nest-open-source / nest-learning-thermostat / 5.5 / x-loader / 1b7e35568a59b6561aff97c2297e4e0fd7ead16a / . / x-loader / lib / _udivsi3.S

/* # 1 "libgcc1.S" */ | |

@ libgcc1 routines for ARM cpu. | |

@ Division routines, written by Richard Earnshaw, (rearnsha@armltd.co.uk) | |

dividend .req r0 | |

divisor .req r1 | |

result .req r2 | |

curbit .req r3 | |

/* ip .req r12 */ | |

/* sp .req r13 */ | |

/* lr .req r14 */ | |

/* pc .req r15 */ | |

.text | |

.globl __udivsi3 | |

.type __udivsi3 ,function | |

.align 0 | |

__udivsi3 : | |

cmp divisor, #0 | |

beq Ldiv0 | |

mov curbit, #1 | |

mov result, #0 | |

cmp dividend, divisor | |

bcc Lgot_result | |

Loop1: | |

@ Unless the divisor is very big, shift it up in multiples of | |

@ four bits, since this is the amount of unwinding in the main | |

@ division loop. Continue shifting until the divisor is | |

@ larger than the dividend. | |

cmp divisor, #0x10000000 | |

cmpcc divisor, dividend | |

movcc divisor, divisor, lsl #4 | |

movcc curbit, curbit, lsl #4 | |

bcc Loop1 | |

Lbignum: | |

@ For very big divisors, we must shift it a bit at a time, or | |

@ we will be in danger of overflowing. | |

cmp divisor, #0x80000000 | |

cmpcc divisor, dividend | |

movcc divisor, divisor, lsl #1 | |

movcc curbit, curbit, lsl #1 | |

bcc Lbignum | |

Loop3: | |

@ Test for possible subtractions, and note which bits | |

@ are done in the result. On the final pass, this may subtract | |

@ too much from the dividend, but the result will be ok, since the | |

@ "bit" will have been shifted out at the bottom. | |

cmp dividend, divisor | |

subcs dividend, dividend, divisor | |

orrcs result, result, curbit | |

cmp dividend, divisor, lsr #1 | |

subcs dividend, dividend, divisor, lsr #1 | |

orrcs result, result, curbit, lsr #1 | |

cmp dividend, divisor, lsr #2 | |

subcs dividend, dividend, divisor, lsr #2 | |

orrcs result, result, curbit, lsr #2 | |

cmp dividend, divisor, lsr #3 | |

subcs dividend, dividend, divisor, lsr #3 | |

orrcs result, result, curbit, lsr #3 | |

cmp dividend, #0 @ Early termination? | |

movnes curbit, curbit, lsr #4 @ No, any more bits to do? | |

movne divisor, divisor, lsr #4 | |

bne Loop3 | |

Lgot_result: | |

mov r0, result | |

mov pc, lr | |

Ldiv0: | |

str lr, [sp, #-4]! | |

bl __div0 (PLT) | |

mov r0, #0 @ about as wrong as it could be | |

ldmia sp!, {pc} | |

.size __udivsi3 , . - __udivsi3 | |

/* # 235 "libgcc1.S" */ | |

/* # 320 "libgcc1.S" */ | |

/* # 421 "libgcc1.S" */ | |

/* # 433 "libgcc1.S" */ | |

/* # 456 "libgcc1.S" */ | |

/* # 500 "libgcc1.S" */ | |

/* # 580 "libgcc1.S" */ |