Re: How do I cast to from byte[] <-> double for making a small assembler language VM to work?
Thanks for the replies. I will look at 3-address opcodes and consider unions. *Wonders if it matters that Program is a struct with opSlice / opSliceAssign overloaded*.
Re: How do I cast to from byte[] <-> double for making a small assembler language VM to work?
Maybe use a union?
union U {
double d;
byte[double.sizeof] bytes;
}
U u;
u.bytes = ...;
double d = u.d;
... // do something with d
// or:
U u;
u.d = 3.14159;
byte[] b = u.bytes[];
... // do something with b
Casting a pointer may run into alignment issues, if your byte[] isn't
aligned to a double.
T
--
Only boring people get bored. -- JM
Re: How do I cast to from byte[] <-> double for making a small assembler language VM to work?
On Tuesday, 18 July 2017 at 11:06:22 UTC, Enjoys Math wrote: [ ... ] The cast at the bottom gives a compiler error (can't cast byte[] to double). If you want to see how it's done check: https://github.com/UplinkCoder/dmd/blob/newCTFE_on_master/src/ddmd/ctfe/bc.d Though if you have the choice I'd recommend proper 3-address opcodes.
Re: How do I cast to from byte[] <-> double for making a small assembler language VM to work?
On Tuesday, 18 July 2017 at 11:06:22 UTC, Enjoys Math wrote:
class OpCode
{
private:
byte[] bytes_;
public:
void opCall(Program program) const;
byte[] bytes() const {
return bytes_.dup;
}
}
class AddD : OpCode
{
private:
uint d, s;
public:
this(uint dst, uint src) {
d = dst;
s = src;
}
override void opCall(Program p) const
{
p[d..d+8] = cast(byte[])(cast(double)p[d..d+8] +
cast(double)p[s..s+8]);
}
}
---
The cast at the bottom gives a compiler error (can't cast
byte[] to double)
Byte[] is a slice
what you want is *(cast(double*)p + d) = *(cast(double*)p + d) +
*(cast(double*)p + s)
How do I cast to from byte[] <-> double for making a small assembler language VM to work?
class OpCode
{
private:
byte[] bytes_;
public:
void opCall(Program program) const;
byte[] bytes() const {
return bytes_.dup;
}
}
class AddD : OpCode
{
private:
uint d, s;
public:
this(uint dst, uint src) {
d = dst;
s = src;
}
override void opCall(Program p) const
{
p[d..d+8] = cast(byte[])(cast(double)p[d..d+8] +
cast(double)p[s..s+8]);
}
}
---
The cast at the bottom gives a compiler error (can't cast byte[]
to double).
