMENTATION()
c64/basic/,stubs_math/bbd4.MOVMF.s
+5 -4
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@@ -3,17 +3,18 @@
// #LAYOUT# * * #IGNORE
//
// Math package - fetch FAC1 from RAM location
// Math package - copy FAC1 to memory location, rounds if asked
//
// Input:
// - .A - address low byte
// - .X - address low byte
// - .Y - address high byte
// - $70 - if MSB is set performs rouding
//
// Output:
// - .A - FAC1 exponent, affects status flags
// - .Y - always 0
// - .A - FAC1 exponent
//
// See also:
// - [CM64] Computes Mapping the Commodore 64 - page 114
// - https://www.c64-wiki.com/wiki/Floating_point_arithmetic
// - https://codebase64.org/doku.php?id=base:kernal_floating_point_mathematics
//
c64/basic/,stubs_math/bf7b.FPWRT.s
+1 -1
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@@ -9,7 +9,7 @@
// - .A - must load FAC1 exponent ($61) beforehand to set the zero flag
//
// Note:
// - load FAC2 after FAC1, or mimic the Kernals sign comparison
// - load FAC2 after FAC1, or mimic the Kernals sign comparison (XXX do we need it?)
// - uses exp(x*log(y)) formula to calculate y^x; slow and inaccurate
//
// See also:
c64/basic/math/ba8c.CONUPK.s
+5 -7
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@@ -11,10 +11,10 @@
//
// Output:
// - .A - FAC1 exponent (yes, really - Codebase64 is right)
// - .Y - XXX 0?
// - .Y - 0 (experimentation with original ROM)
//
// Preserves:
// - .X - (experimentation with original routine)
// - .X - (experimentation with original ROM)
//
// See also:
// - [CM64] Computes Mapping the Commodore 64 - page 114
@@ -26,11 +26,11 @@
CONUPK:
// Not sure which temporary variables are used for storage by the original ROMs,
// but $22/$23 (INDEX+0 and INDEX+1) seem to be good candidates, at least some
// math routines use them as pointer storage, see:
// Checked in the available documentation:
// - https://www.c64-wiki.com/wiki/Floating_point_arithmetic
// - https://www.lemon64.com/forum/viewtopic.php?t=67576&sid=d41e77cdddd28d6f9c9d52ce5b4e8dc3
// that $22/$23 (INDEX+0 and INDEX+1) are at least sometimes used for pointer storage.
// Confirmed by experimenting with original ROM that this is the case here too.
sty INDEX+1
sta INDEX+0
@@ -38,8 +38,6 @@ CONUPK:
// Now copy the data from RAM to FAC2, for the format description see:
// - https://www.c64-wiki.com/wiki/Floating_point_arithmetic#Representation_in_the_C-64
ldy #$04
// Copy the mantissa - reverse byte order
ldy #$04
c64/basic/,stubs_math/ba8c.CONUPK.s → c64/basic/math/bba2.MOVFM.s
+22 -19
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@@ -2,35 +2,32 @@
// #LAYOUT# * BASIC_0 #TAKE
// #LAYOUT# * * #IGNORE
//
// Math package - fetch FAC2 from RAM location
// Math package - fetch FAC1 from RAM location
//
// Input:
// - .A - address low byte
// - .Y - address high byte
//
// Output:
// - .A - FAC1 exponent (yes, really - Codebase64 is right)
// - .Y - 0 (tested with original ROMs)
// - .A - FAC1 exponent, affects status flags
// - .Y - always 0
//
// Preserves:
// - .X (tested with original ROMs)
// - .X - (experimentation with original ROM)
//
// See also:
// - [CM64] Computes Mapping the Commodore 64 - page 114
// - https://www.c64-wiki.com/wiki/Floating_point_arithmetic
// - https://codebase64.org/doku.php?id=base:kernal_floating_point_mathematics
//
// XXX test this
CONUPK:
MOVMF:
// Noticed in the avilable materials:
// Checked in the available documentation:
// - https://www.c64-wiki.com/wiki/Floating_point_arithmetic
// - https://www.lemon64.com/forum/viewtopic.php?t=67576&sid=d41e77cdddd28d6f9c9d52ce5b4e8dc3
// that at least some math routines use $22/$23 (INDEX+0 and INDEX+1) for pointer storage,
// confirmed that this routine is not an exception
// that $22/$23 (INDEX+0 and INDEX+1) are at least sometimes used for pointer storage.
// Confirmed by experimenting with original ROM that this is the case here too.
sty INDEX+1
sta INDEX+0
@@ -38,26 +35,24 @@ CONUPK:
// Now copy the data from RAM to FAC2, for the format description see:
// - https://www.c64-wiki.com/wiki/Floating_point_arithmetic#Representation_in_the_C-64
ldy #$04
// Copy the mantissa - reverse byte order
ldy #$04
lda (INDEX), y
sta FAC2_mantissa+3
sta FAC1_mantissa+3
dey
lda (INDEX), y
sta FAC2_mantissa+2
sta FAC1_mantissa+2
dey
lda (INDEX), y
sta FAC2_mantissa+1
sta FAC1_mantissa+1
dey
lda (INDEX), y
ora #$80 // clear the sign bit
sta FAC2_mantissa+0
sta FAC1_mantissa+0
// Copy the sign
@@ -68,13 +63,21 @@ CONUPK:
!:
lda $00
sta FAC2_sign
sta FAC1_sign
// Copy the exponent
dey
lda (INDEX), y
sta FAC2_exponent
sta FAC1_exponent
// Set low order mantissa - to my surprise original ROM seems to put 0 to FACOW - XXX why???
// Since we do not know the original value (lost due to variable format having one byte shorter
// mantissa than FAC1), it is probably best to put some approximate value here; putting $80
// would be risky in case rouding is performed later, $7F seems to be sane choice
lda #$7F
sta FACOV
// Return the FAC1 exponent
c64/basic/,stubs_math/bba2.interop → c64/basic/math/bba2.interop
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File renamed without changes.