more

hw/8254/tpcrapi5.c

@@ -110,6 +110,69 @@ int main() {
         }
     }
 
+    printf("Again, without waiting for the first countdown.\n");
+    printf("The following test may be completely silent.\n");
+
+    for (freq=0x10000;freq >= 0x800;) {
+        t8254_pc_speaker_set_gate(PC_SPEAKER_GATE_OFF);
+        write_8254_pc_speaker((t8254_time_t)freq);
+        t8254_pc_speaker_set_gate(PC_SPEAKER_GATE_ON);
+
+        cyclesub = (0x100ul * (freq - 0x800ul)) / 0x10000ul;
+        if (cyclesub == 0) cyclesub = 1;
+
+        printf("Without waiting for first cycle, count 0x%lx sub=0x%lx... ",freq,cyclesub); fflush(stdout);
+
+        cc = read_8254(T8254_TIMER_PC_SPEAKER);
+        do {
+            pcc = cc;
+            cc = read_8254(T8254_TIMER_PC_SPEAKER);
+        } while (cc < pcc/*counts DOWN*/);
+
+        for (count=0;count < 1;count++) {
+            cc = read_8254(T8254_TIMER_PC_SPEAKER);
+            for (cycleout=0x400;cycleout < freq;cycleout += cyclesub) {
+                /* wait for countdown cycle to hit our threshhold */
+                do {
+                    pcc = cc;
+                    cc = read_8254(T8254_TIMER_PC_SPEAKER);
+                } while (cc >= cycleout);
+
+                write_8254_pc_speaker((t8254_time_t)freq);
+
+                /* wait for countdown cycle to complete */
+                do {
+                    pcc = cc;
+                    cc = read_8254(T8254_TIMER_PC_SPEAKER);
+                } while (cc < pcc/*counts DOWN*/);
+            }
+        }
+
+        printf("done\n");
+
+        if (kbhit()) {
+            c = getch();
+            if (c == 27) {
+                freq = 0;
+                break;
+            }
+            else if (c == 32) {
+                break;
+            }
+        }
+
+        if (freq > 0xFFFEu)
+            freq--;
+         else if (freq >= 0x4000u) {
+            freq -= 0x2000u;
+            freq &= ~0x1FFFu;
+        }
+        else if (freq != 0u) {
+            freq -= 0x400u;
+            freq &= ~0x3FFu;
+        }
+    }
+
     t8254_pc_speaker_set_gate(PC_SPEAKER_GATE_OFF);
     write_8254_system_timer(0); /* restore normal function to prevent BIOS from going crazy */
 	return 0;