src/dps8/dps8_append.h

/* */
This source file includes following definitions.
set_apu_status
fauxDoAppendCycle
   1 /*
   2  * vim: filetype=c:tabstop=4:ai:expandtab
   3  * SPDX-License-Identifier: ICU
   4  * scspell-id: 506d89bb-f62d-11ec-b87a-80ee73e9b8e7
   5  *
   6  * ---------------------------------------------------------------------------
   7  *
   8  * Copyright (c) 2013-2017 Charles Anthony
   9  * Copyright (c) 2021-2022 The DPS8M Development Team
  10  *
  11  * All rights reserved.
  12  *
  13  * This software is made available under the terms of the ICU
  14  * License, version 1.8.1 or later.  For more details, see the
  15  * LICENSE.md file at the top-level directory of this distribution.
  16  *
  17  * ---------------------------------------------------------------------------
  18  */
  19 
  20 // Appending unit stuff .......
  21 
  22 // Once segno and offset are formed in TPR.SNR and TPR.CA, respectively, the
  23 // process of generating the 24-bit absolute main memory address can involve a
  24 // number of different and distinct appending unit cycles.
  25 //
  26 // The operation of the appending unit is shown in the flowchart in Figure 5-4.
  27 // This flowchart assumes that directed faults, store faults, and parity faults
  28 // do not occur.
  29 //
  30 // A segment boundary check is made in every cycle except PSDW. If a boundary
  31 // violation is detected, an access violation, out of segment bounds, fault is
  32 // generated and the execution of the instruction interrupted. The occurrence
  33 // of any fault interrupts the sequence at the point of occurrence. The
  34 // operating system software should store the control unit data for possible
  35 // later continuation and attempt to resolve the fault condition.
  36 //
  37 // The value of the associative memories may be seen in the flowchart by
  38 // observing the number of appending unit cycles bypassed if an SDW or PTW is
  39 // found in the associative memories.
  40 //
  41 // There are nine different appending unit cycles that involve accesses to main
  42 // memory. Two of these (FANP, FAP) generate the 24-bit absolute main memory
  43 // address and initiate a main memory access for the operand, indirect word, or
  44 // instruction pair; five (NSDW, PSDW, PTW, PTW2, and DSPTW) generate a main
  45 // memory access to fetch an SDW or PTW; and two (MDSPTW and MPTW) generate a
  46 // main memory access to update page status bits (PTW.U and PTW.M) in a PTW.
  47 // The cycles are defined in Table 5-1.
  48 
  49 // enum _appendingUnit_cycle_type {
  50 //     apuCycle_APPUNKNOWN = 0,    // unknown
  51 //
  52 //     apuCycle_FIAP,       // Fetch instruction
  53 //
  54 //     apuCycle_FANP,       // Final address nonpaged.
  55 //               // Generates the 24-bit absolute main memory address and
  56 //               // initiates a main memory access to an unpaged segment for
  57 //               // operands, indirect words, or instructions.
  58 //
  59 //     apuCycle_FAP,        // Final address paged
  60 //               // Generates the 24-bit absolute main memory address and
  61 //               // initiates a main memory access to a paged segment for
  62 //               // operands, indirect words, or instructions.
  63 //
  64 //     apuCycle_NSDW,       // Nonpaged SDW Fetch
  65 //               // Fetches an SDW from an unpaged descriptor segment.
  66 //
  67 //     apuCycle_PSDW,       // Paged SDW Fetch
  68 //               // Fetches an SDW from a paged descriptor segment.
  69 //
  70 //     apuCycle_PTWfetch,   // PTW fetch
  71 //               // Fetches a PTW from a page table other than a descriptor
  72 //               // segment page table and sets the page accessed bit (PTW.U).
  73 //
  74 //     apuCycle_PTW2,       // Prepage PTW fetch
  75 //               // Fetches the next PTW from a page table other than a
  76 //               // descriptor segment page table during hardware prepaging for
  77 //               // certain uninterruptible EIS instructions. This cycle does
  78 //               // not load the next PTW into the appending unit. It merely
  79 //               // assures that the PTW is not faulted (PTW.F = 1) and that
  80 //               // the target page will be in main memory when and if needed
  81 //               // by the instruction.
  82 //
  83 //     apuCycle_DSPTW,      // Descriptor segment PTW fetch
  84 //              // Fetches a PTW from a descriptor segment page table.
  85 //
  86 //     apuCycle_MDSPTW,     // Modify DSPTW
  87 //              // Sets the page accessed bit (PTW.U) in the PTW for a page
  88 //              // in a descriptor segment page table. This cycle always
  89 //              // immediately follows a DSPTW cycle.
  90 //
  91 //     apuCycle_MPTW        // Modify PTW
  92 //              // Sets the page modified bit (PTW.M) in the PTW for a page
  93 //              // in other than a descriptor segment page table.
  94 // };
  95 
  96 // These bits are aligned to match the CU word 0 APU status bit positions.
  97 // This produces some oddness in the scu save/restore code.
  98 
  99 typedef enum apuStatusBits
 100   {
 101     apuStatus_PI_AP  = 1u << (35 - 24), //  -AP Instruction fetch append cycle
 102     apuStatus_DSPTW  = 1u << (35 - 25), //  Fetch descriptor segment PTW
 103     apuStatus_SDWNP  = 1u << (35 - 26), //  Fetch SDW non paged
 104     apuStatus_SDWP   = 1u << (35 - 27), //  Fetch SDW paged
 105     apuStatus_PTW    = 1u << (35 - 28), //  Fetch PTW
 106     apuStatus_PTW2   = 1u << (35 - 29), //  Fetch prepage PTW
 107     apuStatus_FAP    = 1u << (35 - 30), //  Fetch final address - paged
 108     apuStatus_FANP   = 1u << (35 - 31), //  Fetch final address - nonpaged
 109     apuStatus_FABS   = 1u << (35 - 32), //  Fetch final address - absolute
 110 
 111     // XXX these don't seem like the right solution.
 112     // XXX there are MDSPTW and MPTW bits in the APU history
 113     // register, but not in the CU.
 114 
 115     apuStatus_MDSPTW = 1u << (35 - 25), //  Fetch descriptor segment PTW
 116     apuStatus_MPTW   = 1u << (35 - 28)  //  Fetch PTW
 117   } apuStatusBits;
 118 
 119 static inline void set_apu_status (apuStatusBits status)
     /*  */
 120   {
 121     word12 FCT = cpu.cu.APUCycleBits & MASK3;
 122     cpu.cu.APUCycleBits = (status & 07770) | FCT;
 123   }
 124 
 125 #ifdef TESTING
 126 t_stat dump_sdwam (void);
 127 #endif
 128 word24 do_append_cycle (processor_cycle_type thisCycle,
 129                       word36 * data, uint nWords);
 130 void do_ldbr (word36 * Ypair);
 131 void do_sdbr (word36 * Ypair);
 132 void do_camp (word36 Y);
 133 void do_cams (word36 Y);
 134 #ifdef TESTING
 135 int dbgLookupAddress (word18 segno, word18 offset, word24 * finalAddress,
 136                       char * * msg);
 137 #endif
 138 sdw0_s * getSDW (word15 segno);
 139 
 140 static inline void fauxDoAppendCycle (processor_cycle_type thisCycle)
     /*  */
 141   {
 142     cpu.apu.lastCycle = thisCycle;
 143   }
/* */
root/src/dps8/dps8_append.h

INCLUDED FROM

DEFINITIONS
