make new code like old code

Variable declarations at top of function,
separate from initialization.

Use == 0 instead of ! for checking pointers.

Consistent spacing around {, *, casts.

Declare 0-parameter functions as (void) not ().

Integer valued functions return -1 on failure, 0 on success.

bootmain.c

@@ -33,7 +33,7 @@ bootmain(void)
   // Load each program segment (ignores ph flags).
   ph = (struct proghdr*)((uchar*)elf + elf->phoff);
   eph = ph + elf->phnum;
-  for(; ph < eph; ph++) {
+  for(; ph < eph; ph++){
     va = (uchar*)ph->va;
     readseg(va, ph->filesz, ph->offset);
     if(ph->memsz > ph->filesz)

console.c

@@ -27,15 +27,16 @@ printint(int xx, int base, int sgn)
 {
   static char digits[] = "0123456789abcdef";
   char buf[16];
-  int i = 0, neg = 0;
+  int i, neg;
   uint x;
 
-  if(sgn && xx < 0){
+  if(sgn && (neg = xx < 0)){
     neg = 1;
     x = -xx;
   } else
     x = xx;
 
+  i = 0;
   do{
     buf[i++] = digits[x % base];
   }while((x /= base) != 0);

defs.h

@@ -62,7 +62,7 @@ void            ioapicinit(void);
 // kalloc.c
 char*           kalloc(void);
 void            kfree(char*);
-void            kinit();
+void            kinit(void);
 
 // kbd.c
 void            kbdintr(void);
@@ -117,8 +117,8 @@ void            getcallerpcs(void*, uint*);
 int             holding(struct spinlock*);
 void            initlock(struct spinlock*, char*);
 void            release(struct spinlock*);
-void            pushcli();
-void            popcli();
+void            pushcli(void);
+void            popcli(void);
 
 // string.c
 int             memcmp(const void*, const void*, uint);
@@ -164,7 +164,7 @@ void            inituvm(pde_t*, char*, uint);
 int             loaduvm(pde_t*, char*, struct inode *, uint, uint);
 pde_t*          copyuvm(pde_t*,uint);
 void            switchuvm(struct proc*);
-void            switchkvm();
+void            switchkvm(void);
 int             copyout(pde_t *pgdir, uint va, void *buf, uint len);
 
 // number of elements in fixed-size array

exec.c

@@ -10,45 +10,47 @@ int
 exec(char *path, char **argv)
 {
   char *s, *last;
-  int i, off;
-  uint sz = 0;
+  int i, off, argc;
+  uint sz, sp, strings[MAXARG];
   struct elfhdr elf;
-  struct inode *ip = 0;
+  struct inode *ip;
   struct proghdr ph;
-  pde_t *pgdir = 0, *oldpgdir;
+  pde_t *pgdir, *oldpgdir;
 
   if((ip = namei(path)) == 0)
     return -1;
   ilock(ip);
+  pgdir = 0;
 
   // Check ELF header
   if(readi(ip, (char*)&elf, 0, sizeof(elf)) < sizeof(elf))
     goto bad;
   if(elf.magic != ELF_MAGIC)
     goto bad;
 
-  if(!(pgdir = setupkvm()))
+  if((pgdir = setupkvm()) == 0)
     goto bad;
 
   // Load program into memory.
+  sz = 0;
   for(i=0, off=elf.phoff; i<elf.phnum; i++, off+=sizeof(ph)){
     if(readi(ip, (char*)&ph, off, sizeof(ph)) != sizeof(ph))
       goto bad;
     if(ph.type != ELF_PROG_LOAD)
       continue;
     if(ph.memsz < ph.filesz)
       goto bad;
-    if(!(sz = allocuvm(pgdir, sz, ph.va + ph.memsz)))
+    if((sz = allocuvm(pgdir, sz, ph.va + ph.memsz)) == 0)
       goto bad;
-    if(!loaduvm(pgdir, (char *)ph.va, ip, ph.offset, ph.filesz))
+    if(loaduvm(pgdir, (char*)ph.va, ip, ph.offset, ph.filesz) < 0)
       goto bad;
   }
   iunlockput(ip);
   ip = 0;
 
   // Allocate a one-page stack at the next page boundary
   sz = PGROUNDUP(sz);
-  if(!(sz = allocuvm(pgdir, sz, sz + PGSIZE)))
+  if((sz = allocuvm(pgdir, sz, sz + PGSIZE)) == 0)
     goto bad;
 
   // initialize stack content:
@@ -64,24 +66,22 @@ exec(char *path, char **argv)
   // argc                             -- argc argument to main()
   // ffffffff                         -- return PC for main() call
 
-  uint sp = sz;
+  sp = sz;
 
   // count arguments
-  int argc;
   for(argc = 0; argv[argc]; argc++)
     ;
   if(argc >= MAXARG)
     goto bad;
 
   // push strings and remember where they are
-  uint strings[MAXARG];
   for(i = argc - 1; i >= 0; --i){
     sp -= strlen(argv[i]) + 1;
     strings[i] = sp;
     copyout(pgdir, sp, argv[i], strlen(argv[i]) + 1);
   }
 
-#define PUSH(x) { int xx = (int)(x); sp -= 4; copyout(pgdir, sp, &xx, 4); }
+#define PUSH(x){ int xx = (int)(x); sp -= 4; copyout(pgdir, sp, &xx, 4); }
 
   PUSH(0); // argv[argc] is zero
 

ide.c

@@ -131,7 +131,7 @@ iderw(struct buf *b)
   if((b->flags & (B_VALID|B_DIRTY)) == B_VALID)
     panic("iderw: nothing to do");
   if(b->dev != 0 && !havedisk1)
-    panic("idrw: ide disk 1 not present");
+    panic("iderw: ide disk 1 not present");
 
   acquire(&idelock);
 
@@ -147,7 +147,7 @@ iderw(struct buf *b)
 
   // Wait for request to finish.
   // Assuming will not sleep too long: ignore proc->killed.
-  while((b->flags & (B_VALID|B_DIRTY)) != B_VALID) {
+  while((b->flags & (B_VALID|B_DIRTY)) != B_VALID){
     sleep(b, &idelock);
   }
 

kalloc.c

@@ -23,9 +23,11 @@ extern char end[]; // first address after kernel loaded from ELF file
 void
 kinit(void)
 {
+  char *p;
+
   initlock(&kmem.lock, "kmem");
-  char *p = (char*)PGROUNDUP((uint)end);
-  for( ; p + PGSIZE - 1 < (char*) PHYSTOP; p += PGSIZE)
+  p = (char*)PGROUNDUP((uint)end);
+  for(; p + PGSIZE - 1 < (char*)PHYSTOP; p += PGSIZE)
     kfree(p);
 }
 
@@ -39,14 +41,14 @@ kfree(char *v)
 {
   struct run *r;
 
-  if(((uint) v) % PGSIZE || v < end || (uint)v >= PHYSTOP) 
+  if((uint)v % PGSIZE || v < end || (uint)v >= PHYSTOP) 
     panic("kfree");
 
   // Fill with junk to catch dangling refs.
   memset(v, 1, PGSIZE);
 
   acquire(&kmem.lock);
-  r = (struct run *) v;
+  r = (struct run*)v;
   r->next = kmem.freelist;
   kmem.freelist = r;
   release(&kmem.lock);
@@ -56,7 +58,7 @@ kfree(char *v)
 // Returns a pointer that the kernel can use.
 // Returns 0 if the memory cannot be allocated.
 char*
-kalloc()
+kalloc(void)
 {
   struct run *r;
 
@@ -65,6 +67,6 @@ kalloc()
   if(r)
     kmem.freelist = r->next;
   release(&kmem.lock);
-  return (char*) r;
+  return (char*)r;
 }
 

main.c

@@ -7,7 +7,7 @@
 
 static void bootothers(void);
 static void mpmain(void);
-void jkstack(void)  __attribute__((noreturn));
+void jmpkstack(void)  __attribute__((noreturn));
 void mainc(void);
 
 // Bootstrap processor starts running C code here.
@@ -20,19 +20,20 @@ main(void)
   lapicinit(mpbcpu());
   seginit();       // set up segments
   kinit();         // initialize memory allocator
-  jkstack();       // call mainc() on a properly-allocated stack 
+  jmpkstack();       // call mainc() on a properly-allocated stack 
 }
 
 void
-jkstack(void)
+jmpkstack(void)
 {
-  char *kstack = kalloc();
-  if(!kstack)
-    panic("jkstack\n");
-  char *top = kstack + PGSIZE;
-  asm volatile("movl %0,%%esp" : : "r" (top));
-  asm volatile("call mainc");
-  panic("jkstack");
+  char *kstack, *top;
+
+  kstack = kalloc();
+  if(kstack == 0)
+    panic("jmpkstack kalloc");
+  top = kstack + PGSIZE;
+  asm volatile("movl %0,%%esp; call mainc" : : "r" (top));
+  panic("jmpkstack");
 }
 
 // Set up hardware and software.
@@ -67,7 +68,7 @@ mainc(void)
 static void
 mpmain(void)
 {
-  if(cpunum() != mpbcpu()) {
+  if(cpunum() != mpbcpu()){
     seginit();
     lapicinit(cpunum());
   }
@@ -87,9 +88,9 @@ bootothers(void)
   struct cpu *c;
   char *stack;
 
-  // Write bootstrap code to unused memory at 0x7000.  The linker has
-  // placed the start of bootother.S there.
-  code = (uchar *) 0x7000;
+  // Write bootstrap code to unused memory at 0x7000.
+  // The linker has placed the image of bootother.S in _binary_bootother_start.
+  code = (uchar*)0x7000;
   memmove(code, _binary_bootother_start, (uint)_binary_bootother_size);
 
   for(c = cpus; c < cpus+ncpu; c++){
@@ -110,4 +111,3 @@ bootothers(void)
       ;
   }
 }
-

mkfs.c

@@ -35,7 +35,7 @@ ushort
 xshort(ushort x)
 {
   ushort y;
-  uchar *a = (uchar*) &y;
+  uchar *a = (uchar*)&y;
   a[0] = x;
   a[1] = x >> 8;
   return y;
@@ -45,7 +45,7 @@ uint
 xint(uint x)
 {
   uint y;
-  uchar *a = (uchar*) &y;
+  uchar *a = (uchar*)&y;
   a[0] = x;
   a[1] = x >> 8;
   a[2] = x >> 16;
@@ -177,7 +177,7 @@ winode(uint inum, struct dinode *ip)
 
   bn = i2b(inum);
   rsect(bn, buf);
-  dip = ((struct dinode*) buf) + (inum % IPB);
+  dip = ((struct dinode*)buf) + (inum % IPB);
   *dip = *ip;
   wsect(bn, buf);
 }
@@ -191,7 +191,7 @@ rinode(uint inum, struct dinode *ip)
 
   bn = i2b(inum);
   rsect(bn, buf);
-  dip = ((struct dinode*) buf) + (inum % IPB);
+  dip = ((struct dinode*)buf) + (inum % IPB);
   *ip = *dip;
 }
 
@@ -231,7 +231,7 @@ balloc(int used)
   printf("balloc: first %d blocks have been allocated\n", used);
   assert(used < 512);
   bzero(buf, 512);
-  for(i = 0; i < used; i++) {
+  for(i = 0; i < used; i++){
     buf[i/8] = buf[i/8] | (0x1 << (i%8));
   }
   printf("balloc: write bitmap block at sector %zu\n", ninodes/IPB + 3);
@@ -243,7 +243,7 @@ balloc(int used)
 void
 iappend(uint inum, void *xp, int n)
 {
-  char *p = (char*) xp;
+  char *p = (char*)xp;
   uint fbn, off, n1;
   struct dinode din;
   char buf[512];
@@ -256,24 +256,24 @@ iappend(uint inum, void *xp, int n)
   while(n > 0){
     fbn = off / 512;
     assert(fbn < MAXFILE);
-    if(fbn < NDIRECT) {
-      if(xint(din.addrs[fbn]) == 0) {
+    if(fbn < NDIRECT){
+      if(xint(din.addrs[fbn]) == 0){
         din.addrs[fbn] = xint(freeblock++);
         usedblocks++;
       }
       x = xint(din.addrs[fbn]);
     } else {
-      if(xint(din.addrs[NDIRECT]) == 0) {
+      if(xint(din.addrs[NDIRECT]) == 0){
         // printf("allocate indirect block\n");
         din.addrs[NDIRECT] = xint(freeblock++);
         usedblocks++;
       }
       // printf("read indirect block\n");
-      rsect(xint(din.addrs[NDIRECT]), (char*) indirect);
-      if(indirect[fbn - NDIRECT] == 0) {
+      rsect(xint(din.addrs[NDIRECT]), (char*)indirect);
+      if(indirect[fbn - NDIRECT] == 0){
         indirect[fbn - NDIRECT] = xint(freeblock++);
         usedblocks++;
-        wsect(xint(din.addrs[NDIRECT]), (char*) indirect);
+        wsect(xint(din.addrs[NDIRECT]), (char*)indirect);
       }
       x = xint(indirect[fbn-NDIRECT]);
     }