🧠 C Assembler – Complete Two-Pass Architecture with Macro Expansion and Base64 Output

A complete two-pass assembler written entirely in C by Hillel Suied, designed to process .as source files, expand macros, resolve labels, encode instructions into binary, and generate output in Base64.

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🛠 Features

• ✅ Macro expansion system (mcro ... endmcro)
• ✅ Two-pass assembly: label handling and resolution
• ✅ Instruction & data separation using IC / DC counters
• ✅ 16-bit binary encoding of instructions and operands
• ✅ Base64 output for .ob object files
• ✅ Generation of .am, .ob, .ent, .ext files
• ✅ Clean modular structure

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🔄 How It Works

1. Macro Expansion

   • Input: .as file
   • Output: .am file
   • All macros are expanded before parsing instructions.

2. First Pass

   • Scans .am file line by line
   • Builds symbol table and collects labels
   • Creates instruction/data memory (IC/DC)

3. Second Pass

   • Resolves labels and deferred references
   • Encodes each line into binary using shifting and bit masks

4. Output

   • Base64 encoding of 16-bit binary values
   • Writes to .ob, .ent, and .ext files

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📁 File Structure

File	Description
main.c	Entry point
macro.c/h	Macro handling
assembler.c/h	Two-pass logic
binary.c/h	Instruction encoding
insert.c/h	IC / DC list management
Label.c/h	Label structures
maybeLabel.c/h	Deferred label resolution
printToFile.c/h	Output writer to Base64
base64.c/h	Binary → Base64
wordChecks.c/h	Syntax validation
lineFix.c/h	Input line formatting
Free.c/h	Memory deallocation
makefile	Automated compilation
test1.as	Sample input file

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📸 Example

Input (test1.as):

mcro M1
mov r1, r2
endmcro
M1
stop

Output (test1.ob):

104 2
QG
e/

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🚀 Build & Run

make
./assembler test1

Output Files:

• test1.am – After macro expansion
• test1.ob – Base64-encoded object file
• test1.ent / test1.ext – If entry/external labels used

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🗺️ Visual Diagram

You can include flowchart.png to illustrate the assembler's architecture from input to output.

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👨‍💻 Author

Built from scratch by Hillel Suied
Focus on memory management, bitwise operations, file handling, and clean modular architecture in C.

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📜 License

MIT – Free to use and modify with attribution.