ASL: Difference between revisions

Latest revision as of 10:42, 19 December 2023


Basic Info
Addressing Mode	Opcode	Length	Speed
Accumulator	0A	1 byte	2 cycles
Absolute	0E	3 bytes	6 cycles*
Direct Page	06	2 bytes	5 cycles*
absolute indexed X	1E	3 bytes	7 cycles*
direct page indexed X	16	2 bytes	6 cycles*


Flags Affected
N	V	M	X	D	I	Z	C
	.	.	.	.	.

ASL (Arithmetic Shift Left) is a 65x instruction that shifts a value by left one bit (multiplication by two). The most significant bit is shifted into the carry flag. The least significant bit becomes a zero.

Cycle Penalties

Except in accumulator addressing, ASL takes two extra cycles when the accumulator is 16 bits wide
In direct page addressing modes, ASL takes another extra cycle if the low byte of the direct page register is nonzero.

External Links

Eyes & Lichty page 427, on ASL: https://archive.org/details/0893037893ProgrammingThe65816/page/n453
lbid page 190, before & after diagram of ASL: https://archive.org/details/0893037893ProgrammingThe65816/page/n216
Labiak page 117 on ASL: https://archive.org/details/Programming_the_65816/page/n127
MCS6500 Manual page 149 on ASL: https://archive.org/details/mos_microcomputers_programming_manual/page/n170
https://archive.org/details/mos_microcomputers_programming_manual/page/n205
Carr page 247 on ASL: https://archive.org/details/6502UsersManual/page/n260
Leventhal page 3-41 on ASL: https://archive.org/details/6502-assembly-language-programming/page/n90
undisbeliever on ASL: https://undisbeliever.net/snesdev/65816-opcodes.html#asl-arithmetic-shift-left

@@ Line 1: / Line 1: @@
-'''ASL''' (Arithmetic Shift Left) is a 65x instruction that shifts a value by left one bit (multiplication by two).  The most significant bit is shifted into the [[carry flag]].  The least significant bit becomes a zero.
+{| class="wikitable" style="float:right;clear:right;width:40%"
-{| class="wikitable" style="float:right;clear:right;width:30%"
 !colspan="8"|Basic Info
 |+
@@ Line 9: / Line 7: @@
 |'''Speed'''
 |+
-|accumulator
+|[[Accumulator Addressing|Accumulator]]
 |0A
 |1 byte
 |2 cycles
 |+
-|absolute
+|[[Absolute]]
 |0E
 |3 bytes
-|6 cycles
+|6 cycles*
 |+
-|direct page
+|[[Direct Page Addressing|Direct Page]]
 |06
 |2 bytes
-|5 cycles
+|5 cycles*
 |+
 |absolute indexed X
 |1E
 |3 bytes
-|7 cycles
+|7 cycles*
 |+
 |direct page indexed X
 |16
 |2 bytes
-|6 cycles
+|6 cycles*
 |}
-{| class="wikitable" style="width:30%"
+{| class="wikitable" style="float:right;clear:right;width:30%"
-!colspan="9"|Flags Clobbered
+!colspan="9"|Flags Affected
 |+
-|N
+|[[N Flag|N]]
-|V
+|[[V Flag|V]]
-|M
+|[[M Flag|M]]
-|X
+|[[X Flag|X]]
-|D
+|[[D Flag|D]]
-|I
+|[[I Flag|I]]
-|Z
+|[[Z Flag|Z]]
-|C
+|[[C Flag|C]]
 |+
 |
@@ Line 56: / Line 54: @@
 |
 |}
+'''ASL''' (Arithmetic Shift Left) is a 65x instruction that shifts a value by left one bit (multiplication by two).  The most significant bit is shifted into the [[carry flag]].  The least significant bit becomes a zero.
+===== Cycle Penalties =====
+* Except in [[accumulator addressing]], ASL takes two extra cycles when the accumulator is 16 bits wide
+* In [[direct page addressing]] modes, ASL takes another extra cycle if the low byte of the [[direct page register]] is nonzero.
 === See Also ===
 * [[LSR]]
+* [[ASL (SPC700)]]
 === External Links ===
-* [[Eyes & Lichty]] page on ASL: https://archive.org/details/0893037893ProgrammingThe65816/page/n453
+* [[Eyes & Lichty]] page 427, on ASL: https://archive.org/details/0893037893ProgrammingThe65816/page/n453
-* [[Labiak]] page on ASL: https://archive.org/details/Programming_the_65816/page/n127
+* lbid page 190, before & after diagram of ASL: https://archive.org/details/0893037893ProgrammingThe65816/page/n216
-* [[MCS6500 Manual]] page on ASL: https://archive.org/details/mos_microcomputers_programming_manual/page/n170
+* [[Labiak]] page 117 on ASL: https://archive.org/details/Programming_the_65816/page/n127
-* [[Carr]] page on ASL: https://archive.org/details/6502UsersManual/page/n260
+* [[MCS6500 Manual]] page 149 on ASL: https://archive.org/details/mos_microcomputers_programming_manual/page/n170
-* [[Leventhal]] page on ASL: https://archive.org/details/6502-assembly-language-programming/page/n90
+* https://archive.org/details/mos_microcomputers_programming_manual/page/n205
+* [[Carr]] page 247 on ASL: https://archive.org/details/6502UsersManual/page/n260
+* [[Leventhal]] page 3-41 on ASL: https://archive.org/details/6502-assembly-language-programming/page/n90
+* undisbeliever on ASL: https://undisbeliever.net/snesdev/65816-opcodes.html#asl-arithmetic-shift-left
 [[Category:ASM]]