A two-pass assembler

1. Build and run the starter
   gcc -Wall -o sicasm sicasm_starter.c then ./sicasm count.asm. The output is wrong: that is expected.
2. TODO 1: SYMTAB
   Insert each label. Test with dup.asm: it must stop with "duplicate symbol FIRST".
3. TODO 2: LOCCTR
   Apply the size rules (slide 12). Check the LOC column against slide 13, and the length 00A0.
4. TODO 3: instructions
   Opcode, x bit, address, sprintf. Test with undef.asm: "undefined symbol BETA".
5. TODO 4: BYTE
   C'BANANA' → 42414E414E41, X'F1' → F1. Then every row of slide 16 must match.
6. Compare
   diff count.obj count_expected.obj prints nothing when your assembler is right. Then try sumn.asm.

Submit: your sicasm.c, the listing of sumn.asm, and sumn.obj.

1. Hand-assemble on paper
   Lines 0000–0032 of countx.asm. Write n i x b p e, the disp and the code. Check against slide 14.
2. Add -m to sicasm
   With ./sicasm -m file.asm, write M{loc+1}04 for every instruction with an operand.
3. Count them
   Run it on count.asm: you should get 13 M records. Compare with the 2 of countx.asm.
4. Relocate by hand
   Load count.obj at 5000 instead of 2000: add 3000 to each marked field. LDCH TEXT,X must become 50D027.
5. Write apply_m() in C
   void apply_m(unsigned char *mem, int addr, int halfbytes, int delta); Test it on count.obj.
6. Explain
   In 3 sentences: why does SIC need 13 M records and SIC/XE only 2? What would a big program look like?

Submit: your updated sicasm.c, count.obj with M records, and your apply_m() with a test.

1. EQU with a number
   MAXLEN EQU 6: put MAXLEN into SYMTAB with value 6. Its LOC column shows 0006.
2. EQU with * and A−B
   TEXTEND EQU *, TLEN EQU TEXTEND-TEXT. Write eval(): number, *, SYMBOL, SYMBOL−SYMBOL, SYMBOL+number.
3. LITTAB
   struct lit { char text[40]; int addr; int placed; }; Add a literal the first time it is seen.
4. LTORG and END
   Give every waiting literal an address and output it like a BYTE line marked *.
5. Pass 2
   An operand starting with = takes its address from LITTAB. Test: countlit.asm must match countlit_expected.obj.
6. Break it
   Put TLEN EQU TEXTEND-TEXT before TEXT. Your assembler must stop with an error, not print rubbish.

Submit: sicasm_v2.c, the listing and object program of countlit.asm, and the output of task 6.