m68k/fpsp040/slog2.S

4 |       The entry point slog10 computes the base-10
8 |	sLog2 and sLog2d are the base-2 analogues.
10 |       INPUT:	Double-extended value in memory location pointed to
13 |       OUTPUT: log_10(X) or log_2(X) returned in floating-point
22 |       SPEED:	Two timings are measured, both in the copy-back mode.
34 |       Notes:    Default means round-to-nearest mode, no floating-point
40 |       Step 2.   Compute log_10(X) = log(X) * (1/log(10)).
49 |       Notes:    Default means round-to-nearest mode, no floating-point
54 |       Step 2.   Compute log_10(X) = log(X) * (1/log(10)).
63 |       Notes:    Default means round-to-nearest mode, no floating-point
69 |       Step 2.   Compute log_10(X) = log(X) * (1/log(2)).
78 |       Notes:    Default means round-to-nearest mode, no floating-point
81 |       Step 1.   If X is not an integer power of two, i.e., X != 2^k,
84 |       Step 2.   Return k.
85 |            2.1  Get integer k, X = 2^k.
87 |            2.3  Return ans := convert-to-double-extended(k).
91 |       Step 4.   Compute log_2(X) = log(X) * (1/log(2)).
102 |SLOG2    idnt    2,1 | Motorola 040 Floating Point Software Package
117 |--entry point for Log10(X), X is denormalized
120 	movel		%d1,-(%sp)
129 |--entry point for Log10(X), X is normalized
133 	movel		%d1,-(%sp)
143 |--entry point for Log2(X), X is denormalized
147 	movel		%d1,-(%sp)
156 |--entry point for Log2(X), X is normalized
161 	bnes		continue		| ...X is not 2^k
168 |--X = 2^k.
177 	movel		%d1,-(%sp)