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I1401: Fixed treatment of overflow (Ken Shirriff)

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Mark Pizzolato 2015-02-09 12:30:58 -08:00
parent 960b22d930
commit 1c2aed70ba
1 changed files with 9 additions and 6 deletions
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13
I1401/i1401_cpu.c
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@ -1,6 +1,6 @@
/* i1401_cpu.c: IBM 1401 CPU simulator
Copyright (c) 1993-2012, Robert M. Supnik
Copyright (c) 1993-2015, Robert M. Supnik
Permission is hereby granted, free of charge, to any person obtaining a
copy of this software and associated documentation files (the "Software"),
@ -23,6 +23,7 @@
used in advertising or otherwise to promote the sale, use or other dealings
in this Software without prior written authorization from Robert M Supnik.
30-Jan-15 RMS Fixed treatment of overflow (Ken Shirriff)
08-Oct-12 RMS Clear storage and branch preserves B register (Van Snyder)
19-Mar-11 RMS Reverted multiple tape indicator implementation
20-Jan-11 RMS Fixed branch on EOT indicator per hardware (Van Snyder)
@ -38,8 +39,7 @@
22-Sep-05 RMS Fixed declarations (Sterling Garwood)
01-Sep-05 RMS Removed error stops in MCE
16-Aug-05 RMS Fixed C++ declaration and cast problems
02-Jun-05 RMS Fixed SSB-SSG clearing on RESET
(Ralph Reinke)
02-Jun-05 RMS Fixed SSB-SSG clearing on RESET (Ralph Reinke)
14-Nov-04 WVS Added column binary support, debug support
06-Nov-04 RMS Added instruction history
12-Jul-03 RMS Moved ASCII/BCD tables to included file
@ -963,8 +963,10 @@ CHECK_LENGTH:
M[BS] = b; /* store result */
MM (BS);
if (b & WM) { /* b wm? done */
if (qsign && (carry == 0)) /* compl, no carry? */
if ((qsign != 0) && (carry == 0)) /* eff sub and no carry? */
M[bsave] = WM + ((b & ZONE) ^ ABIT) + sum_table[10 - t];
if ((qsign == 0) && (carry != 0)) /* eff add and carry */
ind[IN_OVF] = 1; /* overflow */
break;
}
do {
@ -981,7 +983,8 @@ CHECK_LENGTH:
if ((b & WM) && (qsign == 0)) { /* last, no recomp? */
M[BS] = WM + sum_table[t] + /* zone add */
(((a & ZONE) + b + (carry? ABIT: 0)) & ZONE);
ind[IN_OVF] = carry; /* ovflo if carry */
if (carry != 0) /* carry out? */
ind[IN_OVF] = 1; /* ovflo if carry */
}
else M[BS] = (b & WM) + sum_table[t]; /* normal add */
MM (BS);