Integers
- i8
- u8
- i16
- u16
- i32
- u32
- i64
- u64
Integers are encoded in the usual way. Unsigned integers count up starting from zero, and signed integers are stored in two's compliment fashion.
Floats
- f32
- f64
Floating point numbers are stored using the typical IEEE 754 standard.
Words
- byte (8 bits)
- qword (16 bits)
- hword (32 bits)
- word (64 bits)
Words are just generic bits of data, without any preassigned meaning. They can be whatever you want! Might be text, might represent a color, or something more!
Immediates
Word immediate
|--------|--------|--------|--------|--------|--------|--------|--------|
i....... ........ ........ ........ ........ ........ ........ ........
Hword immediate
|--------|--------|--------|--------|
i....... ........ ........ ..r.....
|--------|--------|--------|--------|
i....... ........ ........ ........
|--------|--------|--------|--------|
00000000 00000000 i....... ........
|--------|--------|--------|--------|
00000000 00000000 00000000 i.......
i
is the binary content of the immediate valuer
is an unsigned 6-bit value that indicates how muchi
should be left-rotated to form the true value of the encoded immediate (only applicable to hword immediates which are encoding a word value.
The general logic behind this encoding is...
-
If the size of the word being stored is less than or equal to the available size for encoding the immediate, it should be stored exactly, aligned to the least significant digits, and padded with zeroes in the unused most significant digits, including cases where the value is a signed integer.
-
If the size of the word being stored is greater than the available size for encoding the immediate, then the first n least significant bits should be used to store an unsigned integer indicating how many digits to the left the partial value should be rotated, where s is the size of the word in bits and n is ⌈log2(s)⌉, and the remaining available bits should be used to store exact binary data.
A few examples...
- An i8 with a value of -1 would be encoded as
00000000 00000000 00000000 11111111
- An i64,u64 with a value of 1 could be encoded as
00000000 00000000 00000000 01000000
- An i64,u64 with a value of 0xf0 could be encoded as
00000000 00000000 00000011 11000100
- A u64 with a value of 0x8000000000000001 could be encoded as
00000000 00000000 00000000 11111111
Caveats
- f64 values cannot be stored in an hword immediate, and must be addressed as a fwi.