mirror of https://github.com/vivier/EMILE.git
57 lines
1.8 KiB
ArmAsm
57 lines
1.8 KiB
ArmAsm
/*
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*
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* (c) 2004,2005 Laurent Vivier <Laurent@Vivier.EU>
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*
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* Some parts from libgcc routines for 68000 w/o floating-point hardware.
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* Copyright (C) 1994, 1996, 1997, 1998 Free Software Foundation, Inc.
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*
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*/
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.align 2
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.globl __udivsi3
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__udivsi3:
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movel %d2, %sp@-
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movel %sp@(12), %d1 /* %d1 = divisor */
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movel %sp@(8), %d0 /* %d0 = dividend */
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cmpl #0x10000, %d1 /* divisor >= 2 ^ 16 ? */
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jcc __udivsi3L3 /* then try next algorithm */
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movel %d0, %d2
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clrw %d2
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swap %d2
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divu %d1, %d2 /* high quotient in lower word */
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movew %d2, %d0 /* save high quotient */
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swap %d0
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movew %sp@(10), %d2 /* get low dividend + high rest */
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divu %d1, %d2 /* low quotient */
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movew %d2, %d0
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jra __udivsi3L6
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__udivsi3L3: movel %d1, %d2 /* use %d2 as divisor backup */
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__udivsi3L4: lsrl #1, %d1 /* shift divisor */
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lsrl #1, %d0 /* shift dividend */
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cmpl #0x10000, %d1 /* still divisor >= 2 ^ 16 ? */
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jcc __udivsi3L4
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divu %d1, %d0 /* now we have 16-bit divisor */
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andl #0xffff, %d0 /* mask out divisor, ignore remainder */
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/* Multiply the 16-bit tentative quotient with the 32-bit divisor. Because of
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the operand ranges, this might give a 33-bit product. If this product is
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greater than the dividend, the tentative quotient was too large. */
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movel %d2, %d1
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mulu %d0, %d1 /* low part, 32 bits */
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swap %d2
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mulu %d0, %d2 /* high part, at most 17 bits */
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swap %d2 /* align high part with low part */
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tstw %d2 /* high part 17 bits? */
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jne __udivsi3L5 /* if 17 bits, quotient was too large */
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addl %d2, %d1 /* add parts */
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jcs __udivsi3L5 /* if sum is 33 bits, quotient was too large */
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cmpl %sp@(8), %d1 /* compare the sum with the dividend */
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jls __udivsi3L6 /* if sum > dividend, quotient was too large */
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__udivsi3L5: subql #1, %d0 /* adjust quotient */
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__udivsi3L6: movel %sp@+, %d2
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rts
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