86 lines
1.7 KiB
Lua
86 lines
1.7 KiB
Lua
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local t = {}
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-- internal state
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--- program counter (pc)
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--- current instruction (ci) -- only passed from the environment to the emulator
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--- stack (stack)
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local function pop(s)
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return table.remove(s,#s) or 0
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end
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local function push(s,v)
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v=v or 0
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s[#s+1] = v%4096
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if #s > 16 then
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table.remove(s,1)
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end
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end
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function t.run(stab)
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-- variables
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local pc = stab.pc or 1
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local ci = stab.cins or 0
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local stack = stab.stack or {}
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local rstack = stab.rstack or {}
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local pci = 1
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local rw = nil
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local addr = 0
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local dat = 0
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-- instruction processing
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if ci == 4095 then -- ppc
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push(stack,pc)
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elseif ci == 4094 then -- swp
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a=pop(stack)
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b=pop(stack)
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push(stack,a)
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pusk(stack,b)
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elseif ci == 4093 then -- read
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rw = "read" -- terrible IPC
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addr = pop(stack)
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elseif ci == 4092 then -- write
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rw = "write"
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addr = pop(stack)
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dat = pop(stack)
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elseif ci == 4091 then -- add
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push(stack,pop(stack)+pop(stack))
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elseif ci == 4090 then -- sub
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push(stack,pop(stack)+pop(stack))
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elseif ci == 4089 then -- jmp
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pc = pop(stack)
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pci = 0
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elseif ci == 4088 then -- sez
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if pop(stack) == 0 then
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pci = pci + 1
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end
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elseif ci == 4087 then -- jez
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local a = pop(stack)
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if pop(stack) == 0 then
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pc = a
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pci = 0
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end
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elseif ci == 4086 then -- jsr
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push(rstack,pc)
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pc = pop(stack)
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pci = 0
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elseif ci == 4085 then -- ret
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pc = pop(rstack)
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elseif ci == 4084 then -- dup
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local v = pop(stack)
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push(stack,v)
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push(stack,v)
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elseif ci == 4083 then -- drop
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pop(stack)
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elseif ci == 4082 then -- hlt
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rw = "halt"
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else
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push(stack,ci)
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end
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-- return stuff
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stab = {}
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stab.pc = pc + pci -- increment pc
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stab.cins = 0
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stab.stack = stack
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stab.rstack = rstack
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return stab, rw, addr, dat
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end
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return t
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