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77 lines
1.5 KiB
ArmAsm
77 lines
1.5 KiB
ArmAsm
#include "libgcc.h"
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;; This function also computes the remainder and stores it in er3.
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.global __udivsi3
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__udivsi3:
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mov.w A1E,A1E ; denominator top word 0?
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bne DenHighNonZero
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; do it the easy way, see page 107 in manual
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mov.w A0E,A2
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extu.l A2P
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divxu.w A1,A2P
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mov.w A2E,A0E
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divxu.w A1,A0P
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mov.w A0E,A3
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mov.w A2,A0E
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extu.l A3P
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rts
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; er0 = er0 / er1
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; er3 = er0 % er1
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; trashes er1 er2
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; expects er1 >= 2^16
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DenHighNonZero:
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mov.l er0,er3
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mov.l er1,er2
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#ifdef CONFIG_CPU_H8300H
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divmod_L21:
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shlr.l er0
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shlr.l er2 ; make divisor < 2^16
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mov.w e2,e2
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bne divmod_L21
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#else
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shlr.l #2,er2 ; make divisor < 2^16
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mov.w e2,e2
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beq divmod_L22A
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divmod_L21:
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shlr.l #2,er0
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divmod_L22:
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shlr.l #2,er2 ; make divisor < 2^16
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mov.w e2,e2
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bne divmod_L21
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divmod_L22A:
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rotxl.w r2
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bcs divmod_L23
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shlr.l er0
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bra divmod_L24
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divmod_L23:
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rotxr.w r2
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shlr.l #2,er0
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divmod_L24:
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#endif
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;; At this point,
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;; er0 contains shifted dividend
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;; er1 contains divisor
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;; er2 contains shifted divisor
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;; er3 contains dividend, later remainder
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divxu.w r2,er0 ; r0 now contains the approximate quotient (AQ)
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extu.l er0
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beq divmod_L25
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subs #1,er0 ; er0 = AQ - 1
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mov.w e1,r2
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mulxu.w r0,er2 ; er2 = upper (AQ - 1) * divisor
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sub.w r2,e3 ; dividend - 65536 * er2
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mov.w r1,r2
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mulxu.w r0,er2 ; compute er3 = remainder (tentative)
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sub.l er2,er3 ; er3 = dividend - (AQ - 1) * divisor
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divmod_L25:
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cmp.l er1,er3 ; is divisor < remainder?
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blo divmod_L26
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adds #1,er0
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sub.l er1,er3 ; correct the remainder
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divmod_L26:
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rts
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.end
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