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https://github.com/KarolS/millfork.git
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132 lines
2.2 KiB
Plaintext
132 lines
2.2 KiB
Plaintext
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#if not(ARCH_6502)
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#warn zp_reg module should be used only on 6502-compatible targets
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#endif
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noinline asm byte __mul_u8u8u8() {
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? LDA #0
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? JMP __mul_u8u8u8_start
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__mul_u8u8u8_add:
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? CLC
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? ADC __reg
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__mul_u8u8u8_loop:
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? ASL __reg
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__mul_u8u8u8_start:
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? LSR __reg+1
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? BCS __mul_u8u8u8_add
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? BNE __mul_u8u8u8_loop
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? RTS
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}
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// divide __reg[0]/__reg[1]
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noinline asm byte __mod_u8u8u8u8() {
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? LDA #0
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? LDX #7
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? CLC
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__divmod_u8u8u8u8_start:
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? ROL __reg
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? ROL
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? CMP __reg+1
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? BCC __divmod_u8u8u8u8_skip
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? SBC __reg+1
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__divmod_u8u8u8u8_skip:
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? DEX
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? BPL __divmod_u8u8u8u8_start
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? ROL __reg
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? RTS
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}
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asm byte __div_u8u8u8u8() {
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? JSR __mod_u8u8u8u8
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? LDA __reg
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? RTS
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}
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#if ZPREG_SIZE >= 3
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noinline asm word __mul_u16u8u16() {
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? LDA #0
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? TAX
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? JMP __mul_u16u8u16_start
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__mul_u16u8u16_add:
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? CLC
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? ADC __reg
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? TAY
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? TXA
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? ADC __reg+1
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? TAX
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? TYA
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__mul_u16u8u16_loop:
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? ASL __reg
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? ROL __reg+1
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__mul_u16u8u16_start:
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? LSR __reg+2
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? BCS __mul_u16u8u16_add
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? BNE __mul_u16u8u16_loop
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? RTS
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}
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// divide (__reg[1]:__reg[0])/__reg[2]
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// remainder in A, quotient in (__reg[1]:__reg[0])
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noinline asm byte __mod_u16u8u16u8() {
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? LDX #15
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? CLC
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// TODO: decide when
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#if OPTIMIZE_FOR_SPEED
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? LDA __reg+2
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? BMI __divmod_u16u8u16u8_variant2
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? LDA #0
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__divmod_u16u8u16u8_start: // for divisors <= 127
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? ROL __reg
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? ROL __reg+1
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? ROL
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? CMP __reg+2
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? BCC __divmod_u16u8u16u8_skip
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? SBC __reg+2
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__divmod_u16u8u16u8_skip:
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? DEX
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? BPL __divmod_u16u8u16u8_start
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? ROL __reg
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? ROL __reg+1
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? RTS
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#endif
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__divmod_u16u8u16u8_variant2:
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? LDA #0
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__divmod_u16u8u16u8_start2: // for divisors >= 128
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? ROL __reg
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? ROL __reg+1
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? ROL
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? BCS __divmod_u16u8u16u8_sub2
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? CMP __reg+2
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? BCC __divmod_u16u8u16u8_skip2
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__divmod_u16u8u16u8_sub2:
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? SBC __reg+2
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? SEC
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__divmod_u16u8u16u8_skip2:
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? DEX
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? BPL __divmod_u16u8u16u8_start2
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? ROL __reg
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? ROL __reg+1
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? RTS
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}
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asm word __div_u16u8u16u8() {
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? JSR __mod_u16u8u16u8
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? LDA __reg
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? LDX __reg+1
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? RTS
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}
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#endif
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#if ZPREG_SIZE >= 4
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noinline asm word call(word ax) {
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JMP ((__reg + 2))
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}
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#endif
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