[PULL 10/42] esp: introduce esp_get_stc()

[Mark Cave-Ayland]

This function simplifies reading the STC register value without having to 
manually
shift each individual 8-bit value.

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Message-Id: <20210304221103.6369-11-mark.cave-ayland@ilande.co.uk>
---
 hw/scsi/esp.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/hw/scsi/esp.c b/hw/scsi/esp.c
index dd94f7b47b..125bdea32a 100644
--- a/hw/scsi/esp.c
+++ b/hw/scsi/esp.c
@@ -116,6 +116,17 @@ static void esp_set_tc(ESPState *s, uint32_t dmalen)
     s->rregs[ESP_TCHI] = dmalen >> 16;
 }
 
+static uint32_t esp_get_stc(ESPState *s)
+{
+    uint32_t dmalen;
+
+    dmalen = s->wregs[ESP_TCLO];
+    dmalen |= s->wregs[ESP_TCMID] << 8;
+    dmalen |= s->wregs[ESP_TCHI] << 16;
+
+    return dmalen;
+}
+
 static void set_pdma(ESPState *s, enum pdma_origin_id origin,
                      uint32_t index, uint32_t len)
 {
@@ -687,9 +698,7 @@ void esp_reg_write(ESPState *s, uint32_t saddr, uint64_t 
val)
         if (val & CMD_DMA) {
             s->dma = 1;
             /* Reload DMA counter.  */
-            s->rregs[ESP_TCLO] = s->wregs[ESP_TCLO];
-            s->rregs[ESP_TCMID] = s->wregs[ESP_TCMID];
-            s->rregs[ESP_TCHI] = s->wregs[ESP_TCHI];
+            esp_set_tc(s, esp_get_stc(s));
         } else {
             s->dma = 0;
         }
-- 
2.20.1