diff mbox series

[22/36] next-cube: separate rtc read and write shift logic

Message ID 20241023085852.1061031-23-mark.cave-ayland@ilande.co.uk (mailing list archive)
State New
Headers show
Series next-cube: more tidy-ups and improvements | expand

Commit Message

Mark Cave-Ayland Oct. 23, 2024, 8:58 a.m. UTC 
Introduce a new next_rtc_cmd_is_write() function to determine if an rtc command
is a read or write, and start by using it to avoid shifting the rtc input value
if a rtc read command is executed.

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
---
 hw/m68k/next-cube.c | 138 ++++++++++++++++++++++++--------------------
 1 file changed, 74 insertions(+), 64 deletions(-)
diff mbox series

Patch

diff --git a/hw/m68k/next-cube.c b/hw/m68k/next-cube.c
index bb375b63ca..4aed80c9fe 100644
--- a/hw/m68k/next-cube.c
+++ b/hw/m68k/next-cube.c
@@ -165,6 +165,12 @@  static void next_scr2_led_update(NeXTPC *s)
     }
 }
 
+static bool next_rtc_cmd_is_write(uint8_t cmd)
+{
+    return (cmd >= 0x80 && cmd <= 0x9f) ||
+           (cmd == 0xb1);
+}
+
 static void next_scr2_rtc_update(NeXTPC *s)
 {
     uint8_t old_scr2, scr2_2;
@@ -186,76 +192,80 @@  static void next_scr2_rtc_update(NeXTPC *s)
                                ((scr2_2 & SCR2_RTDATA) ? 1 : 0);
             }
             if (rtc->phase >= 8 && rtc->phase < 16) {
-                rtc->value = (rtc->value << 1) |
-                             ((scr2_2 & SCR2_RTDATA) ? 1 : 0);
-
-                /* if we read RAM register, output RT_DATA bit */
-                if (rtc->command <= 0x1F) {
-                    scr2_2 = scr2_2 & (~SCR2_RTDATA);
-                    if (rtc->ram[rtc->command] & (0x80 >> (rtc->phase - 8))) {
-                        scr2_2 |= SCR2_RTDATA;
-                    }
-
-                    rtc->retval = (rtc->retval << 1) |
-                                  ((scr2_2 & SCR2_RTDATA) ? 1 : 0);
-                }
-                /* read the status 0x30 */
-                if (rtc->command == 0x30) {
-                    scr2_2 = scr2_2 & (~SCR2_RTDATA);
-                    /* for now status = 0x98 (new rtc + FTU) */
-                    if (rtc->status & (0x80 >> (rtc->phase - 8))) {
-                        scr2_2 |= SCR2_RTDATA;
+                if (next_rtc_cmd_is_write(rtc->command)) {
+                    /* Shift in value to write */
+                    rtc->value = (rtc->value << 1) |
+                                 ((scr2_2 & SCR2_RTDATA) ? 1 : 0);
+                } else {
+                    /* Shift out value to read */
+
+                    /* if we read RAM register, output RT_DATA bit */
+                    if (rtc->command <= 0x1F) {
+                        scr2_2 = scr2_2 & (~SCR2_RTDATA);
+                        if (rtc->ram[rtc->command] &
+                            (0x80 >> (rtc->phase - 8))) {
+                                scr2_2 |= SCR2_RTDATA;
+                        }
+
+                        rtc->retval = (rtc->retval << 1) |
+                                      ((scr2_2 & SCR2_RTDATA) ? 1 : 0);
                     }
-
-                    rtc->retval = (rtc->retval << 1) |
-                                  ((scr2_2 & SCR2_RTDATA) ? 1 : 0);
-                }
-                /* read the status 0x31 */
-                if (rtc->command == 0x31) {
-                    scr2_2 = scr2_2 & (~SCR2_RTDATA);
-                    if (rtc->control & (0x80 >> (rtc->phase - 8))) {
-                        scr2_2 |= SCR2_RTDATA;
+                    /* read the status 0x30 */
+                    if (rtc->command == 0x30) {
+                        scr2_2 = scr2_2 & (~SCR2_RTDATA);
+                        /* for now status = 0x98 (new rtc + FTU) */
+                        if (rtc->status & (0x80 >> (rtc->phase - 8))) {
+                            scr2_2 |= SCR2_RTDATA;
+                        }
+
+                        rtc->retval = (rtc->retval << 1) |
+                                      ((scr2_2 & SCR2_RTDATA) ? 1 : 0);
                     }
-                    rtc->retval = (rtc->retval << 1) |
-                                  ((scr2_2 & SCR2_RTDATA) ? 1 : 0);
-                }
-
-                if ((rtc->command >= 0x20) && (rtc->command <= 0x2F)) {
-                    scr2_2 = scr2_2 & (~SCR2_RTDATA);
-                    /* for now 0x00 */
-                    time_t time_h = time(NULL);
-                    struct tm *info = localtime(&time_h);
-                    int ret = 0;
-
-                    switch (rtc->command) {
-                    case 0x20:
-                        ret = SCR2_TOBCD(info->tm_sec);
-                        break;
-                    case 0x21:
-                        ret = SCR2_TOBCD(info->tm_min);
-                        break;
-                    case 0x22:
-                        ret = SCR2_TOBCD(info->tm_hour);
-                        break;
-                    case 0x24:
-                        ret = SCR2_TOBCD(info->tm_mday);
-                        break;
-                    case 0x25:
-                        ret = SCR2_TOBCD((info->tm_mon + 1));
-                        break;
-                    case 0x26:
-                        ret = SCR2_TOBCD((info->tm_year - 100));
-                        break;
-
+                    /* read the status 0x31 */
+                    if (rtc->command == 0x31) {
+                        scr2_2 = scr2_2 & (~SCR2_RTDATA);
+                        if (rtc->control & (0x80 >> (rtc->phase - 8))) {
+                            scr2_2 |= SCR2_RTDATA;
+                        }
+                        rtc->retval = (rtc->retval << 1) |
+                                      ((scr2_2 & SCR2_RTDATA) ? 1 : 0);
                     }
 
-                    if (ret & (0x80 >> (rtc->phase - 8))) {
-                        scr2_2 |= SCR2_RTDATA;
+                    if ((rtc->command >= 0x20) && (rtc->command <= 0x2F)) {
+                        scr2_2 = scr2_2 & (~SCR2_RTDATA);
+                        /* for now 0x00 */
+                        time_t time_h = time(NULL);
+                        struct tm *info = localtime(&time_h);
+                        int ret = 0;
+
+                        switch (rtc->command) {
+                        case 0x20:
+                            ret = SCR2_TOBCD(info->tm_sec);
+                            break;
+                        case 0x21:
+                            ret = SCR2_TOBCD(info->tm_min);
+                            break;
+                        case 0x22:
+                            ret = SCR2_TOBCD(info->tm_hour);
+                            break;
+                        case 0x24:
+                            ret = SCR2_TOBCD(info->tm_mday);
+                            break;
+                        case 0x25:
+                            ret = SCR2_TOBCD((info->tm_mon + 1));
+                            break;
+                        case 0x26:
+                            ret = SCR2_TOBCD((info->tm_year - 100));
+                            break;
+                        }
+
+                        if (ret & (0x80 >> (rtc->phase - 8))) {
+                            scr2_2 |= SCR2_RTDATA;
+                        }
+                        rtc->retval = (rtc->retval << 1) |
+                                      ((scr2_2 & SCR2_RTDATA) ? 1 : 0);
                     }
-                    rtc->retval = (rtc->retval << 1) |
-                                  ((scr2_2 & SCR2_RTDATA) ? 1 : 0);
                 }
-
             }
 
             rtc->phase++;