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Imlac: Model MSB and LSB accumulators.

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This commit is contained in:
Lars Brinkhoff
2025-06-02 12:57:07 +02:00
committed by Paul Koning
parent 8a31996d18
commit c1904b50ce
1 changed files with 52 additions and 29 deletions
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81
imlac/imlac_dp.c
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@@ -35,7 +35,8 @@ static uint16 SP = 0;
static uint16 ON = 0;
static uint16 HALT = 0;
static uint16 MODE = 0;
static uint16 XA, YA;
static uint16 XMSB, YMSB;
static uint16 XLSB, YLSB;
static uint16 SCALE = 2;
static uint16 BLOCK = 0;
static uint16 MIT8K;
@@ -68,8 +69,10 @@ static REG dp_reg[] = {
{ ORDATAD (MODE, MODE, 1, "Display mode") },
{ BRDATAD (DT, DT, 8, 16, 8, "Return address stack") },
{ ORDATAD (SP, SP, 3, "Stack pointer") },
{ ORDATAD (XA, XA, 11, "X accumulator") },
{ ORDATAD (YA, YA, 11, "Y accumulator") },
{ ORDATAD (XMSB, XMSB, 7, "X accumulator MSB") },
{ ORDATAD (XLSB, XLSB, 5, "X accumulator LSB") },
{ ORDATAD (YMSB, YMSB, 7, "Y accumulator MSB") },
{ ORDATAD (YLSB, YLSB, 5, "Y accumulator LSB") },
{ ORDATAD (SCALE, SCALE, 3, "Scale") },
{ ORDATAD (BLOCK, BLOCK, 3, "Block") },
{ ORDATAD (MIT8K, MIT8K, 1, "MIT 8K addressing") },
@@ -167,6 +170,25 @@ dp_iot (uint16 insn, uint16 AC)
return AC;
}
static uint16 deflect (uint16 msb, uint16 lsb)
{
return (msb << 5) + lsb;
}
static void increment (uint16 *msb, uint16 *lsb, uint16 x)
{
*lsb += SCALE * x;
*msb += *lsb >> 5;
*lsb &= 037;
}
static void decrement (uint16 *msb, uint16 *lsb, uint16 x)
{
*lsb -= SCALE * x;
*msb += ((int16)*lsb) >> 5;
*lsb &= 037;
}
static t_stat
dp_opr(uint16 insn)
{
@@ -204,7 +226,7 @@ dp_opr(uint16 insn)
}
if (insn & 00020) { /* DDSP */
sim_debug (DBG, &dp_dev, "DDSP ");
crt_point (XA, YA);
crt_point (deflect (XMSB, XLSB), deflect (YMSB, YLSB));
}
if (insn & 00040) { /* DRJM */
sim_debug (DBG, &dp_dev, "DRJM ");
@@ -215,19 +237,19 @@ dp_opr(uint16 insn)
}
if (insn & 00100) { /* DDYM */
sim_debug (DBG, &dp_dev, "DDYM ");
YA -= 040;
YMSB--;
}
if (insn & 00200) { /* DDXM */
sim_debug (DBG, &dp_dev, "DDXM ");
XA -= 040;
XMSB--;
}
if (insn & 00400) { /* DIYM */
sim_debug (DBG, &dp_dev, "DIYM ");
YA += 040;
YMSB++;
}
if (insn & 01000) { /* DIXM */
sim_debug (DBG, &dp_dev, "DIXM ");
XA += 040;
XMSB++;
}
if (insn & 02000) { /* DHVC */
sim_debug (DBG, &dp_dev, "DHVC ");
@@ -296,7 +318,7 @@ dp_opt (uint16 insn)
static void
dp_inc_vector (uint16 byte)
{
uint16 x1 = XA, y1 = YA;
uint16 x1 = deflect (XMSB, XLSB), y1 = deflect (YMSB, YLSB);
uint16 dx, dy;
if (byte == 0200) {
@@ -311,19 +333,18 @@ dp_inc_vector (uint16 byte)
sim_debug (DBG, &dp_dev, "%o", byte & 3);
}
dx = SCALE * ((byte >> 3) & 3);
dy = SCALE * (byte & 3);
dx = (byte >> 3) & 3;
dy = byte & 3;
if (byte & 040)
XA -= dx;
decrement (&XMSB, &XLSB, dx);
else
XA += dx;
increment (&XMSB, &XLSB, dx);
if (byte & 4)
YA -= dy;
decrement (&YMSB, &YLSB, dy);
else
YA += dy;
increment (&YMSB, &YLSB, dy);
if (byte & 0100)
crt_line (x1, y1, XA, YA);
crt_line (x1, y1, deflect (XMSB, XLSB), deflect (YMSB, YLSB));
}
static void
@@ -347,15 +368,15 @@ dp_inc_escape (uint16 byte)
sim_debug (DBG, &dp_dev, "stack underflow");
}
if (byte & 020)
XA += 040;
XMSB++;
if (byte & 010)
XA &= 03740;
XLSB = 0;
if (byte & 4) /* Enter PPM mode. */
;
if (byte & 2)
YA += 040;
YMSB++;
if (byte & 1)
YA &= 03740;
YLSB = 0;
}
static void
@@ -382,7 +403,7 @@ dp_deim (uint16 insn)
static void
dp_dlvh (uint16 insn1, uint16 insn2, uint16 insn3)
{
uint16 x1 = XA, y1 = YA;
uint16 x1 = deflect (XMSB, XLSB), y1 = deflect (YMSB, YLSB);
uint16 m, n, dx, dy;
m = insn2 & 07777;
n = insn3 & 07777;
@@ -394,15 +415,15 @@ dp_dlvh (uint16 insn1, uint16 insn2, uint16 insn3)
dy = n;
}
if (insn3 & 040000)
XA -= SCALE * dx;
decrement (&XMSB, &XLSB, dx);
else
XA += SCALE * dx;
increment (&XMSB, &XLSB, dx);
if (insn3 & 020000)
YA -= SCALE * dy;
decrement (&YMSB, &YLSB, dy);
else
YA += SCALE * dy;
increment (&YMSB, &YLSB, dy);
if (insn2 & 020000)
crt_line (x1, y1, XA, YA);
crt_line (x1, y1, deflect (XMSB, XLSB), deflect (YMSB, YLSB));
}
static void
@@ -414,11 +435,13 @@ dp_insn (uint16 insn)
break;
case 1: /* DLXA */
sim_debug (DBG, &dp_dev, "DLXA\n");
XA = (insn & 01777) << 1;
XMSB = (insn >> 4) & 0077;
XLSB = (insn << 1) & 0036;
break;
case 2: /* DLYA */
sim_debug (DBG, &dp_dev, "DLYA\n");
YA = (insn & 01777) << 1;
YMSB = (insn >> 4) & 0077;
YLSB = (insn << 1) & 0036;
break;
case 3: /* DEIM */
sim_debug (DBG, &dp_dev, "DEIM ");