cleanup

yhzhang0128 · Apr 24, 2022 · 2c48fcf · 2c48fcf
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diff --git a/README.md b/README.md
@@ -16,12 +16,12 @@ github.com/AlDanial/cloc v 1.92  T=0.03 s (1668.0 files/s, 105414.7 lines/s)
 -------------------------------------------------------------------------------
 Language                     files          blank        comment           code
 -------------------------------------------------------------------------------
-C                               35            454            486           1566
-C/C++ Header                    11             75            105            312
+C                               35            454            490           1565
+C/C++ Header                    11             74            105            313
 Assembly                         3              6             24             68
 make                             1             11              0             54
 -------------------------------------------------------------------------------
-SUM:                            50            546            615           2000 << exactly 2000!
+SUM:                            50            545            619           2000 << exactly 2000!
 -------------------------------------------------------------------------------
 ```
 

diff --git a/apps/user/cd.c b/apps/user/cd.c
@@ -28,7 +28,7 @@ int main(int argc, char** argv) {
     grass->workdir_ino = dir_ino;
 
     /* Get the path name of the new working directory */
-    if (!strcmp(".", argv[1])) return 0;
+    if (!strcmp("./", argv[1])) return 0;
 
     int len = strlen(grass->workdir);
     if (strcmp("../", argv[1])) {

diff --git a/earth/bus_gpio.c b/earth/bus_gpio.c
@@ -3,7 +3,8 @@
  * All rights reserved.
  */
 
-/* definitions for controlling GPIO0 in FE310
+/* Author: Yunhao Zhang
+ * Description: definitions for controlling GPIO0 in FE310;
  * see chapter17 of the SiFive FE310-G002 Manual
  */
 

diff --git a/earth/bus_uart.c b/earth/bus_uart.c
@@ -3,7 +3,8 @@
  * All rights reserved.
  */
 
-/* definitions for controlling UART0 in FE310
+/* Author: Yunhao Zhang
+ * Description: definitions for controlling UART0 in FE310;
  * see chapter18 of the SiFive FE310-G002 Manual
  */
 

diff --git a/earth/earth.c b/earth/earth.c
@@ -4,7 +4,8 @@
  */
 
 /* Author: Yunhao Zhang
- * Description: Initialize dev_tty, dev_disk, cpu_intr and cpu_mmu;
+ * Description: Initialize the bss and data segments;
+ * Initialize dev_tty, dev_disk, cpu_intr and cpu_mmu;
  * Load the grass layer binary from disk and run it.
  */
 

diff --git a/earth/sd/sd_init.c b/earth/sd/sd_init.c
@@ -1,5 +1,5 @@
 /*
- * (C) 2021, Cornell University
+ * (C) 2022, Cornell University
  * All rights reserved.
  */
 

diff --git a/earth/sd/sd_rw.c b/earth/sd/sd_rw.c
@@ -1,5 +1,5 @@
 /*
- * (C) 2021, Cornell University
+ * (C) 2022, Cornell University
  * All rights reserved.
  */
 

diff --git a/earth/sd/sd_utils.c b/earth/sd/sd_utils.c
@@ -1,5 +1,5 @@
 /*
- * (C) 2021, Cornell University
+ * (C) 2022, Cornell University
  * All rights reserved.
  */
 

diff --git a/grass/grass.c b/grass/grass.c
@@ -4,7 +4,7 @@
  */
 
 /* Author: Yunhao Zhang
- * Description: Initialize the timer and the process control block; 
+ * Description: Initialize timer and the process control block; 
  * Spawn the first kernel process, GPID_PROCESS (pid=1).
  */
 

diff --git a/grass/timer.c b/grass/timer.c
@@ -4,9 +4,9 @@
  */
 
 /* Author: Yunhao Zhang
- * Description: Initialize and reset the timer;
- * See section 3.1.15 of the RISC-V manual, volume2, v1.10
- * and section 9.1, 9.3 of the Sifive FE310 manual, v19p04.
+ * Description: Initialize and reset timer;
+ * see section 3.1.15 of the RISC-V manual, volume2, v1.10
+ * and section 9.1, 9.3 of the Sifive FE310 manual, v19p04
  */
 
 #include "egos.h"

diff --git a/library/file/block_store.h b/library/file/block_store.h
@@ -1,4 +1,3 @@
-#pragma once
 /*
  * (C) 2017, Cornell University
  * All rights reserved.
@@ -39,6 +38,7 @@
  * state the block store module needs to keep.
  */
 
+#pragma once
 #include "disk.h"
 
 #define NINODES  128

diff --git a/library/file/file.h b/library/file/file.h
@@ -30,7 +30,7 @@
  * the list, or otherwise a pointer to the next block on the list.  The
  * remaining slots point to free blocks, or 0 if the slot is empty.
  */
-
+#pragma once
 #include "block_store.h"
 
 #define INODES_PER_BLOCK  (BLOCK_SIZE / sizeof(struct treedisk_inode))

diff --git a/library/libc/malloc.c b/library/libc/malloc.c
@@ -19,7 +19,7 @@ static char* brk = &__heap_start;
 char *_sbrk(int size) {
     if ((brk + size) > (&__heap_end)) {
         earth->tty_write("_sbrk: heap grows too large\r\n", 29);
-        *(int*)(0x1000) = 1; /* Trigger a memory exception */
+        *(int*)(0x1000) = 1;    /* Trigger a memory exception */
     }
 
     char *old_brk = brk;

diff --git a/library/libc/print.c b/library/libc/print.c
@@ -11,7 +11,7 @@
 #include <unistd.h>
 
 /* printf() constructs a string based on its arguments 
- * and then print this string to tty by calling _write() 
+ * and then print the string to tty by calling _write() 
  */
 
 int _write(int file, char *ptr, int len) {

diff --git a/library/servers/servers.c b/library/servers/servers.c
@@ -4,7 +4,7 @@
  */
 
 /* Author: Yunhao Zhang
- * Description: user friendly interfaces of the servers
+ * Description: user friendly interfaces of the system servers
  */
 
 #include "egos.h"

diff --git a/references/README.md b/references/README.md
@@ -10,7 +10,7 @@ There are five mandatory projects:
 | P0 | Queue                           | memory, pointer, instruction and stack pointers             | Linux/Mac  |
 | P1 | User-level threading            | thread, context switch, synchronization                     | Linux/Mac  |
 | P2 | Multi-level feedback queue      | timer and quantum, scheduling, priority                     | Linux/Mac  |
-| P3 | Memory management               | control register, exception handling, privilege level       | Arty board |
+| P3 | Memory protection and exception | control register, exception handling, privilege level       | Arty board |
 | P5 | File system                     | inode layer, directory layer, layered file system           | Arty board |
 
 And some optional projects:
@@ -22,67 +22,67 @@ And some optional projects:
 ## Architecture
 
 **Earth layer (hardware specific)**
-* `earth/dev_disk`: SD card (touched by P4)
+* `earth/dev_disk`: ROM and SD card (touched by P4)
 * `earth/dev_tty`: keyboard input and tty output
 * `earth/cpu_intr`: interrupt and exception handling (touched by P3)
 * `earth/cpu_mmu`: memory paging and address translation (touched by P3)
 
 **Grass layer (hardware independent)**
-* `grass/timer`: control timer registers
+* `grass/timer`: timer control registers
 * `grass/syscall`: system call interfaces to user applications
-* `grass/process`: manage process data structures (touched by P1)
+* `grass/process`: data structures for managing processes (touched by P1)
 * `grass/scheduler`: preemptive scheduling and inter-process communication (touched by P2)
 
 **Application layer**
-* `app/system/sys_proc`: manage allocation and free of user processes
-* `app/system/sys_file`: manage an inode layer on the SD card (touched by P5)
-* `app/system/sys_dir`: manage the directory layer on top of inode layer (touched by P5)
+* `app/system/sys_proc`: allocation and free of user processes
+* `app/system/sys_file`: the inode layer over the SD card (touched by P5)
+* `app/system/sys_dir`: the directory layer over the inode layer (touched by P5)
 * `app/system/sys_shell`: interactive user interface
-* user commands: `pwd`, `clear`, `killall`, `ls`, `cat`, `echo`, `clock`
+* user commands: `pwd`, `cd`, `ls`, `cat`, `echo`, `clock`, `killall`
 
 Every layer has dedicated memory regions as described below (and in `library/egos.h`).
-The complete memory layout is described in Chapter 4 of the FE310 manual in this repository.
+The complete memory layout is described in Chapter 4 of the [FE310 manual](sifive-fe310-v19p04.pdf).
 
 **Selected RAM regions**
 
 | Base        | Top         | Attributes | Description       | Notes                                                      |
 |-------------|-------------|------------|-------------------|------------------------------------------------------------|
 | 0x0800_0000 | 0x0800_2FFF | RWX A      | ITIM, 12KB        | Earth layer bss, data and heap                             |
 | 0x0800_3000 | 0x0800_4FFF | RWX A      | ITIM, 8KB         | Grass layer code, bss, data and heap                       |
-| 0x0800_5000 | 0x0800_7FFF | RWX A      | ITIM, 12KB        | App code, bss, data and heap                               |
+| 0x0800_5000 | 0x0800_7FFF | RWX A      | ITIM, 12KB        | App layer code, bss, data and heap                         |
 | ......      | ......      | ......     | ......            |                                                            |
 | 0x2000_0000 | 0x203F_FFFF | R XC       | Flash ROM, 4MB    | FPGA binary of the FE310 RISC-V processor                  |
-| 0x2040_0000 | 0x207F_FFFF | R XC       | Flash ROM, 4MB    | Earth layer code and rodata                                |
+| 0x2040_0000 | 0x207F_FFFF | R XC       | Flash ROM, 4MB    | Earth layer binary                                         |
 | 0x2080_0000 | 0x20BF_FFFF | R XC       | Flash ROM, 4MB    | Disk image (disk.img produced by mkrom)                    |
 | ......      | ......      | ......     | ......            |                                                            |
-| 0x8000_0000 | 0x8000_1FFF | RW- A      | DTIM, 8KB         | App stack                                                  |
-| 0x8000_2000 | 0x8000_3FFF | RW- A      | DTIM, 8KB         | Earth and grass stack                                      |
+| 0x8000_0000 | 0x8000_1FFF | RW- A      | DTIM, 8KB         | App layer stack                                            |
+| 0x8000_2000 | 0x8000_3FFF | RW- A      | DTIM, 8KB         | Earth layer and grass layer stack                          |
 | 0x8000_4000 | 0x8001_FFFF | RW- A      | DTIM, 112KB       | MMU cache of physical frames for suspended grass processes |
 
-The first 1MB of the microSD card is used as 256 physical frames by the MMU for paging.
+The first 1MB of the microSD card is used as 256 physical frames by the MMU for paging (see `earth/cpu_mmu.c`).
 
 **Selected memory-mapped I/O regions**
 
-| Base        | Top         | Attributes | Description   | Notes                                 |
-|-------------|-------------|------------|---------------|---------------------------------------|
-| 0x1001_4000 | 0x1001_4FFF | RW A       | QSPI 0        | Control the 16MB on-board flash ROM   |
-| 0x1002_4000 | 0x1002_4FFF | RW A       | SPI 1         | Control the Pmod1 (microSD card) pins |
+| Base        | Top         | Attributes | Description   | Notes                            |
+|-------------|-------------|------------|---------------|----------------------------------|
+| 0x1001_4000 | 0x1001_4FFF | RW A       | QSPI 0        | Control the 16MB on-board ROM    |
+| 0x1002_4000 | 0x1002_4FFF | RW A       | SPI 1         | Control the Pmod1 (microSD card) |
 
 ## Software development history
 
 **Iteration #6**
 
-* [2022.04] Add a simple boot loader `earth/earth.S`; Remove dependency on the Freedom Metal library
-* [2022.04] Add `_write()` and `_sbrk()` in `library/libc`; Remove the Freedom Metal library entirely
+* [2022.04] Add a simple boot loader `earth/earth.S`; Remove dependency on the Metal library
+* [2022.04] Add `_write()` and `_sbrk()` in `library/libc`; Remove the Metal library entirely
 * [2022.04] Enrich `struct grass` in order to improve clarity of the architecture
-* [2022.04] Experiment with RISC-V Physical Memory Protection (PMP) and memory exception handling
+* [2022.04] Experiment with Physical Memory Protection (PMP) and switching privilege level (machine <-> user)
 
 **Iteration #5**
 
 * [2022.03] Implement system calls and 4 shell commands: `pwd`, `ls`, `cat` and `echo`
 * [2022.03] Add support of background shell commands and `killall`
 * [2022.03] Add servers in `library` and cleanup access to the file system
-* [2022.03] Cleanup the code controlling UART and SPI; Remove dependency on the Freedom Metal library
+* [2022.03] Cleanup the code controlling UART and SPI; Remove dependency on the Metal library
 
 **Iteration #4**
 * [2022.02] Read Chapter 1, 2 and 3 of [RISC-V manual](riscv-privileged-v1.10.pdf)
@@ -100,14 +100,14 @@ The first 1MB of the microSD card is used as 256 physical frames by the MMU for
 **Iteration #2**
 * Yeah, I didn't work on this project in most of 2021...
 * [2021.12] Create a docker image for portable toolchain setup: [Docker Hub repo](https://hub.docker.com/repository/docker/yhzhang0128/arty-toolchain)
-* [2021.12] Reconnect the processor SPI bus controller to the Arty Pmod1 ports
-* [2021.12] Implement the SD card initialize, read_block and write_block functions
-* [2021.12] Increase the processor clock frequency from 32MHz to 65MHz so that read/write blocks becomes faster
+* [2021.12] Reconnect the processor SPI bus controller to the Arty Pmod1 pins
+* [2021.12] Implement the SD card initialize, read and write functions
+* [2021.12] Increase the processor clock frequency from 32MHz to 65MHz so that read/write blocks become faster
 
 **Iteration #1**
-* [2020.12] Increase the processor memory from 32KB to 160KB (128KB + 32KB)
-* [2020.12] Confirm that the memory cannot be further increased due to the Artix-7 35T limits
+* [2020.12] Increase the processor memory from 24KB to 160KB (128KB + 32KB)
+* [2020.12] Confirm that the memory cannot be further increased due to the limitation of Artix-7 35T FPGA chip
 
 **Iteration #0**
-* [2020.09] Setup the toolchain; Compile and run Hello World on Arty
-* [2020.09] Test the basic input and print functionalities using the Freedom Metal library
+* [2020.09] Setup the toolchain provided by SiFive; Compile and run Hello World on Arty
+* [2020.09] Test the basic input and print functionalities using the SiFive Metal library
diff --git a/tools/mkfs.c b/tools/mkfs.c
@@ -5,10 +5,11 @@
 
 /* Author: Yunhao Zhang
  * Description: create the disk image file (disk.img)
- * the first  1MB is reserved as 256 physical frames for paging
- * the second 1MB contains some ELF binary executables for booting
- * the last   2MB is managed by a file system
- * in total, disk.img should be exactly 4MB
+ * The disk image should be exactly 4MB
+ *     the first 1MB is reserved as 256 frames for memory paging
+ *     the next  1MB contains some ELF binary executables for booting
+ *     the last  2MB is managed by a file system
+ * the output is in binary format (disk.img)
  */
 
 #include <stdio.h>
@@ -71,7 +72,6 @@ int main() {
     write(1, exec, PAGING_DEV_SIZE);
 
     /* grass kernel processes */
-    assert(NKERNEL_PROC <= GRASS_NEXEC);
     int exec_size = GRASS_EXEC_SIZE / GRASS_NEXEC;
     fprintf(stderr, "[INFO] Loading %d kernel binary files\n", NKERNEL_PROC);