' ========================================================================= ' ' File...... wordcomparing.SXB ' Purpose... Demonstrates comparing words (16bit register values) ' ' ========================================================================= ' ------------------------------------------------------------------------- ' Device Settings ' ------------------------------------------------------------------------- DEVICE SX28, OSC4MHZ, TURBO, STACKX, OPTIONX FREQ 4_000_000 ID "CMP16" ' ------------------------------------------------------------------------- ' IO Pins ' ------------------------------------------------------------------------- ' ------------------------------------------------------------------------- ' Constants ' ------------------------------------------------------------------------- ' unsigned test actual unsigned results ' X = Y X < Y X > Y ' X = Y b0 True False False ' X < Y b1 False True False ' X <= Y b2 True True False ' X > Y b3 False False True ' X >= Y b4 True False True ' X <> Y b5 False True True ' ' signed test if unsigned X < Y ' if X>=0 AND Y<0 then use column for X > Y ' signed test if unsigned X > Y ' if X<0 AND Y>=0 then use column for X < Y ' the above results in: ' signed test if unsigned X <> Y ' if sign(X) <> sign(Y) then swap column 'unsigned test attributes uEQ con 1 uLT con 2 uLE con 4 uGT con 8 uGE con 16 uNE con 32 'signed test attributes EQ con 128+1 LT con 128+2 LE con 128+4 GT con 128+8 GE con 128+16 NE con 128+32 'unsigned compare flags EQflags con %00010101 LTflags con %00100110 GTflags con %00111000 XORvalue con %00011110 'to swap LTflags and GTflags for some signed tests true con 1 false con 0 ' ------------------------------------------------------------------------- ' Variables ' ------------------------------------------------------------------------- ramX VAR Word ' 16-bit value ramY VAR Word ' 16-bit value attrib VAR Byte ' compare attribute result VAR Word flags VAR Byte ' ========================================================================= PROGRAM Start ' ========================================================================= ' ------------------------------------------------------------------------- ' Subroutine Declarations ' ------------------------------------------------------------------------- ' ------------------------------------------------------------------------- ' Program Code ' ------------------------------------------------------------------------- Start: 'assume ramX, ramY and attrib are set 'at the end result holds true or false based on X and Y values and the test to perform 'get unsigned compare flags if ramX = ramY then flags = EQflags else if ramX < ramY then flags = LTflags else flags = GTflags endif endif 'if signed compare then adjust compare flags if attrib.7 = 1 then 'if ramX <> ramY if flags.0 = 0 then result_MSB = ramX_MSB xor ramY_MSB 'if ramX and ramY have different signs if result.15 = 1 then flags = flags xor XORvalue 'swap LTflags and GTflags endif endif endif result = 0 'extract flag for test flags = flags and attrib 'set result based on flag result.0 = ~Z 'if flags=0 (Z set) then result=false ramX=$FF01 ramY=$FF00 attrib = LT gosub doTest END asm getUnsignedCompareFlags: mov w,ramX_LSB mov w,ramY_LSB-w mov result_LSB,w mov w,ramX_MSB sb C ;skip if no borrow movsz w,++ramX_MSB mov w,ramY_MSB-w or w,result_LSB snz retw EQflags ;ramX = ramY snb C retw LTflags ;ramX < ramY retw GTflags ;ramX > ramY ;assume ramX, ramY and attrib set doTest: call getUnsignedCompareFlags mov flags,w jnb attrib.7,test2 jb flags.0,test2 mov w,ramX_MSB xor w,ramY_MSB and w,#$80 mov w,#XORvalue sz xor flags,w test2: clr result_LSB mov w,attrib and flags,w sz inc result_LSB clr result_MSB ret endasm ' ------------------------------------------------------------------------- ' Subroutine Code ' -------------------------------------------------------------------------
file: /Techref/scenix/lib/flow/compcon16signed.htm, 4KB, , updated: 2006/8/18 13:51, local time: 2024/10/9 17:39,
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