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synced 2025-04-08 09:28:19 +02:00
- Split division routines out into an include file.
- Reuse division routines for calculating both division and modulus. - Add implementations of BsfByte and BsrByte that don't use a lookup table. git-svn-id: trunk@42494 -
This commit is contained in:
Jeppe Johansen
parent
ff3372567f
commit
4b93eb64b3
1
.gitattributes
vendored
1
.gitattributes
vendored
@ -8975,6 +8975,7 @@ rtl/atari/xbios.inc svneol=native#text/plain
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rtl/avr/avr.inc svneol=native#text/plain
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rtl/avr/cpuh.inc svneol=native#text/plain
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rtl/avr/cpuinnr.inc svneol=native#text/plain
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rtl/avr/divide.inc svneol=native#text/plain
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rtl/avr/int64p.inc svneol=native#text/plain
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rtl/avr/intrinsics.pp svneol=native#text/pascal
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rtl/avr/makefile.cpu svneol=native#text/plain
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137
rtl/avr/divide.inc
Normal file
137
rtl/avr/divide.inc
Normal file
@ -0,0 +1,137 @@
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// Based on restoring division algorithm
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// Algorithm source document: Lecture notes by S. Galal and D. Pham, Division algorithms and hardware implementations.
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// Link to documentation http://www.seas.ucla.edu/~ingrid/ee213a/lectures/division_presentV2.pdf
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// Also refer to description on Wikipedia: https://en.wikipedia.org/wiki/Division_algorithm#Restoring_division
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// Note that the algorithm automatically yields the following results for special cases:
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// z div 0 = MAX(type)
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// 0 div 0 = MAX(type)
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// 0 div n = 0
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// Checks for z = 0; n = [0,1]; n = z and n > z could shortcut the algorithm for speed-ups
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// but would add extra code
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// Perhaps add the checks depending on optimization settings?
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// z in Ra, n in Rb, 0 in Rp
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function fpc_divmod_byte(n, z: byte): byte; assembler; nostackframe;
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label
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div1, div2, div3, finish;
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asm
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// Symbol Name Register(s)
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// z (A) dividend R22
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// n (B) divisor R24
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// p (P) remainder R20
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// i counter R18
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clr R20 // clear remainder
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ldi R18, 8 // iterate over 8 bits
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div1:
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lsl R22 // shift left A
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rol R20 // shift left P with carry from A shift
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sub R20, R24 // Subtract B from P, P <= P - B
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brlo div2
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ori R22, 1 // Set A[0] = 1
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rjmp div3
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div2: // negative branch, A[0] = 0 (default after shift), restore P
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add R20, R24 // restore old value of P
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div3:
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dec R18
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brne div1
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finish:
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mov R24, R22 // Move result from R22 to R24
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end;
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// z in Ra, n in Rb, 0 in Rp
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function fpc_divmod_word(n, z: word): word; assembler; nostackframe;
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label
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div1, div2, div3, finish;
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asm
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// Symbol Name Register(s)
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// z (A) dividend R23, R22
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// n (B) divisor R25, R24
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// p (P) remainder R21, R20
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// i counter R18
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clr R20 // clear remainder low
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clr R21 // clear remainder hi
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ldi R18, 16 // iterate over 16 bits
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div1:
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lsl R22 // shift left A_L
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rol R23
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rol R20 // shift left P with carry from A shift
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rol R21
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sub R20, R24 // Subtract B from P, P <= P - B
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sbc R21, R25
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brlo div2
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ori R22, 1 // Set A[0] = 1
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rjmp div3
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div2: // negative branch, A[0] = 0 (default after shift), restore P
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add R20, R24 // restore old value of P
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adc R21, R25
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div3:
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dec R18
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brne div1
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finish:
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movw R24, R22 // Move result from R22:R23 to R24:R25
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end;
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// z in Ra, n in Rb, 0 in Rp
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function fpc_divmod_dword(n, z: dword): dword; assembler; nostackframe;
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label
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div1, div2, div3, finish;
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asm
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// Symbol Name Register(s)
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// z (A) dividend R21, R20, R19, R18
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// n (B) divisor R25, R24, R23, R22
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// p (P) remainder R17, R16, R15, R14 -> Returned in R25, R24, R23, R22
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// i counter R26
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push R17
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push R16
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push R15
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push R14
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clr R14 // clear remainder
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clr R15 // clear remainder
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clr R16
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clr R17
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ldi R26, 32 // iterate over 32 bits
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div1:
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lsl R18 // shift left A_L
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rol R19
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rol R20
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rol R21
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rol R14 // shift left P with carry from A shift
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rol R15
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rol R16
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rol R17
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sub R14, R22 // Subtract B from P, P <= P - B
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sbc R15, R23
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sbc R16, R24
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sbc R17, R25
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brlo div2
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ori R18, 1 // Set A[0] = 1
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rjmp div3
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div2: // negative branch, A[0] = 0 (default after shift), restore P
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add R14, R22 // restore old value of P
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adc R15, R23
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adc R16, R24
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adc R17, R25
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div3:
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dec R26
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brne div1
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finish:
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movw R22, R14 // Move remainder into reg that is not volatile
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movw R24, R16
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pop R14
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pop R15
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pop R16
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pop R17
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end;
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341
rtl/avr/math.inc
341
rtl/avr/math.inc
@ -14,81 +14,31 @@
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**********************************************************************}
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// Based on restoring division algorithm
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// Algorithm source document: Lecture notes by S. Galal and D. Pham, Division algorithms and hardware implementations.
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// Link to documentation http://www.seas.ucla.edu/~ingrid/ee213a/lectures/division_presentV2.pdf
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// Also refer to description on Wikipedia: https://en.wikipedia.org/wiki/Division_algorithm#Restoring_division
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{$i divide.inc}
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// Note that the algorithm automatically yields the following results for special cases:
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// z div 0 = MAX(type)
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// 0 div 0 = MAX(type)
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// 0 div n = 0
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// Checks for z = 0; n = [0,1]; n = z and n > z could shortcut the algorithm for speed-ups
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// but would add extra code
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// Perhaps add the checks depending on optimization settings?
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// z (dividend) = q(quotient) x n(divisor) + p(remainder)
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{$ifndef FPC_SYSTEM_HAS_DIV_BYTE}
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{$define FPC_SYSTEM_HAS_DIV_BYTE}
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// z (dividend) = q(quotient) x n(divisor) + p(remainder)
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// z in Ra, n in Rb, 0 in Rp
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function fpc_div_byte(n, z: byte): byte; assembler; nostackframe;
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{$ifdef FPC_IS_SYSTEM}[public,alias: 'FPC_DIV_BYTE'];{$endif}
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label
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start, div1, div2, div3, finish;
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asm
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// Symbol Name Register(s)
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// z (A) dividend R22
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// n (B) divisor R24
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// p (P) remainder R20
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// i counter R18
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cp R24, R1
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brne start
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brne .LNonZero
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{$ifdef CPUAVR_HAS_JMP_CALL}
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call get_pc_addr
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call fpc_divbyzero
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.LNonZero:
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call fpc_divmod_byte
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{$else CPUAVR_HAS_JMP_CALL}
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rcall get_pc_addr
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{$endif CPUAVR_HAS_JMP_CALL}
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movw R20, R24
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{$ifdef CPUAVR_HAS_JMP_CALL}
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call get_frame
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{$else CPUAVR_HAS_JMP_CALL}
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rcall get_frame
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{$endif CPUAVR_HAS_JMP_CALL}
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movw R18, R24
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ldi R22, 200
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clr R23
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clr R24
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clr R25
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{$ifdef CPUAVR_HAS_JMP_CALL}
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call HandleErrorAddrFrameInd
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{$else CPUAVR_HAS_JMP_CALL}
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rcall HandleErrorAddrFrameInd
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rcall fpc_divbyzero
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.LNonZero:
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rcall fpc_divmod_byte
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{$endif CPUAVR_HAS_JMP_CALL}
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start:
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clr R20 // clear remainder
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ldi R18, 8 // iterate over 8 bits
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div1:
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lsl R22 // shift left A
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rol R20 // shift left P with carry from A shift
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sub R20, R24 // Subtract B from P, P <= P - B
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brlo div2
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ori R22, 1 // Set A[0] = 1
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rjmp div3
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div2: // negative branch, A[0] = 0 (default after shift), restore P
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add R20, R24 // restore old value of P
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div3:
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dec R18
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brne div1
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finish:
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mov R24, R22 // Move result from R22 to R24
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mov R24, R22
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end;
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{It is a compilerproc (systemh.inc), make an alias for internal use.}
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@ -97,70 +47,57 @@ function fpc_div_byte(n, z: byte): byte; external name 'FPC_DIV_BYTE';
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{$endif FPC_IS_SYSTEM}
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{$endif FPC_SYSTEM_HAS_DIV_BYTE}
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{$ifndef FPC_SYSTEM_HAS_MOD_BYTE}
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{$define FPC_SYSTEM_HAS_MOD_BYTE}
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// z in Ra, n in Rb, 0 in Rp
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function fpc_mod_byte(n, z: byte): byte; assembler; nostackframe;
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{$ifdef FPC_IS_SYSTEM}[public,alias: 'FPC_MOD_BYTE'];{$endif}
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asm
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cp R24, R1
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brne .LNonZero
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{$ifdef CPUAVR_HAS_JMP_CALL}
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call fpc_divbyzero
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.LNonZero:
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call fpc_divmod_byte
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{$else CPUAVR_HAS_JMP_CALL}
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rcall fpc_divbyzero
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.LNonZero:
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rcall fpc_divmod_byte
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{$endif CPUAVR_HAS_JMP_CALL}
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mov R24, R20
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end;
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{It is a compilerproc (systemh.inc), make an alias for internal use.}
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{$ifdef FPC_IS_SYSTEM}
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function fpc_mod_byte(n, z: byte): byte; external name 'FPC_MOD_BYTE';
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{$endif FPC_IS_SYSTEM}
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{$endif FPC_SYSTEM_HAS_MOD_BYTE}
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{$ifndef FPC_SYSTEM_HAS_DIV_WORD}
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{$define FPC_SYSTEM_HAS_DIV_WORD}
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// z in Ra, n in Rb, 0 in Rp
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function fpc_div_word(n, z: word): word; assembler; nostackframe;
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{$ifdef FPC_IS_SYSTEM}[public,alias: 'FPC_DIV_WORD'];{$endif}
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label
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start, div1, div2, div3, finish;
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asm
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// Symbol Name Register(s)
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// z (A) dividend R23, R22
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// n (B) divisor R25, R24
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// p (P) remainder R21, R20
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// i counter R18
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cp R24, R1
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brne start
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cpc R25, R1
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brne .LNonZero
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{$ifdef CPUAVR_HAS_JMP_CALL}
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call get_pc_addr
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call fpc_divbyzero
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.LNonZero:
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call fpc_divmod_word
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{$else CPUAVR_HAS_JMP_CALL}
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rcall get_pc_addr
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{$endif CPUAVR_HAS_JMP_CALL}
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movw R20, R24
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{$ifdef CPUAVR_HAS_JMP_CALL}
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call get_frame
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{$else CPUAVR_HAS_JMP_CALL}
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rcall get_frame
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{$endif CPUAVR_HAS_JMP_CALL}
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movw R18, R24
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ldi R22, 200
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clr R23
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clr R24
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clr R25
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{$ifdef CPUAVR_HAS_JMP_CALL}
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call HandleErrorAddrFrameInd
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{$else CPUAVR_HAS_JMP_CALL}
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rcall HandleErrorAddrFrameInd
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rcall fpc_divbyzero
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.LNonZero:
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rcall fpc_divmod_word
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{$endif CPUAVR_HAS_JMP_CALL}
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start: // Start of division...
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clr R20 // clear remainder low
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clr R21 // clear remainder hi
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ldi R18, 16 // iterate over 16 bits
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div1:
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lsl R22 // shift left A_L
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rol R23
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rol R20 // shift left P with carry from A shift
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rol R21
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sub R20, R24 // Subtract B from P, P <= P - B
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sbc R21, R25
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brlo div2
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ori R22, 1 // Set A[0] = 1
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rjmp div3
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div2: // negative branch, A[0] = 0 (default after shift), restore P
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add R20, R24 // restore old value of P
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adc R21, R25
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div3:
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dec R18
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brne div1
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finish:
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movw R24, R22 // Move result from R22:R23 to R24:R25
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movw R24, R22
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end;
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{It is a compilerproc (systemh.inc), make an alias for internal use.}
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@ -170,95 +107,60 @@ function fpc_div_word(n, z: word): word; external name 'FPC_DIV_WORD';
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{$endif FPC_SYSTEM_HAS_DIV_WORD}
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{$ifndef FPC_SYSTEM_HAS_MOD_WORD}
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{$define FPC_SYSTEM_HAS_MOD_WORD}
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// z in Ra, n in Rb, 0 in Rp
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function fpc_mod_word(n, z: word): word; assembler; nostackframe;
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{$ifdef FPC_IS_SYSTEM}[public,alias: 'FPC_MOD_WORD'];{$endif}
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asm
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cp R24, R1
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cpc R25, R1
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brne .LNonZero
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{$ifdef CPUAVR_HAS_JMP_CALL}
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call fpc_divbyzero
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.LNonZero:
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call fpc_divmod_word
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{$else CPUAVR_HAS_JMP_CALL}
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rcall fpc_divbyzero
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.LNonZero:
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rcall fpc_divmod_word
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{$endif CPUAVR_HAS_JMP_CALL}
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movw R24, R20
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end;
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{It is a compilerproc (systemh.inc), make an alias for internal use.}
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{$ifdef FPC_IS_SYSTEM}
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function fpc_mod_word(n, z: word): word; external name 'FPC_MOD_WORD';
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{$endif FPC_IS_SYSTEM}
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{$endif FPC_SYSTEM_HAS_MOD_WORD}
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{$ifndef FPC_SYSTEM_HAS_DIV_DWORD}
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{$define FPC_SYSTEM_HAS_DIV_DWORD}
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// z in Ra, n in Rb, 0 in Rp
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function fpc_div_dword(n, z: dword): dword; assembler; nostackframe;
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{$ifdef FPC_IS_SYSTEM}[public,alias: 'FPC_DIV_DWORD'];{$endif}
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label
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start, div1, div2, div3, finish;
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asm
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// Symbol Name Register(s)
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// z (A) dividend R21, R20, R19, R18
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// n (B) divisor R25, R24, R23, R22
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// p (P) remainder R17, R16, R15, R14
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// i counter R26
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cp R24, R1
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cpc R25, R1
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cpc R22, R1
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cpc R23, R1
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brne .LNonZero
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{$ifdef CPUAVR_HAS_JMP_CALL}
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call get_pc_addr
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{$else CPUAVR_HAS_JMP_CALL}
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rcall get_pc_addr
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{$endif CPUAVR_HAS_JMP_CALL}
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movw R20, R24
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{$ifdef CPUAVR_HAS_JMP_CALL}
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call get_frame
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{$else CPUAVR_HAS_JMP_CALL}
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rcall get_frame
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{$endif CPUAVR_HAS_JMP_CALL}
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movw R18, R24
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ldi R22, 200
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clr R23
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clr R24
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clr R25
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{$ifdef CPUAVR_HAS_JMP_CALL}
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call HandleErrorAddrFrameInd
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{$else CPUAVR_HAS_JMP_CALL}
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rcall HandleErrorAddrFrameInd
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{$endif CPUAVR_HAS_JMP_CALL}
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call fpc_divbyzero
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.LNonZero:
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push R17
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push R16
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push R15
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push R14
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call fpc_divmod_dword
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{$else CPUAVR_HAS_JMP_CALL}
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rcall fpc_divbyzero
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.LNonZero:
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rcall fpc_divmod_dword
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{$endif CPUAVR_HAS_JMP_CALL}
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start: // Start of division...
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clr R14 // clear remainder
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clr R15 // clear remainder
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clr R16
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clr R17
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ldi R26, 32 // iterate over 32 bits
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div1:
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lsl R18 // shift left A_L
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rol R19
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rol R20
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rol R21
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rol R14 // shift left P with carry from A shift
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rol R15
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rol R16
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rol R17
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sub R14, R22 // Subtract B from P, P <= P - B
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sbc R15, R23
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sbc R16, R24
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sbc R17, R25
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brlo div2
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ori R18, 1 // Set A[0] = 1
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rjmp div3
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div2: // negative branch, A[0] = 0 (default after shift), restore P
|
||||
add R14, R22 // restore old value of P
|
||||
adc R15, R23
|
||||
adc R16, R24
|
||||
adc R17, R25
|
||||
|
||||
div3:
|
||||
dec R26
|
||||
brne div1
|
||||
|
||||
finish:
|
||||
movw R22, R18 // Move result from R18:R21 to R22:R25
|
||||
movw R24, R20
|
||||
|
||||
pop R14
|
||||
pop R15
|
||||
pop R16
|
||||
pop R17
|
||||
end;
|
||||
|
||||
{It is a compilerproc (systemh.inc), make an alias for internal use.}
|
||||
@ -267,3 +169,72 @@ function fpc_div_dword(n, z: dword): dword; external name 'FPC_DIV_DWORD';
|
||||
{$endif FPC_IS_SYSTEM}
|
||||
{$endif FPC_SYSTEM_HAS_DIV_DWORD}
|
||||
|
||||
|
||||
{$ifndef FPC_SYSTEM_HAS_MOD_DWORD}
|
||||
{$define FPC_SYSTEM_HAS_MOD_DWORD}
|
||||
|
||||
// z in Ra, n in Rb, 0 in Rp
|
||||
function fpc_mod_dword(n, z: dword): dword; assembler; nostackframe;
|
||||
{$ifdef FPC_IS_SYSTEM}[public,alias: 'FPC_MOD_DWORD'];{$endif}
|
||||
asm
|
||||
cp R24, R1
|
||||
cpc R25, R1
|
||||
cpc R22, R1
|
||||
cpc R23, R1
|
||||
brne .LNonZero
|
||||
{$ifdef CPUAVR_HAS_JMP_CALL}
|
||||
call fpc_divbyzero
|
||||
.LNonZero:
|
||||
call fpc_divmod_dword
|
||||
{$else CPUAVR_HAS_JMP_CALL}
|
||||
rcall fpc_divbyzero
|
||||
.LNonZero:
|
||||
rcall fpc_divmod_dword
|
||||
{$endif CPUAVR_HAS_JMP_CALL}
|
||||
end;
|
||||
|
||||
{It is a compilerproc (systemh.inc), make an alias for internal use.}
|
||||
{$ifdef FPC_IS_SYSTEM}
|
||||
function fpc_mod_dword(n, z: dword): dword; external name 'FPC_MOD_DWORD';
|
||||
{$endif FPC_IS_SYSTEM}
|
||||
{$endif FPC_SYSTEM_HAS_MOD_DWORD}
|
||||
|
||||
|
||||
{$ifndef FPC_SYSTEM_HAS_BSF_BYTE}
|
||||
{$define FPC_SYSTEM_HAS_BSF_BYTE}
|
||||
|
||||
function BsfByte(Const AValue: Byte): Byte;
|
||||
var
|
||||
i, value: byte;
|
||||
begin
|
||||
Value:=AValue;
|
||||
for i:=0 to 7 do
|
||||
begin
|
||||
if odd(Value) then
|
||||
exit(i);
|
||||
Value:=Value shr 1;
|
||||
end;
|
||||
result:=$FF;
|
||||
end;
|
||||
|
||||
{$endif}
|
||||
|
||||
|
||||
{$ifndef FPC_SYSTEM_HAS_BSR_BYTE}
|
||||
{$define FPC_SYSTEM_HAS_BSR_BYTE}
|
||||
|
||||
function BsrByte(Const AValue: Byte): Byte;
|
||||
var
|
||||
i, value: byte;
|
||||
begin
|
||||
Value:=AValue;
|
||||
for i:=0 to 7 do
|
||||
begin
|
||||
if (Value and $80)<>0 then
|
||||
exit(i);
|
||||
Value:=Value shl 1;
|
||||
end;
|
||||
result:=$FF;
|
||||
end;
|
||||
|
||||
{$endif}
|
||||
|
||||
Loading…
Reference in New Issue
Block a user