performance-aware/decoder8086.odin

73 lines
1.9 KiB
Odin

package decoder_8086
import "core:os"
import "core:fmt"
Register :: struct {
fullname: string,
bytename: string,
value: struct #raw_union {
using _: struct {
low, high: byte,
},
full: u16,
},
code: u8,
}
registers := [8]Register {
{fullname = "ax", bytename = "al", code = 0b000},
{fullname = "cx", bytename = "cl", code = 0b001},
{fullname = "dx", bytename = "dl", code = 0b010},
{fullname = "bx", bytename = "bl", code = 0b011},
{fullname = "sp", bytename = "ah", code = 0b100},
{fullname = "bp", bytename = "ch", code = 0b101},
{fullname = "si", bytename = "dh", code = 0b110},
{fullname = "di", bytename = "bh", code = 0b111},
}
main :: proc() {
ax := registers[0]
ax.value.full = 52428
f,err := os.open(len(os.args) > 1 ? os.args[1] : "./asm_files/01-01-38.bin")
if err != os.ERROR_NONE {
os.exit(1)
}
defer os.close(f)
data := make([]u8, 256)
bytes_read, err2 := os.read(f, data)
if err2 != nil {
// ...
os.exit(1)
}
// mov cx, bx ; mov 001, 011
// mov dx, bx
read_next := false
src_dst := true
is_word := false
prev :u8 = 0
fmt.println("bits 16\n")
for b in data {
if read_next {
mod := (b & 0b11000000) >> 6
reg := (b & 0b00111000) >> 3
rm := b & 0b00000111
src_name := is_word ? registers[reg].fullname : registers[reg].bytename
dst_name := is_word ? registers[rm].fullname : registers[rm].bytename
fmt.printfln("mov %s, %s ;; %b %b", dst_name, src_name, prev, b)
read_next = false
continue
}
if b == 0b10001001 {
read_next = true
is_word = true
} else if b == 0b10001000 {
read_next = true
is_word = false
}
prev = b
}
}