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Annotation of researchv10no/sys/os/rdwri.c, revision 1.1.1.1

1.1       root        1: #include "sys/param.h"
                      2: #include "sys/inode.h"
                      3: #include "sys/user.h"
                      4: #include "sys/conf.h"
                      5: #include "sys/buf.h"
                      6: 
                      7: /*
                      8:  * Read the file corresponding to
                      9:  * the inode pointed at by the argument.
                     10:  * The actual read arguments are found
                     11:  * in the variables:
                     12:  *     u_base          core address for destination
                     13:  *     u_offset        byte offset in file
                     14:  *     u_count         number of bytes to read
                     15:  *     u_segflg        read to kernel/user
                     16:  */
                     17: readi(ip)
                     18: register struct inode *ip;
                     19: {
                     20: 
                     21:        if(u.u_count == 0)
                     22:                return;
                     23:        ip->i_flag |= IACC;
                     24:        if (ip->i_sptr) {
                     25:                u.u_nbadio = 0; /* approximates a bad-count per stream */
                     26:                stread(ip);
                     27:                return;
                     28:        }
                     29:        (*fstypsw[ip->i_fstyp]->t_read)(ip);
                     30: }
                     31: 
                     32: /*
                     33:  * Write the file corresponding to
                     34:  * the inode pointed at by the argument.
                     35:  * The actual write arguments are found
                     36:  * in the variables:
                     37:  *     u_base          core address for source
                     38:  *     u_offset        byte offset in file
                     39:  *     u_count         number of bytes to write
                     40:  *     u_segflg        write to kernel/user/user I
                     41:  */
                     42: 
                     43: writei(ip)
                     44: register struct inode *ip;
                     45: {
                     46: 
                     47:        if (ip->i_sptr) {
                     48:                ip->i_flag |= IUPD|ICHG;
                     49:                stwrite(ip);
                     50:                return;
                     51:        }
                     52:        (*fstypsw[ip->i_fstyp]->t_write)(ip);
                     53: }
                     54: 
                     55: /*
                     56:  * Return the logical maximum
                     57:  * of the 2 arguments.
                     58:  */
                     59: unsigned
                     60: max(a, b)
                     61: unsigned a, b;
                     62: {
                     63: 
                     64:        if(a > b)
                     65:                return(a);
                     66:        return(b);
                     67: }
                     68: 
                     69: /*
                     70:  * Return the logical minimum
                     71:  * of the 2 arguments.
                     72:  */
                     73: unsigned
                     74: min(a, b)
                     75: unsigned a, b;
                     76: {
                     77: 
                     78:        if(a < b)
                     79:                return(a);
                     80:        return(b);
                     81: }
                     82: 
                     83: /*
                     84:  * Move n bytes at byte location
                     85:  * &bp->b_un.b_addr[o] to/from (flag) the
                     86:  * user/kernel (u.segflg) area starting at u.base.
                     87:  * Update all the arguments by the number
                     88:  * of bytes moved.
                     89:  *
                     90:  * Botchy VAX-ism: believes user I and user D are the same
                     91:  */
                     92: iomove(cp, n, flag)
                     93:        register caddr_t cp;
                     94:        register unsigned n;
                     95: {
                     96:        register int t;
                     97: 
                     98:        if (n==0)
                     99:                return;
                    100:        if (u.u_segflg != SEGSYS) {
                    101:                if (flag==B_WRITE)
                    102:                        t = copyin(u.u_base, (caddr_t)cp, n);
                    103:                else
                    104:                        t = copyout((caddr_t)cp, u.u_base, n);
                    105:                if (t) {
                    106:                        u.u_error = EFAULT;
                    107:                        return;
                    108:                }
                    109:        } else
                    110:                if (flag == B_WRITE)
                    111:                        bcopy(u.u_base, (caddr_t)cp, n);
                    112:                else
                    113:                        bcopy((caddr_t)cp, u.u_base, n);
                    114:        u.u_base += n;
                    115:        u.u_offset = Lladd(u.u_offset, n);
                    116:        u.u_count -= n;
                    117: }

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