feature: add gfrandom driver logic

.clang-format

@@ -0,0 +1,28 @@
+# 小褌懈谢褜 褎芯褉屑邪褌懈褉芯胁邪薪懈褟
+BasedOnStyle: Google
+
+# 袧邪褋褌褉芯泄泻懈 芯褌褋褌褍锌芯胁
+IndentWidth: 4
+TabWidth: 4
+UseTab: Never
+
+# 袪邪蟹褉褘胁褘 褋褌褉芯泻
+ColumnLimit: 100
+BreakBeforeBraces: Allman
+
+# 袩褉芯斜械谢褘
+SpaceBeforeParens: ControlStatements
+SpaceInEmptyParentheses: false
+
+# 袙褘褉邪胁薪懈胁邪薪懈械
+AlignConsecutiveAssignments: true
+AlignConsecutiveDeclarations: true
+
+# 校泻邪蟹邪褌械谢懈 懈 褋褋褘谢泻懈
+PointerAlignment: Left
+
+AllowShortFunctionsOnASingleLine: None
+AllowShortIfStatementsOnASingleLine: false
+
+# 小芯褉褌懈褉芯胁泻邪
+SortIncludes: true

.github/workflows/ci.yml

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+name: Simple driver tests
+
+on: [push, pull_request]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Install dependencies
+        run: sudo apt-get update && sudo apt-get install -y gcc make clang
+
+      - name: Static analysis
+        run: clang-tidy prandom.c Galois_Field_256.c test.c -- -I.
+
+      - name: Build driver
+        run: make
+
+      - name: Build test
+        run: make test_algo
+
+      - name: Run test
+        run: make test
+
+      - name: Run with sanitizers
+        run: make test_sanitized && ./test

.gitignore

@@ -0,0 +1,17 @@
+*.o
+*.ko
+*.mod.c
+*.mod
+*.order
+*.symvers
+ Module.symvers
+.gfrandom.mod.cmd
+gfrandom.mod
+compile_commands.json
+.cache
+*.swp
+*.swo
+*~
+test
+test_gen
+expected_gen

Galois_Field_256.c

@@ -0,0 +1,82 @@
+
+// SPDX-License-Identifier: MIT
+// Copyright (c) 2026 Denis Potapov
+
+#include "Galois_Field_256.h"
+
+#ifdef __KERNEL__
+#include <linux/types.h>
+u16 Module        = 0x11B;
+u8  ready_to_work = 0;
+#else
+#include <stdint.h>
+uint16_t Module        = 0x11B;
+uint8_t  ready_to_work = 0;
+#endif
+
+#define ORDER 256
+
+GF256_t alogs[ORDER];
+GF256_t logs[ORDER];
+
+void GF256_init(void) {
+    // 锌芯褉芯卸写邪褞褖懈泄 褝谢械屑械薪褌 x + 1
+    GF256_t elem = 1;  // (x + 1)**0
+
+    for (int i = 0; i < ORDER - 1; i++) {
+        alogs[i]   = elem;  // <=> (x + 1)**i = elem
+        logs[elem] = i;
+
+        uint16_t new_elem = (uint16_t)elem << 1;  // <=> new_elem = elem * x
+
+        new_elem ^= elem;  // <=> new_elem = elem * x + elem <=> new_elem = elem * (x + 1)
+
+        if (new_elem >= 0x100) {
+            new_elem ^= Module;
+        }
+        elem = (GF256_t)(new_elem);
+    }
+    alogs[ORDER - 1] = alogs[0];
+
+    logs[0] = 0;
+
+    ready_to_work = 1;
+}
+
+GF256_t GF256_Add(GF256_t a, GF256_t b) {
+    return a ^ b;
+}
+
+GF256_t GF256_Sub(GF256_t a, GF256_t b) {
+    return a ^ b;
+}
+
+GF256_t GF256_Mul(GF256_t a, GF256_t b) {
+    if (!ready_to_work) {
+        GF256_init();
+    }
+    if (a == 0 || b == 0) {
+        return 0;
+    }
+
+    uint8_t log_a = logs[a];
+    uint8_t log_b = logs[b];
+
+    uint16_t sum = (log_a + log_b) % (ORDER - 1);
+
+    return alogs[sum];
+}
+
+GF256_t inverse_mul_element(GF256_t a) {
+    if (a == 0) {
+        return 0;
+    }
+    if (!ready_to_work) {
+        GF256_init();
+    }
+    return alogs[255 - logs[a]];
+}
+
+GF256_t GF256_Div(GF256_t a, GF256_t b) {
+    return GF256_Mul(a, inverse_mul_element(b));
+}

Galois_Field_256.h

@@ -0,0 +1,24 @@
+
+// SPDX-License-Identifier: MIT
+// Copyright (c) 2026 Denis Potapov
+
+#ifndef Galois_Field_256
+#define Galois_Field_256
+
+#ifdef __KERNEL__
+#include <linux/types.h>
+typedef u8 GF256_t;
+#else
+#include <stdint.h>
+typedef uint8_t GF256_t;
+#endif
+
+GF256_t GF256_Add(GF256_t a, GF256_t b);
+
+GF256_t GF256_Sub(GF256_t a, GF256_t b);
+
+GF256_t GF256_Mul(GF256_t a, GF256_t b);
+
+GF256_t GF256_Div(GF256_t a, GF256_t b);
+
+#endif

Makefile

@@ -1,11 +1,22 @@
-obj-m += prandom.o
-
-KDIR := /lib/modules/$(shell uname -r)/build
-
-PWD := $(shell pwd)
-
-all:
-	$(MAKE) -C $(KDIR) M=$(PWD) modules
-
-clean:
-	$(MAKE) -C $(KDIR) M=$(PWD) clean
+obj-m += gfrandom.o
+gfrandom-objs := driver.o prandom.o Galois_Field_256.o
+
+KDIR := /lib/modules/$(shell uname -r)/build
+PWD := $(shell pwd)
+
+all:
+	$(MAKE) -C $(KDIR) M=$(PWD) modules
+
+clean:
+	$(MAKE) -C $(KDIR) M=$(PWD) clean
+
+test_algo: test.c Galois_Field_256.c prandom.c
+	gcc -o test test.c Galois_Field_256.c prandom.c
+
+test_sanitized: test.c Galois_Field_256.c prandom.c
+	gcc -o test test.c Galois_Field_256.c prandom.c -fsanitize=address,undefined -g
+
+test: test_algo
+	./test
+
+.PHONY: all clean test test

README.md

@@ -0,0 +1,102 @@
+# prandom
+
+[![CI](https://github.com/estoniec/prandom/actions/workflows/ci.yml/badge.svg)](https://github.com/estoniec/prandom/actions/workflows/ci.yml)
+[![Clang-Tidy](https://img.shields.io/badge/Clang--Tidy-passing-green)](https://clang.llvm.org/docs/ClangFormat.html)
+
+Linux kernel 屑芯写褍谢褜, 锌褉械写芯褋褌邪胁谢褟褞褖懈泄 谐械薪械褉邪褌芯褉 锌褋械胁写芯褋谢褍褔邪泄薪褘褏 褔懈褋械谢 薪邪 芯褋薪芯胁械 锌芯谢械泄 袚邪谢褍邪 (GF(2鈦�)).
+
+## 袨锌懈褋邪薪懈械
+
+袛褉邪泄胁械褉 褋芯蟹写邪褢褌 misc-褍褋褌褉芯泄褋褌胁芯 `/dev/gfrandom`, 泻芯褌芯褉芯械 胁芯蟹胁褉邪褖邪械褌 锌褋械胁写芯褋谢褍褔邪泄薪褘械 斜邪泄褌褘, 褋谐械薪械褉懈褉芯胁邪薪薪褘械 褋 懈褋锌芯谢褜蟹芯胁邪薪懈械屑 邪褉懈褎屑械褌懈泻懈 锌芯谢械泄 袚邪谢褍邪 GF(2鈦�). 携胁谢褟械褌褋褟 邪薪邪谢芯谐芯屑 `/dev/urandom`.
+
+### 袗谢谐芯褉懈褌屑
+
+袠褋锌芯谢褜蟹褍械褌褋褟 褉械谐懈褋褌褉 褋写胁懈谐邪 褋 谢懈薪械泄薪芯泄 芯斜褉邪褌薪芯泄 褋胁褟蟹褜褞 (LFSR) 薪邪写 锌芯谢械屑 GF(2鈦�):
+- 小芯褋褌芯褟薪懈械: 256 斜邪泄褌 (泻芯褝褎褎懈褑懈械薪褌褘)
+- 袧邪褔邪谢褜薪芯械 褋芯褋褌芯褟薪懈械 (seed): t^256 + t^10 + t^5 + t^2 + 1 (懈谢懈 锌芯谢褜蟹芯胁邪褌械谢褜褋泻懈泄)
+- 袚械薪械褉懈褉褍械屑芯械 蟹薪邪褔械薪懈械: 褋褍屑屑邪 锌褉芯懈蟹胁械写械薪懈泄 薪械薪褍谢械胁褘褏 泻芯褝褎褎懈褑懈械薪褌芯胁 褋芯褋褌芯褟薪懈褟 薪邪 褋芯芯褌胁械褌褋褌胁褍褞褖懈械 泻芯褝褎褎懈褑懈械薪褌褘
+
+### 袠褋锌芯谢褜蟹褍械屑褘械 泻芯屑锌芯薪械薪褌褘
+
+- **gfrandom** 鈥� 写褉邪泄胁械褉 (GPL-3.0)
+- **Galois_Field_256** 鈥� [斜懈斜谢懈芯褌械泻邪 写谢褟 褉邪斜芯褌褘 褋 锌芯谢褟屑懈 袚邪谢褍邪](https://github.com/DenisPotapov0/Galua-Field-library) (MIT License)
+
+## 孝褉械斜芯胁邪薪懈褟
+
+- Linux kernel headers (写谢褟 褋斜芯褉泻懈 屑芯写褍谢褟)
+- GCC, make
+- 袛谢褟 蟹邪锌褍褋泻邪 褌械褋褌芯胁: linux-headers 懈谢懈 root 写芯褋褌褍锌 写谢褟 蟹邪谐褉褍蟹泻懈 屑芯写褍谢褟
+
+## 袛械褌械褉屑懈薪懈褉芯胁邪薪薪褘械 褌械褋褌芯胁褘械 写邪薪薪褘械
+
+袛谢褟 褍写芯斜褋褌胁邪 锌芯谢褜蟹芯胁邪褌械谢械泄, 卸械谢邪褞褖懈褏 锌芯谢褍褔懈褌褜 写械褌械褉屑懈薪懈褉芯胁邪薪薪褘械 锌褉械写褋泻邪蟹褍械屑褘械 褔懈褋谢邪, 胁 锌邪锌泻械 `assets` 锌褉械写褋褌邪胁谢械薪褘 褋褌邪薪写邪褉褌薪褘械 斜懈薪邪褉薪褘械 褎邪泄谢褘 锌芯 256 斜邪泄褌 泻邪卸写褘泄:
+- `seed_file.bin` 鈥� 薪邪褔邪谢褜薪芯械 褋芯褋褌芯褟薪懈械 (seed)
+- `coeff_file.bin` 鈥� 泻芯褝褎褎懈褑懈械薪褌褘
+
+协褌懈 卸械 褎邪泄谢褘 懈褋锌芯谢褜蟹褍褞褌褋褟 胁 褌械褋褌邪褏 鈩�1 懈 鈩�2. 袩械褉胁褘械 10 芯卸懈写邪械屑褘褏 褋谢褍褔邪泄薪褘褏 斜邪泄褌芯胁: (HEX: `47 6b 77 79 60 1c bd 3f c9 b2`) 鈥� 褋屑. `assets/expected1.bin`.
+
+## 小斜芯褉泻邪
+
+### Linux 屑芯写褍谢褜
+
+```bash
+make
+```
+
+### Userspace 褌械褋褌褘
+
+```bash
+make test_algo
+./test
+```
+
+## 袠褋锌芯谢褜蟹芯胁邪薪懈械
+
+### 袟邪谐褉褍蟹泻邪 屑芯写褍谢褟
+
+```bash
+sudo insmod gfrandom.ko
+```
+
+### 袩邪褉邪屑械褌褉褘 屑芯写褍谢褟
+
+- `coeff_file` 鈥� 锌褍褌褜 泻 褎邪泄谢褍 褋 泻芯褝褎褎懈褑懈械薪褌邪屑懈 (256 斜邪泄褌)
+- `seed_file` 鈥� 锌褍褌褜 泻 褎邪泄谢褍 褋 seed (256 斜邪泄褌)
+
+袝褋谢懈 锌邪褉邪屑械褌褉褘 薪械 褍泻邪蟹邪薪褘, 懈褋锌芯谢褜蟹褍褞褌褋褟 邪胁褌芯屑邪褌懈褔械褋泻懈 褋谐械薪械褉懈褉芯胁邪薪薪褘械 蟹薪邪褔械薪懈褟.
+
+袩褉懈屑械褉 懈褋锌芯谢褜蟹芯胁邪薪懈褟 褋芯斜褋褌胁械薪薪褘褏 锌邪褉邪屑械褌褉芯胁:
+```bash
+sudo insmod gfrandom.ko coeff_file=/path/to/coeffs.bin seed_file=/path/to/seed.bin
+```
+
+### 效褌械薪懈械 褋谢褍褔邪泄薪褘褏 写邪薪薪褘褏
+
+```bash
+sudo cat /dev/gfrandom | head -c 1024 > /dev/null
+```
+
+### 袙褘谐褉褍蟹泻邪 屑芯写褍谢褟
+
+```bash
+sudo rmmod gfrandom
+```
+
+## 孝械褋褌懈褉芯胁邪薪懈械
+
+孝械褋褌褘 蟹邪锌褍褋泻邪褞褌褋褟 胁 CI 懈 谢芯泻邪谢褜薪芯:
+
+```bash
+make test
+```
+
+## 袥懈褑械薪蟹懈褟
+
+- **gfrandom**: GPL-3.0
+- **Galois_Field_256** (Denis Potapov): MIT License
+
+袩芯写褉芯斜薪芯褋褌懈 褋屑. 胁 [LICENSE](LICENSE).
+
+## 袗胁褌芯褉
+
+袦邪泻邪褉 袥懈谢谢褜

assets/coeff_file.bin

@@ -0,0 +1,2 @@
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assets/expected1.bin

@@ -0,0 +1 @@
+Gkwy`�?刹