kern: dev: Add video RAM driver

Signed-off-by: Ian Moffett <ian@osmora.org>

3 files changed, 119 insertions, 0 deletions

diff --git a/sys/dev/video/vram.c b/sys/dev/video/vram.c
new file mode 100644
index 0000000..bc85f32
--- /dev/null
+++ b/sys/dev/video/vram.c
@@ -0,0 +1,55 @@
+/*
+ * Copyright (c) 2025 Ian Marco Moffett and the Osmora Team.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of Hyra nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <sys/errno.h>
+#include <sys/types.h>
+#include <dev/video/vram.h>
+#include <lib/limine.h>
+
+#define FRAMEBUFFER \
+        framebuffer_req.response->framebuffers[0]
+
+static volatile struct limine_framebuffer_request framebuffer_req = {
+    .id = LIMINE_FRAMEBUFFER_REQUEST,
+    .revision = 0
+};
+
+int
+vram_getdev(struct vram_dev *result)
+{
+    if (result == NULL) {
+        return -EINVAL;
+    }
+
+    result->io = FRAMEBUFFER->address;
+    result->width = FRAMEBUFFER->width;
+    result->height = FRAMEBUFFER->height;
+    result->pitch = FRAMEBUFFER->pitch;
+    return 0;
+}
diff --git a/sys/inc/dev/video/vram.h b/sys/inc/dev/video/vram.h
new file mode 100644
index 0000000..318329f
--- /dev/null
+++ b/sys/inc/dev/video/vram.h
@@ -0,0 +1,63 @@
+/*
+ * Copyright (c) 2025 Ian Marco Moffett and the Osmora Team.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of Hyra nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef _VIDEO_VRAM_H_
+#define _VIDEO_VRAM_H_ 1
+
+#include <sys/cdefs.h>
+#include <sys/types.h>
+
+/*
+ * Video RAM descriptor, contains information needed
+ * to draw pixels onto the screen.
+ */
+struct vram_dev {
+    uint32_t *io;
+    size_t width;
+    size_t height;
+    size_t pitch;
+};
+
+/*
+ * Acquire a vram descriptor of the vram device
+ * currently in-use.
+ */
+int vram_getdev(struct vram_dev *result);
+
+/*
+ * Acquire the index of a pixel at a given set of
+ * x,y coordinates in cartesian units.
+ */
+__always_inline static size_t
+vram_index(struct vram_dev *vdp, size_t x, size_t y)
+{
+    return x + y * (vdp->pitch / 4);
+}
+
+#endif  /* !_VIDEO_FRAME_*/
diff --git a/sys/kern/Makefile b/sys/kern/Makefile
index 39260ca..b04e252 100644
--- a/sys/kern/Makefile
+++ b/sys/kern/Makefile
@@ -5,6 +5,7 @@ CFILES = $(shell find . -name "*.c")
 CFILES += $(shell find ../lib -name "*.c")
 CFILES += $(shell find ../os -name "*.c")
 CFILES += $(shell find ../vm -name "*.c")
+CFILES += $(shell find ../dev -name "*.c")
 OFILES = $(CFILES:.c=.o)
 DFILES = $(CFILES:.c=.d)
 CC =