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view lib/alib/mult16x8.as @ 3003:68a167bc476d
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author | Tormod Volden <debian.tormod@gmail.com> |
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date | Sun, 26 Oct 2014 13:02:12 +0100 |
parents | 03f26e88b809 |
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*********************************** * 16 x 8 Multiply (24 bit result) * OTHER MODULES NEEDED: none * ENTRY: A = multiplier * X = multiplicand * EXIT: A = product byte 1 * X = product bytes 2 & 3 nam 16x8 bit Multiply ttl Assembler Library Module section .text MULT168: PSHS A,X save numbers LEAS -3,S room for product LDB 5,S get lsb of multiplicand MUL STD 1,S save partial product LDD 3,S get mupltiplier & msb of multp. MUL ADDB 1,S add lsb to msb ADCA #0 add carry STD 0,S save sum of partial products LDX 1,S get 2 lsb's LEAS 6,S clean stack RTS endsect