fpudump's Introduction

fpudump

A simple, header only library to dump x87 FPU state in an OllyDbg style format. I wrote this to figure out what was going wrong with a program. Turns out there was a bug in newlib.

Example:

#include "fpu_dump.h"
...
double x = 243;
FPUDUMP;
x = x / 3.14;
FPUDUMP;

Example output:

================== MAGICAL FPU INSPECTOR ==================
From fpu_dump.c line 20:

Status: 0x0020
Invalid: 0, Denorm: 0, Zero Div: 0
Overflow: 0, Underflow: 0, Precision: 1
Stack fault: 0, Error summary: 0, TOP: 0
C3: 0, C2: 0, C1: 0, C0: 0

Control: 0x037F
Invalid Mask: 1, Denorm Mask: 1, Zero Div Mask: 1
Overflow Mask: 1, Underflow Mask: 1, Precision Mask: 1
Rounding: NEAR, Precision: 64, Infinity: 0

3 2 1 0      E S P U O Z D I
FST 0020  Cond 0 0 0 0  Err 0 0 1 0 0 0 0 0  (GT)
FCW 037F  Prec NEAR,64  Mask    1 1 1 1 1 1

ST0  EMPTY                        NAN   REG0
FFFF 00000000 00000000

ST1  EMPTY                          0   REG1
0000 00000000 00000000

ST2  EMPTY                          0   REG2
0000 00000000 00000000

ST3  EMPTY                          0   REG3
0000 00000000 00000000

ST4  EMPTY                          0   REG4
0000 00000000 00000000

ST5  EMPTY                          0   REG5
0000 00000000 00000000

ST6  EMPTY       16045690984229361664   REG6
403E DEADBEEF BAADD800

ST7  EMPTY       16045690984229355520   REG7
403E DEADBEEF BAADC0DF

========================= GOODBYE =========================

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