Remove X instruction.
Chris Pressey
5 years ago
| 178 | 178 |
| 0^^^0vv
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| 179 | 179 |
= > 0:[-2,3]
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| 180 | 180 |
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| 181 | |
The instruction `X` pops a value from the current stack, doubles
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| 182 | |
it, and pushes the result back onto the current stack.
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| 183 | |
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| 184 | |
| 0^XXXX
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| 185 | |
= > 0:[16]
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| 186 | |
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| 187 | 181 |
The instruction `:` pops a value from the current stack and pushes
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| 188 | 182 |
two copies of the value back on the stack.
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| 189 | 183 |
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| 190 | |
| 0^XXX:^
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|
184 |
| 0^^^^^^^^:^
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| 191 | 185 |
= > 0:[9,8]
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| 192 | 186 |
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| 193 | 187 |
The instruction `$` pops a value from the current stack and discards
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| 194 | 188 |
it.
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| 195 | 189 |
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| 196 | |
| 0^XXX$
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|
190 |
| 0^^^^^$
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| 197 | 191 |
=
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| 198 | 192 |
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| 199 | 193 |
The instruction `\\` pops the top two values, swaps them, and pushes
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| 200 | 194 |
them back on the stack.
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| 201 | 195 |
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| 202 | |
| 0^XXX0^\0^^
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|
196 |
| 0^^^^^^^^0^\0^^
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| 203 | 197 |
= > 0:[2,8,1]
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| 204 | 198 |
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| 205 | 199 |
### Navigating the stacks
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|
| 207 | 201 |
The instruction `<` (resp `>`) moves one space left (resp. right)
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| 208 | 202 |
on the tape, changing which stack is the current stack.
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| 209 | 203 |
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| 210 | |
| 0^XX<0^XXX<0^XXXX>
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| 211 | |
= -2:[16]
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|
204 |
| 0^^^^<0^^^^^^^^<0^^^^^^^^^^>
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|
205 |
= -2:[10]
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| 212 | 206 |
= >-1:[8]
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| 213 | 207 |
= 0:[4]
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| 214 | 208 |
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|
| 216 | 210 |
moves one space left (resp. right) on the tape, and pushes the value
|
| 217 | 211 |
onto the new current stack.
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| 218 | 212 |
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| 219 | |
| 0^XX<0^XXX(0^XXXX)
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|
213 |
| 0^^^^<0^^^^^^^^(0^^^^^^^^^^)
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| 220 | 214 |
= -2:[8]
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| 221 | |
= >-1:[16]
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|
215 |
= >-1:[10]
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| 222 | 216 |
= 0:[4]
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| 223 | 217 |
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| 224 | 218 |
The instruction `'` (apostrophe) makes stack zero (the stack that
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|
| 438 | 432 |
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| 439 | 433 |
One could say that "Core Oxcart" omits the following operations:
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| 440 | 434 |
|
| 441 | |
X<>\\'
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| 442 | |
|
| 443 | |
`X` can probably be implemented with a loop.
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|
435 |
<>\\'
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| 444 | 436 |
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| 445 | 437 |
`<` and `>` can be thought of as just shorthands for `0v0^Y` and
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| 446 | 438 |
`0^0^Y`.
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| 40 | 40 |
push0 st k = k $ push (Num 0) st
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| 41 | 41 |
incr st k = let (Just (Num n), st') = pop st in k (push (Num (n+1)) st')
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| 42 | 42 |
decr st k = let (Just (Num n), st') = pop st in k (push (Num (n-1)) st')
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| 43 | |
dbl st k = let (Just (Num n), st') = pop st in k (push (Num (n*2)) st')
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| 44 | 43 |
dup st k = let (Just v, st') = pop st in k (push v (push v st'))
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| 45 | 44 |
pop' st k = let (Just v, st') = pop st in k st'
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| 46 | 45 |
swap st k =
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| 99 | 98 |
m' '0' = push0
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| 100 | 99 |
m' '^' = incr
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| 101 | 100 |
m' 'v' = decr
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| 102 | |
m' 'X' = dbl
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| 103 | 101 |
m' ':' = dup
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| 104 | 102 |
m' '$' = pop'
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| 105 | 103 |
m' '\\' = swap
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