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clean up fix16

This commit is contained in:
~d6 2022-11-06 22:01:45 -05:00
parent 9f72ee4490
commit a870fc533a
2 changed files with 6 additions and 106 deletions
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53
fix16.tal
View File

@ -48,14 +48,12 @@
( MUL2. )
( )
( similarly with division we have: )
( )
( x divided by #0100 -> x )
( x divided by #0001 -> x * 256, with likely overfow )
( #abcd divided by #1000 -> #0abc, rounding with d )
( x divided by #0200 -> x >> 1 )
( x divided by #0080 -> x << 1 )
%xyz { ;x16-emit JSR2 #0a #18 DEO }
( )
( x = x'/256 )
( y = y'/256 )
( x/y = z = z'/256 )
( (x'/256)/(y'/256) = (x'*256 / y)/256 )
( z' = (x' * 256 / y)/256 )
( useful constants )
( )
@ -92,42 +90,6 @@
%x16-emit-dec { #30 ADD #18 DEO }
( |0100
x16-zero xyz
x16-one xyz
x16-two xyz
x16-ten xyz
x16-hundred xyz
x16-pi/2 xyz
x16-pi xyz
x16-pi*2 xyz
x16-e xyz
x16-phi xyz
x16-sqrt-2 xyz
x16-sqrt-3 xyz
x16-epsilon xyz
#0002 xyz
#1234 xyz
#7fff xyz
#8000 xyz
#8001 xyz
#ffff xyz
#0200 xyz
#0834 #0000 ;x16-add JSR2 xyz
#0834 #0834 ;x16-add JSR2 xyz
#0834 #0834 ;x16-mul JSR2 xyz
#0834 #0200 ;x16-div JSR2 xyz
#0100 xyz
#0003 xyz
#0100 #0003 ;x16-div JSR2 xyz
#0834 xyz
#0080 xyz
#0834 #0080 ;x16-div JSR2 xyz
#0834 xyz
#0300 xyz
#0834 #0300 ;x16-div JSR2 xyz
BRK )
@x16-emit ( x* -> )
DUP2 #8000 EQU2 ,&is-min JCN
DUP2 #8000 GTH2 ,&is-neg JCN
@ -201,9 +163,6 @@
&rhs-whole #08 SFT2 MUL2 JMP2r
@x16-div ( x* y* -> x/y* )
( DUP ,&not-whole JCN
#08 SFT2 DIV2 JMP2r ( since y is whole, x/(y>>8) is correct )
&not-whole )
DIV2k STH2k ( x y x/y {x/y} )
LITr 80 SFT2r ( x y x/y {div=(x/y)<<8 )
OVR2 STH2 ( x y x/y {y div} )

59
fixed.tal
View File

@ -1,59 +0,0 @@
( use short as a fixed point number 8.8 )
( )
( so #0001 is interpreted as 1/256 )
( and #ffff is interpreted as 255+255/256 )
( )
( x = x0 + x1/256 )
( y = y0 + y1/256 )
( )
( many 8.8 operations are equivalent to u16: )
( * comparisons/equality )
( * addition/subtraction )
( )
( but due to 16-bit truncation multiplication is different. )
( )
( x*y = x0*y0 + x0*y1/256 + x1*y0/256 + x1*y1/65536 )
( )
( since we only have 16-bits: )
( 1. we need to drop the 8 high bits from x0*y0 )
( 2. we need to drop the 8 low bits from x1*y1 )
( 3. we need to use all the bits from x0*y1 and x1*y0 )
%EMIT { #18 DEO }
%DIGIT { #00 SWP ;digits ADD2 LDA EMIT }
%SPACE { #20 EMIT }
%NEWLINE { #0a EMIT }
%EMIT-BYTE { DUP #04 SFT DIGIT #0f AND DIGIT }
( program )
|0100
#0100 #0100 ;mul-fix JSR2 ;emit-short JSR2 NEWLINE
#0999 #0100 ;mul-fix JSR2 ;emit-short JSR2 NEWLINE
#abcd #0100 ;mul-fix JSR2 ;emit-short JSR2 NEWLINE
#0200 #0200 ;mul-fix JSR2 ;emit-short JSR2 NEWLINE
#0400 #0200 ;mul-fix JSR2 ;emit-short JSR2 NEWLINE
BRK
%LO { NIP #00 SWP }
%HI { POP #00 SWP }
@mul-fix ( x* y* -> z* )
OVR2 OVR2 LO SWP2 LO MUL2 ( x1*y1 )
#08 SFT2 STH2 ( z = (x1*y1)>>8 )
OVR2 OVR2 HI SWP2 LO MUL2 ( x0*y1 )
STH2 ADD2r ( z += x0*y1 )
OVR2 OVR2 LO SWP2 HI MUL2 ( x1*y0 )
STH2 ADD2r ( z += x1*y0 )
HI SWP2 HI MUL2 ( x0*y0 )
#80 SFT2 STH2r ADD2 ( z += (x0*y0)<<8 )
JMP2r
@emit-short SWP EMIT-BYTE EMIT-BYTE JMP2r
( convenience for less branching when printing hex )
@digits
30 31 32 33 34 35 36 37
38 39 61 62 63 64 65 66