Blåhaj32 is a smol little RISC-based ISA, and hardware collection, optimized for... well, nothing really, but it is meant to be very easy to understand :3
There are 32 registers, named r0 through r31. Each register is 32 bits wide and fully mutable,
except one, called r0, also referred to as the zero register. It is hardwired to always be zero
and cannot be mutated.
| Register | Symbolic Name |
|---|---|
r0 |
zero |
r1..r31 |
Reserved |
All instructions are currently 32 bits wide.
The following instruction formats exist:
| Format | Bit | |||||||||||||||||||||||||||||||
| 31 | 30 | 29 | 28 | 27 | 26 | 25 | 24 | 23 | 22 | 21 | 20 | 19 | 18 | 17 | 16 | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | |
| Register | f7 |
f3 |
rs2 | rs1 |
rd |
opcode |
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| Large Immediate | imm[19:0] |
f1 |
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| Immediate | imm[11:0] |
f4 |
rs1 |
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