https://github.com/jserv/full-stack-hello
minimal instruction set and assembler/compiler for "Hello World" execution
https://github.com/jserv/full-stack-hello
Last synced: about 2 months ago
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minimal instruction set and assembler/compiler for "Hello World" execution
- Host: GitHub
- URL: https://github.com/jserv/full-stack-hello
- Owner: jserv
- License: other
- Created: 2017-05-23T17:07:01.000Z (about 8 years ago)
- Default Branch: master
- Last Pushed: 2020-12-28T14:42:53.000Z (over 4 years ago)
- Last Synced: 2025-04-14T03:52:46.113Z (about 2 months ago)
- Language: C
- Size: 75.2 KB
- Stars: 115
- Watchers: 11
- Forks: 51
- Open Issues: 6
-
Metadata Files:
- Readme: README.md
- License: LICENSE
- Authors: AUTHORS
Awesome Lists containing this project
- AwesomeCompiler - full-stack-hello
README
# full-stack-hello
`full-stack-hello` is a minimal virtual machine kit capable of performing
tasks at any level of the technical stack on which a typical 'Hello World'
program execution depends. It means:
* Instruction Set Architecture (ISA);
* Virtual machine implementing the ISA;
* Assembly and/or Compiler following the ISA;
* Runtime support such as standard libraries and ELF;
## Instruction set
| Opcode | Description |
| ------------- | ------------- |
| OP_ADD | sum two operands |
| OP_SUB | subtract two operands |
| OP_MUL | multiply two operands |
| OP_DIV | divide two two operands |
| OP_MOD | Modulo, remainder of operand 1 divided by operand 2 |
| OP_PRINT | print integer or string |
| OP_JLT | jump to specified address (in operand 2) if operand 1 is less than 0 |
| OP_JLE | jump to specified address (in operand 2) if operand 1 is less than or equal to 0 |
| OP_JZ | jump to specified address (in operand 2) if operand 1 is equal to 0 |
| OP_JGE | jump to specified address (in operand 2) if operand 1 is greater than or equal to 0 |
| OP_JGT | jump to specified address (in operand 2) if operand 1 is greater than 0 |
| OP_JNZ | jump to specified address (in operand 2) if operand 1 is not equal to 0 |
| OP_JMP | jump to specified address |
| OP_CALL | call to specified address |
| OP_RET | return to where called from |
| OP_HALT | terminate VM |
## Assembly Notation
* Registers are specified by `#` as temporary storage.
* `print #1` dumps the content of register `#1`.
* An immediate value (or simply an immediate or imm) is a piece of data that
is stored as part of the instruction itself instead of being in a memory
location or a register.
* `mul $-2 $2 #4` stores the result of `(-2) * (2)` into register `#4`.
* A valid Label name ends with `:` and is referred as `:X` in any JMP/CALL
instructions to jump to label `X`.
```
A:
print $1
jmp :A
```
* Infinite loop that dumps constant `1`.
## Build and Verify
```shell
$ make
cc -Wall -std=gnu99 -g -c -o vm.o -MMD -MF .vm.o.d vm.c
cc -Wall -std=gnu99 -g -c -o as.o -MMD -MF .as.o.d as.c
cc -Wall -std=gnu99 -g -c -o driver.o -MMD -MF .driver.o.d driver.c
cc -Wall -std=gnu99 -g -o as_exec vm.o as.o driver.o
$ make check
42
tests/halt.s pass
Hello World
tests/hello.s pass
42
50
150
tests/test.s pass
$ make test
python tests/run_tests.py
..
----------------------------------------------------------------------
Ran 4 tests in 0.002s
OK
```
## Assembler Usage
Specify -h to obtain the description of the assembler.
```
$ ./as_exec -h
Usage: as_exec [-w] [-x] [-o ]
-w Assemble and write to an ELF file, see -o below
-o if -w is specifed, is used to store the object code
-x Load and execute it
the file name to be used by commands above
```
For example, if the assembly file in concern is tests/coverage.s
1. Assemble an assembly source file and evaluate (execute) it.
```
./as_exec tests/hello.s
```
2. Assemble an assembly source file and write to default ELF file tests/hello.o.
```
./as_exec -w tests/hello.s
```
3. Assemble an assembly source file and write to default ELF file tests/temp.o.
```
./as_exec -o tests/temp.o -w tests/hello.s
```
4. Laod an assembled ELF file tests/hello.o and evaluate (rexcute) it.
```
./as_exec -x tests/hello.o
```
The common ELF tools, such as objdump, can be applied to the output ELF file.
```
objdump -x tests/hello.o
```
Currently, the ELF support is very limited and could be improved.
## Licensing
`full-stack-hello` is freely redistributable under the two-clause BSD License.
Use of this source code is governed by a BSD-style license that can be found
in the `LICENSE` file.