/
bit32.go
141 lines (136 loc) · 3.13 KB
/
bit32.go
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package gluabit32
import (
"math/bits"
"github.com/yuin/gopher-lua"
)
func band(ls *lua.LState) uint32 {
x := ^uint32(0)
for i, top := 1, ls.GetTop(); i <= top; i += 1 {
x &= uint32(ls.CheckNumber(i))
}
return x
}
func fieldWidthMaskArg(ls *lua.LState, arg int) (uint32, uint32) {
field := int32(ls.CheckNumber(arg))
if field < 0 {
ls.RaiseError("field cannot be negative")
}
var width int32
lwidth := ls.Get(arg + 1)
if w, ok := lwidth.(lua.LNumber); ok {
if w <= 0 {
ls.RaiseError("width must be positive")
}
width = int32(w)
} else if lwidth == lua.LNil {
width = 1
} else {
ls.RaiseError("invalid width type")
return 0, 0
}
if field+width > 32 {
ls.RaiseError("trying to access non-existent bits")
}
return uint32(field), ^(^uint32(0) << uint32(width))
}
func Loader(ls *lua.LState) int {
m := ls.SetFuncs(ls.NewTable(), map[string]lua.LGFunction{
"arshift": Bit32arshift,
"band": Bit32band,
"bnot": Bit32bnot,
"bor": Bit32bor,
"btest": Bit32btest,
"bxor": Bit32bxor,
"extract": Bit32extract,
"replace": Bit32replace,
"lrotate": Bit32lrotate,
"lshift": Bit32lshift,
"rrotate": Bit32rrotate,
"rshift": Bit32rshift,
})
ls.Push(m)
return 1
}
func Bit32arshift(ls *lua.LState) int {
x := int32(ls.CheckNumber(1))
disp := int32(ls.CheckNumber(2))
if disp >= 0 {
ls.Push(lua.LNumber(uint32(x >> disp)))
} else {
ls.Push(lua.LNumber(uint32(x) << -disp))
}
return 1
}
func Bit32band(ls *lua.LState) int {
ls.Push(lua.LNumber(band(ls)))
return 1
}
func Bit32bnot(ls *lua.LState) int {
ls.Push(lua.LNumber(^uint32(ls.CheckNumber(1))))
return 1
}
func Bit32bor(ls *lua.LState) int {
x := uint32(0)
for i, top := 1, ls.GetTop(); i <= top; i += 1 {
x |= uint32(ls.CheckNumber(i))
}
ls.Push(lua.LNumber(x))
return 1
}
func Bit32btest(ls *lua.LState) int {
ls.Push(lua.LBool(band(ls) != 0))
return 1
}
func Bit32bxor(ls *lua.LState) int {
x := uint32(0)
for i, top := 1, ls.GetTop(); i <= top; i += 1 {
x ^= uint32(ls.CheckNumber(i))
}
ls.Push(lua.LNumber(x))
return 1
}
func Bit32extract(ls *lua.LState) int {
n := uint32(ls.CheckNumber(1))
field, m := fieldWidthMaskArg(ls, 2)
ls.Push(lua.LNumber((n >> field) & m))
return 1
}
func Bit32lrotate(ls *lua.LState) int {
x := uint32(ls.CheckNumber(1))
k := int(ls.CheckNumber(2))
ls.Push(lua.LNumber(bits.RotateLeft32(x, k)))
return 1
}
func Bit32lshift(ls *lua.LState) int {
x := uint32(ls.CheckNumber(1))
disp := int32(ls.CheckNumber(2))
if disp >= 0 {
ls.Push(lua.LNumber(x << disp))
} else {
ls.Push(lua.LNumber(x >> -disp))
}
return 1
}
func Bit32replace(ls *lua.LState) int {
n := uint32(ls.CheckNumber(1))
v := uint32(ls.CheckNumber(2))
field, m := fieldWidthMaskArg(ls, 3)
ls.Push(lua.LNumber((n & ^(m << field)) | ((v & m) << field)))
return 1
}
func Bit32rrotate(ls *lua.LState) int {
x := uint32(ls.CheckNumber(1))
k := int(ls.CheckNumber(2))
ls.Push(lua.LNumber(bits.RotateLeft32(x, -k)))
return 1
}
func Bit32rshift(ls *lua.LState) int {
x := uint32(ls.CheckNumber(1))
disp := int32(ls.CheckNumber(2))
if disp >= 0 {
ls.Push(lua.LNumber(x >> disp))
} else {
ls.Push(lua.LNumber(x << -disp))
}
return 1
}