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authorYoshinori Sato <ysato@users.sourceforge.jp>2015-01-28 02:48:15 +0900
committerYoshinori Sato <ysato@users.sourceforge.jp>2015-06-23 13:35:54 +0900
commita71a29de4c2f95563220a472f265f0bd74701d52 (patch)
tree2e0b84cdc079ce9dc038d7bf3f86ebdd0315cb2e /arch/h8300/lib/mulsi3.S
parentbbeb79acb3b44f727f6267e1f6db9b3fdf791c24 (diff)
h8300: library functions
Signed-off-by: Yoshinori Sato <ysato@users.sourceforge.jp>
Diffstat (limited to 'arch/h8300/lib/mulsi3.S')
-rw-r--r--arch/h8300/lib/mulsi3.S38
1 files changed, 38 insertions, 0 deletions
diff --git a/arch/h8300/lib/mulsi3.S b/arch/h8300/lib/mulsi3.S
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+;
+; mulsi3 for H8/300H - based on Renesas SH implementation
+;
+; by Toshiyasu Morita
+;
+; Old code:
+;
+; 16b * 16b = 372 states (worst case)
+; 32b * 32b = 724 states (worst case)
+;
+; New code:
+;
+; 16b * 16b = 48 states
+; 16b * 32b = 72 states
+; 32b * 32b = 92 states
+;
+
+ .global __mulsi3
+__mulsi3:
+ mov.w r1,r2 ; ( 2 states) b * d
+ mulxu r0,er2 ; (22 states)
+
+ mov.w e0,r3 ; ( 2 states) a * d
+ beq L_skip1 ; ( 4 states)
+ mulxu r1,er3 ; (22 states)
+ add.w r3,e2 ; ( 2 states)
+
+L_skip1:
+ mov.w e1,r3 ; ( 2 states) c * b
+ beq L_skip2 ; ( 4 states)
+ mulxu r0,er3 ; (22 states)
+ add.w r3,e2 ; ( 2 states)
+
+L_skip2:
+ mov.l er2,er0 ; ( 2 states)
+ rts ; (10 states)
+
+ .end