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commit 63a03d0f8aebd9394d76b9c747c90f72f460ddcb Author: Alan Carvalho de Assis <[email protected]> AuthorDate: Fri May 1 09:00:26 2026 -0300 arch/x86: Add palette 256 color to qemu-i486 VGA driver This patch adds support to get the VGA driver working with 256 colors. Signed-off-by: Alan C. Assis <[email protected]> --- arch/x86/src/qemu/qemu_vga.c | 60 ++++++++++++++++++++++++++++++-------------- 1 file changed, 41 insertions(+), 19 deletions(-) diff --git a/arch/x86/src/qemu/qemu_vga.c b/arch/x86/src/qemu/qemu_vga.c index 4e80a7818ac..8ac021b14a1 100644 --- a/arch/x86/src/qemu/qemu_vga.c +++ b/arch/x86/src/qemu/qemu_vga.c @@ -204,9 +204,6 @@ static const uint8_t height_600[] = 0x70, 0xf0, 0x60, 0x5b, 0x8c, 0x57, 0x58, 0x70 }; -static const uint8_t g_bg_color = 0x0f; -static const uint8_t g_fg_color = 0x01; - static uint8_t g_runbuffer[VGA_XRES]; static uint8_t *g_pscreen = (uint8_t *)(0xa0000); @@ -238,6 +235,43 @@ static const struct file_operations g_vgaops = * Private Functions ****************************************************************************/ +static void vga_init_palette(void) +{ + uint8_t r3; + uint8_t g3; + uint8_t b2; + + static const uint8_t r_levels[8] = + { + 0, 9, 18, 27, 36, 45, 54, 63 + }; + + static const uint8_t g_levels[8] = + { + 0, 9, 18, 27, 36, 45, 54, 63 + }; + + static const uint8_t b_levels[4] = + { + 0, 21, 42, 63 + }; + + outb(0x00, 0x3c8); + + for (r3 = 0; r3 < 8; r3++) + { + for (g3 = 0; g3 < 8; g3++) + { + for (b2 = 0; b2 < 4; b2++) + { + outb(r_levels[r3], 0x3c9); + outb(g_levels[g3], 0x3c9); + outb(b_levels[b2], 0x3c9); + } + } + } +} + /* The chain4 parameter should be 1 for normal 13h-type mode, but * only allows 320x200 256x200, 256x240 and 256x256 because you * can only access the first 64kb @@ -388,19 +422,9 @@ static int init_graph_vga(int width, int height, int chain4) outw(0x4005, 0x3ce); /* 256 color mode */ outw(0x0106, 0x3ce); /* Extend graph mode & a000-bfff */ - inb(0x3da); - outb(0x30, 0x3c0); - outb(0x41, 0x3c0); - outb(0x33, 0x3c0); - outb(0x00, 0x3c0); - - for (a = 0; a < 16; a++) /* ega pal */ - { - outb((uint8_t)a, 0x3c0); - outb((uint8_t)a, 0x3c0); - } + /* Setup the palette to RGB332 used by NuttX, LVGL, etc */ - outb(0x20, 0x3c0); /* enable video */ + vga_init_palette(); return 0; } @@ -476,16 +500,15 @@ static ssize_t vga_write(struct file *filep, const char *buf, size_t buflen) { int i; - int j; if (buf == NULL || buflen < 1) { return -EINVAL; } - for (j = 0; j < buflen && g_curpos < VGA_FBSIZE; j++) + for (i = 0; i < buflen && g_curpos < VGA_FBSIZE; i++) { - g_pscreen[g_curpos++] = (uint8_t)buf[j]; + g_pscreen[g_curpos++] = (uint8_t)buf[i]; } return buflen; @@ -565,7 +588,6 @@ int qemu_vga(void) return ret; } - memset(g_pscreen, g_bg_color, VGA_XRES * VGA_YRES); register_driver("/dev/lcd", &g_vgaops, 0666, NULL); return OK;
