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466
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1 <refentry id="os9">
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2 <refnamediv>
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468
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3 <refname>_os9</refname>
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4 <refpurpose>system call interface from C programs</refpurpose>
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466
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5 </refnamediv>
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6
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7 <refsynopsisdiv>
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8 <funcsynopsis>
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468
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9 <funcsynopsisinfo>
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10 #include <os9.h>
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11 </funcsynopsisinfo>
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466
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12 <funcprototype>
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468
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13 <funcdef><function>_os9</function></funcdef>
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572
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14 <paramdef>char <parameter>code</parameter></paramdef>
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15 <paramdef>struct registers *<parameter>reg</parameter></paramdef>
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466
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16 </funcprototype>
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17 </funcsynopsis>
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18
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19 </refsynopsisdiv>
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20
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21 <refsect1><title>Description</title>
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22 <para>
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602
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23 _os9 enables a programmer to access virtually any OS-9 system
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24 call directly from a C program without having to resort to
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25 assembly language routines.
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26 </para>
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27 <para>
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28 <varname>Code</varname> is one of the codes that are defines in os9.h. os9.h
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29 contains codes for the F$ and I$ function/service requests, and
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30 it also contains getstt, setstt, and error codes.
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31 </para>
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32 <para>
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33 The input registers(reg) for the system calls are accessed by
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34 the following structure that is defined in os9.h:
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35 <programlisting>
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36 struct registers {
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37 char rg_cc,rg_a,rg_b,rg_dp;
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38 unsigned rg_x,rg_y,rg_u;
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39 };
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40 </programlisting>
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41 An example program that uses _os9 is presented on the following page.
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466
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42 </para>
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43 </refsect1>
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534
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44
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45 <refsect1><title>Diagnostics</title>
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46 <para>
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47 -1 is returned is the OS-9 call failed. 0 is returned on success.
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48 </para>
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49 </refsect1>
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50
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51 <refsect1><title>Program Example</title>
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52 <programlisting>
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53 #include <os9.h>
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54 #include <modes.h>
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55
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56 /* this program does an I$GETSTT call to get file size */
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57 main(argc,argv)
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58 int argc;
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59 char **argv;
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60 {
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61 struct registers reg;
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62 int path;
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63
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64 /* tell linker we need longs */
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65 pflinit();
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66
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67 /* low level open(file name is first command line param */
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68 path=open(*++argv,S_IREAD);
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69
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70 /* set up regs for call to OS-9 */
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71 reg.rg_a=path;
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72 reg.rg_b=SS_SIZE;
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73
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74 if(_os9(I_GETSTT,&reg) == 0)
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75 printf("filesize = %lx\n", /* success */
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76 (long) (reg.rg_x << 16)+reg.rg_u);
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77 else printf("OS9 error #%d\n",reg.rg_b & 0xff); /*failed*/
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78
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79 dumpregs(&reg); /* take a look at the registers */
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80 }
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81
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82 dumpregs(r)
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83 register struct registers *r;
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84 {
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85 printf("cc=%02x\n",r->rg_cc & 0xff);
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86 printf(" a=%02x\n",r->rg_a & 0xff);
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87 printf(" b=%02x\n",r->rg_b & 0xff);
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88 printf("dp=%02x\n",r->rg_dp & 0xff);
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89 printf(" x=%02x\n",r->rg_x);
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90 printf(" y=%02x\n",r->rg_u);
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91 printf(" u=%02x\n",r->rg_y);
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92 }
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93 </programlisting>
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94 </refsect1>
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466
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95 </refentry>
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