268 lines
6.2 KiB
Ruby
268 lines
6.2 KiB
Ruby
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# assembler.rb
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# # # REGISTER NAMES # # #
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def r0() 0 end # zero
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def at() 1 end # assembler temporary
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# subroutine return values, may be changed by subroutines
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def v0() 2 end ; def v1() 3 end
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# subroutine arguments, may be changed by subroutines
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def a0() 4 end ; def a1() 5 end
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def a2() 6 end ; def a3() 7 end
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# temporaries, may be changed by subroutines
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def t0() 8 end ; def t1() 9 end
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def t2() 10 end ; def t3() 11 end
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def t4() 12 end ; def t5() 13 end
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def t6() 14 end ; def t7() 15 end
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# static variables, must be saved by subs
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def s0() 16 end ; def s1() 17 end
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def s2() 18 end ; def s3() 19 end
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def s4() 20 end ; def s5() 21 end
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def s6() 22 end ; def s7() 23 end
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# temporaries, may be changed by subroutines
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def t8() 24 end ; def t9() 25 end
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# reserved for kernel, detroyed by some irq handlers
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def k0() 26 end ; def k1() 27 end
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def gp() 28 end # global pointer, rarely used (we can use this to reffer to a struct or smtn)
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def sp() 29 end # stack pointer
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def fp() 30 end # frame pointer
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def ra() 31 end # return address
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class Assembler
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def initialize(base, size)
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@base_addr = base
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@file_size = size
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# moar vars defined in assemble()
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end
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def inspect
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"(Assembler base_addr:0x#{@base_addr.to_s 16} file_size:0x#{@file_size.to_s 16})"
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end
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def label(l)
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l = l.to_s
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@sub_labels[l] = {} if not @sub_labels.member?(l)
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@last_label_subs = @sub_labels[l]
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return if @first_pass == false
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raise "error redefinition of label #{l}" if @labels.member?(l)
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@labels[l] = @bytes.length + @base_addr
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end
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def sub_label(l)
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return if @first_pass == false
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l = l.to_s
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raise "error redefinition of sub_label #{l}" if @last_label_subs.member?(l)
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@last_label_subs[l] = @bytes.length + @base_addr
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end
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def method_missing(m, *args, &block)
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return 0 if @first_pass
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if @last_label_subs[m.to_s] then
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return @last_label_subs[m.to_s]
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elsif @labels.member?(m.to_s) then # if m.to_s[0, 2] == "l_" then
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return @labels[m.to_s] #return @labels[m.to_s[2..]] if @labels.member?(m.to_s[2..])
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#raise "label doesn't exist #{m.to_s}"
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else
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super
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end
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end
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def assemble(source)
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@first_pass = true
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@labels = {}
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@bytes = []
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@sub_labels = {}
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@last_label_subs = {}
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binding.eval source
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@first_pass = false
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@bytes = []
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@last_label_subs = {}
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binding.eval source
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puts "assembled 0x#{@bytes.length.to_s 16} (#{@bytes.length}) bytes"
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raise "CODE IS GREATER THAN FILESIZE" if @bytes.length > @file_size
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zero_fill @file_size - 1
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return @bytes
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end
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def zero_fill(pos)
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while (@bytes.length <= pos) do
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@bytes.push(0)
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end
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end
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def word(i)
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@bytes.push((i & 0x000000ff),
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(i & 0x0000ff00) >> 8,
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(i & 0x00ff0000) >> 16,
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(i & 0xff000000) >> 24)
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end
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def string(s)
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@bytes.push *s.bytes
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@bytes.push 0 # null terminate
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while ((@bytes.length % 4) != 0) do
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@bytes.push 0
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end
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end
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# # # INSTRUCTIONS # # #
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# ops should always be in format of
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# [src] [args] -> [dest]
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def jmp(addr)
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# TODO: this probs wont show up since we have < 3mb of ram but
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# we can't jump to an address with a different 4 most significant bits
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raise "jmp addr must be 4 byte aligned" if addr % 4 != 0
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op = 0b0000_1000_0000_0000_0000_0000_0000_0000
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op = op | ((addr >> 2) & 0b11_11111111_11111111_11111111)
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word op
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end
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def jal(addr)
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# TODO: same problem as jmp
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raise "jmp addr must be 4 byte aligned" if addr % 4 != 0
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op = 0b0000_1100_0000_0000_0000_0000_0000_0000
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op = op | ((addr >> 2) & 0b11_11111111_11111111_11111111)
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word op
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end
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# load upper immediate
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# NOTE: val will be shifted left by 16
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def lui(val, dest)
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# oooooo ----- ddddd iiiiiiiiiiiiiiii
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op = 0b001111_00000_00000_0000000000000000
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op |= 0xffff & val
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op |= (0b11111 & dest) << 16
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word op
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end
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# shift right logical
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def srl(src, amt, dest)
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# oooooo ----- sssss ddddd hhhhh oooooo
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op = 0b000000_00000_00000_00000_00000_000010
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op |= (src & 0b11111) << 16
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op |= (amt & 0b11111) << 6
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op |= (dest & 0b11111) << 11
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word op
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end
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# or immediate
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def ori(src, bits, dest)
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# oooooo sssss ddddd iiiiiiii iiiiiiii
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op = 0b001101_00000_00000_00000000_00000000
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op |= (src & 0b11111) << 21
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op |= (bits & 0xffff)
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op |= (dest & 0b11111) << 16
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word op
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end
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# store word
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# NOTE: this doesn't work unaligned
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def sw(src, offset, dest)
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# oooooo ddddd sssss iiiiiiii iiiiiiii
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op = 0b101011_00000_00000_00000000_00000000
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op |= (src & 0b11111) << 16
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op |= (offset & 0xffff)
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op |= (dest & 0b11111) << 21
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word op
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end
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# add immediate unsigned
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def addiu(src, val, dest)
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# oooooo sssss ddddd iiiiiiii iiiiiiii
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op = 0b001001_00000_00000_00000000_00000000
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op |= (src & 0b11111) << 21
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op |= (val & 0xffff)
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op |= (dest & 0b11111) << 16
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word op
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end
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# add immediate
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def addi(src, val, dest)
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# oooooo sssss ddddd iiiiiiii iiiiiiii
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op = 0b001000_00000_00000_00000000_00000000
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op |= (src & 0b11111) << 21
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op |= (val & 0xffff)
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op |= (dest & 0b11111) << 16
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word op
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end
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# jump register
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def jr(reg)
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# oooooo rrrrr ----- ----- ----- oooooo
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op = 0b000000_00000_00000_00000_00000_001000
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op |= (reg & 0b11111) << 21
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word op
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end
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# TODO: actually encode "comment" argument
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def syscall(comment)
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# iiiiii ccccc ccccc ccccc ccccc iiiiii
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op = 0b000000_00000_00000_00000_00000_001100
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word op
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end
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# TODO: expose the return address storage register
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# NOTE: cannot use the same register for both operands
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def jalr(reg)
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# jumps to addr in j and stores return adr in r
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# iiiiii jjjjj ----- rrrrr ----- iiiiii
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op = 0b000000_00000_00000_00000_00000_001001
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op |= (reg & 0b11111) << 21
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op |= (ra) << 11 # ra
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word op
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end
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# # # PSEUDO-INSTRUCTIONS # # #
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def nop
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word 0x00000000
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end
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# load immediate
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# TODO: check if we need to use 1 or 2 ops and output that
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def li(dest, val)
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lui val >> 16, dest
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ori dest, val, dest
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end
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end
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# # # CONSTANTS # # #
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base_addr = 0x80010000 # 0x10000 # 0x80010000
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file_size = 0x800 * 3
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f = File.new "exe-header.asm.rb", "r"
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exe_header = Assembler.new(base_addr, 0x800).assemble f.read
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# puts f.path
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f.close
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f = File.new "main.asm.rb", "r"
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binary = Assembler.new(base_addr, file_size).assemble f.read
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f.close
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f = File.new "LOADTHIS.EXE", "wb"
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f.write exe_header.pack("C*")
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f.write binary.pack("C*")
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f.close
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