From ae5f4001c351b24a7f4e1bee6d995e4cb3cced2f Mon Sep 17 00:00:00 2001 From: Olivier Gayot Date: Fri, 9 Oct 2015 16:01:32 +0200 Subject: kfs: implemented the onscreen printing system the function is prototyped this way: int printk(const char *string); the code has not been tested yet Signed-off-by: Olivier Gayot --- kernel.c | 43 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 43 insertions(+) create mode 100644 kernel.c diff --git a/kernel.c b/kernel.c new file mode 100644 index 0000000..8e59664 --- /dev/null +++ b/kernel.c @@ -0,0 +1,43 @@ +#define NB_COLS 80 +#define NB_ROWS 25 + +/* XXX doest not always handle memory overlaps */ +static void my_memmove(void *dest, const void *src, size_t n) +{ + for (size_t i = 0; i < n; ++i) { + dest[i] = src[i]; + } +} + +static void my_memset(void *dest, int c, size_t n) +{ + for (size_t i = 0; i < n; ++i) { + dest[i] = c; + } +} + +int printk(const char *str) +{ + static char *offset = (char *) 0xb8000; + static char *addr = offset; + int count = 0; + + for (int i = 0; str[i]; ++i) { + if ((long)addr >= 0xb8000 + NB_COLS * NB_ROWS) { + /* shift up */ + addr -= NB_COLS; + my_memmove(offset, offset + NB_COLS, NB_COLS * (NB_ROWS - 1)); + my_memset(offset + NB_COLS * (NB_ROWS - 1), ' ', NB_ROWS); + } + + *addr++ = str[i] + ++count; + + } + + return count; +} + +int main(void) +{ +} -- cgit v1.2.3