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add bitrange function to make code a little clearer

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Connor Olding 2015-12-02 09:09:44 -08:00
parent 08472cdc1a
commit 3d28e95707
1 changed files with 25 additions and 19 deletions
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44
lips.lua
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@ -12,6 +12,8 @@ local assembler = {
]], ]],
} }
local floor = math.floor
local Class = function(inherit) local Class = function(inherit)
local class = {} local class = {}
local mt_obj = {__index = class} local mt_obj = {__index = class}
@ -27,6 +29,10 @@ local Class = function(inherit)
return setmetatable(class, mt_class) return setmetatable(class, mt_class)
end end
local function bitrange(x, lower, upper)
return floor(x/2^lower) % 2^(upper - lower + 1)
end
local registers = { local registers = {
[0]= [0]=
'R0', 'AT', 'V0', 'V1', 'A0', 'A1', 'A2', 'A3', 'R0', 'AT', 'V0', 'V1', 'A0', 'A1', 'A2', 'A3',
@ -1280,14 +1286,14 @@ function Dumper:add_directive(line, name, a, b)
if name == 'BYTE' then if name == 'BYTE' then
self:add_bytes(line, a % 0x100) self:add_bytes(line, a % 0x100)
elseif name == 'HALFWORD' then elseif name == 'HALFWORD' then
local b0 = a % 0x100 local b0 = bitrange(a, 0, 7)
local b1 = math.floor(a/0x100) % 0x100 local b1 = bitrange(a, 8, 15)
self:add_bytes(line, b1, b0) self:add_bytes(line, b1, b0)
elseif name == 'WORD' then elseif name == 'WORD' then
local b0 = a % 0x100 local b0 = bitrange(a, 0, 7)
local b1 = math.floor(a/0x100) % 0x100 local b1 = bitrange(a, 8, 15)
local b2 = math.floor(a/0x10000) % 0x100 local b2 = bitrange(a, 16, 23)
local b3 = math.floor(a/0x1000000) % 0x100 local b3 = bitrange(a, 24, 31)
self:add_bytes(line, b3, b2, b1, b0) self:add_bytes(line, b3, b2, b1, b0)
elseif name == 'ORG' then elseif name == 'ORG' then
t.kind = 'goto' t.kind = 'goto'
@ -1327,8 +1333,8 @@ function Dumper:desym(tok)
elseif tok[1] == 'LABELSYM' then elseif tok[1] == 'LABELSYM' then
return self.labels[tok[2]] return self.labels[tok[2]]
elseif tok[1] == 'LABELREL' then elseif tok[1] == 'LABELREL' then
local rel = math.floor(self.labels[tok[2]]/4) local rel = floor(self.labels[tok[2]]/4)
rel = rel - 1 - math.floor(self.pos/4) rel = rel - 1 - floor(self.pos/4)
if rel > 0x8000 or rel <= -0x8000 then if rel > 0x8000 or rel <= -0x8000 then
self:error('branch too far') self:error('branch too far')
end end
@ -1351,14 +1357,14 @@ function Dumper:toval(tok)
end end
if tok[1] == 'UPPER' then if tok[1] == 'UPPER' then
local val = self:desym(tok[2]) local val = self:desym(tok[2])
return math.floor(val/0x10000) return bitrange(val, 16, 31)
elseif tok[1] == 'LOWER' then elseif tok[1] == 'LOWER' then
local val = self:desym(tok[2]) local val = self:desym(tok[2])
return val % 0x10000 return bitrange(val, 0, 15)
elseif tok[1] == 'UPPEROFF' then elseif tok[1] == 'UPPEROFF' then
local val = self:desym(tok[2]) local val = self:desym(tok[2])
local upper = math.floor(val/0x10000) local upper = bitrange(val, 16, 31)
local lower = val % 0x10000 local lower = bitrange(val, 0, 15)
if lower >= 0x8000 then if lower >= 0x8000 then
-- accommodate for offsets being signed -- accommodate for offsets being signed
upper = (upper + 1) % 0x10000 upper = (upper + 1) % 0x10000
@ -1378,7 +1384,7 @@ function Dumper:toval(tok)
return val % 0x10000 return val % 0x10000
elseif tok[1] == 'INDEX' then elseif tok[1] == 'INDEX' then
local val = self:desym(tok[2]) % 0x80000000 local val = self:desym(tok[2]) % 0x80000000
val = math.floor(val/4) val = floor(val/4)
return val return val
else else
return self:desym(tok) return self:desym(tok)
@ -1427,8 +1433,8 @@ function Dumper:dump_instruction(t)
if #t == 2 then if #t == 2 then
local val = self:valvar(t[2], 26) local val = self:valvar(t[2], 26)
uw = uw + math.floor(val/0x10000) uw = uw + bitrange(val, 16, 25)
lw = lw + val % 0x10000 lw = lw + bitrange(val, 0, 15)
elseif #t == 4 then elseif #t == 4 then
uw = uw + self:valvar(t[2], 5)*0x20 uw = uw + self:valvar(t[2], 5)*0x20
uw = uw + self:valvar(t[3], 5) uw = uw + self:valvar(t[3], 5)
@ -1460,10 +1466,10 @@ function Dumper:dump()
self.line = t.line self.line = t.line
if t.kind == 'instruction' then if t.kind == 'instruction' then
uw, lw = self:dump_instruction(t) uw, lw = self:dump_instruction(t)
local b0 = lw % 0x100 local b0 = bitrange(lw, 0, 7)
local b1 = math.floor(lw/0x100) local b1 = bitrange(lw, 8, 15)
local b2 = uw % 0x100 local b2 = bitrange(uw, 0, 7)
local b3 = math.floor(uw/0x100) local b3 = bitrange(uw, 8, 15)
self:write{b3, b2, b1, b0} self:write{b3, b2, b1, b0}
elseif t.kind == 'bytes' then elseif t.kind == 'bytes' then
self:write(t) self:write(t)