From a4eef728064cfc3f14396d0ad91f105f12ef32ea Mon Sep 17 00:00:00 2001
From: Jacob McDonnell <jacob@jacobmcdonnell.com>
Date: Sun, 8 Jun 2025 15:03:33 -0400
Subject: Initial Commit

---
 source/LimineRequests.c | 45 +++++++++++++++++++++++++++++++++++++++++++
 source/LimineRequests.h | 15 +++++++++++++++
 source/main.c           | 51 +++++++++++++++++++++++++++++++++++++++++++++++++
 source/memory.c         | 48 ++++++++++++++++++++++++++++++++++++++++++++++
 source/memory.h         | 12 ++++++++++++
 5 files changed, 171 insertions(+)
 create mode 100644 source/LimineRequests.c
 create mode 100644 source/LimineRequests.h
 create mode 100644 source/main.c
 create mode 100644 source/memory.c
 create mode 100644 source/memory.h

(limited to 'source')

diff --git a/source/LimineRequests.c b/source/LimineRequests.c
new file mode 100644
index 0000000..a3b9bd5
--- /dev/null
+++ b/source/LimineRequests.c
@@ -0,0 +1,45 @@
+#include <stdint.h>
+#include <limine.h>
+#include "LimineRequests.h"
+
+__attribute__((used, section(".limine_requests_start")))
+LIMINE_REQUESTS_START_MARKER
+
+__attribute__((used, section(".limine_requests")))
+static volatile LIMINE_BASE_REVISION(3)
+
+bool VerifyBaseRevision(void) {
+    return (limine_base_revision[2] == 0);
+}
+
+__attribute__((used, section(".limine_requests")))
+struct limine_stack_size_request stackSizeRequest = {
+    LIMINE_STACK_SIZE_REQUEST,
+    0,
+    nullptr,
+    //0xFFFF
+    0x100000
+};
+
+bool VerifyStackSizeRequest(void) {
+    return ((stackSizeRequest.response != nullptr) &&
+            (stackSizeRequest.response->revision >= stackSizeRequest.revision));
+}
+
+__attribute__((used, section(".limine_requests")))
+struct limine_framebuffer_request framebufferRequest = {
+    LIMINE_FRAMEBUFFER_REQUEST,
+    0,
+    nullptr
+};
+
+bool VerifyFramebufferRequest(void) {
+    return ((framebufferRequest.response != nullptr) &&
+            (framebufferRequest.response->framebuffer_count > 0) &&
+            (framebufferRequest.response->revision >=
+             framebufferRequest.revision));
+}
+
+__attribute__((used, section(".limine_requests_end")))
+LIMINE_REQUESTS_END_MARKER
+
diff --git a/source/LimineRequests.h b/source/LimineRequests.h
new file mode 100644
index 0000000..45da613
--- /dev/null
+++ b/source/LimineRequests.h
@@ -0,0 +1,15 @@
+#ifndef LIMINEREQUESTS_H_
+#define LIMINEREQUESTS_H_
+
+#include <stdint.h>
+#include <limine.h>
+
+extern struct limine_stack_size_request stackSizeRequest;
+extern struct limine_framebuffer_request framebufferRequest;
+
+bool VerifyBaseRevision(void);
+bool VerifyStackSizeRequest(void);
+bool VerifyFramebufferRequest(void);
+
+#endif  // LIMINEREQUESTS_H_
+
diff --git a/source/main.c b/source/main.c
new file mode 100644
index 0000000..316274f
--- /dev/null
+++ b/source/main.c
@@ -0,0 +1,51 @@
+#include <stddef.h>
+#include <limine.h>
+#include "LimineRequests.h"
+#include "memory.h"
+
+static void HaltForever(void) {
+    while (true) {
+        asm("hlt");
+    }
+}
+
+void KernelMain(void) {
+    if (!VerifyBaseRevision()) {
+        HaltForever();
+    }
+
+    if (!VerifyStackSizeRequest()) {
+        HaltForever();
+    }
+
+    if (!VerifyFramebufferRequest()) {
+        HaltForever();
+    }
+
+    const uint64_t framebufferCount =
+        framebufferRequest.response->framebuffer_count;
+
+    struct limine_framebuffer **framebuffers =
+        framebufferRequest.response->framebuffers;
+
+    struct limine_framebuffer *framebuffer = nullptr;
+
+    const uint32_t colors[] = {0xFF0000, 0x00FF00, 0x0000FF};
+    uint8_t count = 0;
+    uint8_t color = 0;
+
+    for (uint64_t i = 0; i < framebufferCount; i++) {
+        framebuffer = framebuffers[i];
+        volatile uint32_t *fb_ptr = (volatile uint32_t *)framebuffer->address;
+        for (uint64_t j = 0; j < framebuffer->height && j < framebuffer->width;
+                j++) {
+            fb_ptr[j * (framebuffer->pitch / 4) + j] = colors[color];
+            if ((count = (count + 1) % 16) == 0) {
+                color = (color + 1) % 3;
+            }
+        }
+    }
+
+    HaltForever();
+}
+
diff --git a/source/memory.c b/source/memory.c
new file mode 100644
index 0000000..b9d0405
--- /dev/null
+++ b/source/memory.c
@@ -0,0 +1,48 @@
+#include <stdint.h>
+#include "memory.h"
+
+void *memcpy(void *dest, const void *src, const size_t n) {
+    uint8_t *destB = (void *)dest;
+    const uint8_t *srcB = (void *)src;
+
+    for (size_t i = 0; i < n; i++) {
+        destB[i] = srcB[i];
+    }
+
+    return dest;
+}
+
+void *memset(void *s, int c, size_t n) {
+    uint8_t *sB = (uint8_t *)s;
+
+    for (size_t i = 0; i < n; i++) {
+        sB[i] = (uint8_t)c;
+    }
+
+    return s;
+}
+
+void *memmove(void *dest, const void *src, const size_t n) {
+    uint8_t *db = (uint8_t *)dest;
+    const uint8_t *sb = (const uint8_t *)src;
+
+    for (size_t i = n; i > 0; i--) {
+        db[i - 1] = sb[i - 1];
+    }
+
+    return dest;
+}
+
+int memcmp(const void *s1, const void *s2, const size_t n) {
+    const uint8_t *s1b = (const uint8_t *)s1;
+    const uint8_t *s2b = (const uint8_t *)s2;
+
+    for (size_t i = 0; i < n; i++) {
+        if (s1b[i] != s2b[i]) {
+            return ((s1b[i] > s2b[i]) ? 1 : -1);
+        }
+    }
+
+    return 0;
+}
+
diff --git a/source/memory.h b/source/memory.h
new file mode 100644
index 0000000..0404144
--- /dev/null
+++ b/source/memory.h
@@ -0,0 +1,12 @@
+#ifndef MEMORY_H_
+#define MEMORY_H_
+
+#include <stddef.h>
+
+void *memcpy(void *dest, const void *src, const size_t n);
+void *memset(void *s, int c, size_t n);
+void *memmove(void *dest, const void *src, const size_t n);
+int memcmp(const void *s1, const void *s2, const size_t n);
+
+#endif  // MEMORY_H_
+
-- 
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