# Preface:
This document is a scratch space for the design of the switch action.
It may be out of date and is kept around for posterity.
.syntax:
----
(switch
(or a b c) (cmd <cmd1>) break
(and a b (or c d)) (cmd <cmd2>) fallthrough
(and a b (or c d) (or e f)) fallthrough
()
)
----
.opcode format examples:
----
(or a b c)
OR-4 a b c
(and a b (or c d))
AND-6 a b OR-6 c d
(and a b (or c d) (or e f))
AND-9 a b OR-6 c d OR-9 e f
----
.opcodes:
----
key: all values < 1024
OR/AND: OP & 0xF000
OR : 0x1000
AND: 0x2000
length: OP & 0x0FFF
----
.Rough algorithm for opcodes:
----
value=true
push first opcode
WHILE stack is not empty
WHILE index <= ending_index
switch
opcode:
push, continue
key(OR):
value=true: skip to index, pop
value=false: continue
key(AND):
value=true: continue
value=false: skip to index, pop
pop
switch
current_value(OR):
value=true: skip to index, pop
value=false: continue
current_value(AND):
value=true: continue
value=false: skip to index, pop
return value
----
.statestruct:
----
value
current_index
current_end_index
current_op
stack (op, ending_index)
----
.rough sequence 1:
----
pressed: y y y y y y
opcodes: AND-9 a b OR-6 c d OR-9 e f
index: 0
push: AND-9
stack: AND-9
index: 1
val: true
index: 2
val: true
index: 3
push: OR-6
stack: AND-9 OR-6
index: 4
val: true
skip to 6
pop
stack: AND-9
index: 6
push: OR-9
stack: AND-9 OR-9
index: 7
val: true
skip to 9
pop
stack: AND-9-true
index 9:
pop
stack: empty
return val: true
----
.rough sequence 2:
----
pressed: y y n n y y
opcodes: AND-9 a b OR-6 c d OR-9 e f
index: 0
push: AND-9
stack: AND-9
index: 1
val: true
index: 2
val: true
index: 3
push: OR-6
stack: AND-9 OR-6
val: true
index: 4
val: false
index: 5
val: false
index: 6
val: false
pop
stack: AND-9
skip to 9
pop
stack: empty
return val: false
----
.rough sequence 3:
----
pressed: n y n n y y
opcodes: AND-9 a b OR-6 c d OR-9 e f
index: 0
push: AND-9
stack: AND-9
index: 1
val: false
skip to 9
pop
stack: empty
return val: false
----
.pseudo code again:
----
let mut value = true
let mut current_index = 1
let mut current_end_index = first_opcode - end_index
let mut current_op = OR
while current_index < slice_length {
if index >= current_end_index:
if stack is empty:
break
else:
pop stack to current_op and current_end_index
switch
current_value(OR):
value=true: skip to current_end_index; continue
current_value(AND):
value=false: skip to current_end_index; continue
switch
opcode:
push (current_end_index,current_op)
update (current_end_index,current_op) with opcode
key(OR):
value=true: skip to current_end_index; continue
value=false
key(AND):
value=true
value=false: skip to current_end_index; continue
current_index++;
}
return value
----
