diff options
Diffstat (limited to 'README.md')
| -rw-r--r-- | README.md | 39 |
1 files changed, 27 insertions, 12 deletions
@@ -195,11 +195,19 @@ void main(void) { ### libc -`writes`, `putc`, `puts`, `nl`, `strlen`, `readc` (returns `EOF`=4 at end of -input), `getargs` (this program's argument string), `getpid`, `sexit`. +Syscall wrappers (`c/libc.s`): `writes`, `putc`, `puts`, `nl`, `strlen`, `readc` +(returns `EOF`=4 at end of input), `getargs` (this program's argument string), +`getpid`, `sexit`. C helpers (`c/libc.c`, linked into every program): `putu` +(print decimal), `atou` (parse decimal), `argv_parse` (tokenize into argc/argv). + Arguments: the shell splits the command line at the first space and leaves -`"cmd\0args\0"` at `$A000`; the child inherits it through `fork`, and -`getargs()` returns the args. +`"cmd\0args\0"` at `$A000`; the child inherits it through `fork`, `getargs()` +returns the raw arg string, and `argv_parse()` tokenizes it: + +```c +char *argv[8]; +unsigned char argc = argv_parse(argv, 8); /* args one two -> argc=3 */ +``` ### CLI tools (in `c/`) @@ -207,21 +215,27 @@ Arguments: the shell splits the command line at the first space and leaves |------|--------------| | `echo` | print its arguments (`echo hello world`) | | `cat` | copy stdin to stdout until EOF (Ctrl-D / pipe end) | +| `wc` | count lines / words / chars of stdin | +| `head` | print the first *n* lines of stdin (`head 5`, default 10) | +| `args` | argc/argv demo (`args one two three`) | | `uname`| print the system name | | `pid` | print the process's pid (decimal) | | `true` / `false` | exit 0 / 1 | | `chello` | the C "hello" demo | ``` -$ uname -gbos sm83 (Game Boy Color) $ echo C tools on a Game Boy C tools on a Game Boy -$ pid -5 -$ cat -hi from cat -hi from cat +$ args one two three +argc=3 +argv[0]=one +argv[1]=two +argv[2]=three +$ wc (input: "hello world\nfoo\n") +2 3 16 +$ head 2 (input: alpha/beta/gamma/delta) +alpha +beta ``` Each tool is a separate `c/<name>.c`, built to a ROM-bank blob, INCBIN'd, and @@ -244,7 +258,8 @@ explicit lengths and emit newlines via `nl()`. - [x] grow libc (`puts`/`putc`/`strlen`/`getargs`/EOF) + args via the shell - [x] CLI tools in C: `echo`, `cat`, `uname`, `pid`, `true`, `false` - [x] Makefile builds all C programs (a `CBLOBS` list) -- [ ] more tools (`wc`, `head`, `rev`), a real `argc/argv`, a RAM filesystem +- [x] `wc`, `head`, and an `argc/argv` demo (`args`) + `argv_parse` in libc +- [ ] more tools (`rev`, `grep`), option parsing (`-n`), a RAM filesystem - [ ] Preemptive scheduling: real context save in `TimerISR` → `hSwitchTo` - [ ] Use the `$D000-$DFFF` u-area (SVBK) for per-process kernel state / kstack - [ ] `brk`/heap allocator inside the task bank (heap up, stack down, collision = ENOMEM) |