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--- en:multiasm:papc:chapter_6_10 [2025/10/31 14:05] – [FPU] ktokarz
+++ en:multiasm:papc:chapter_6_10 [2025/10/31 16:28] (current) – [Table] ktokarz
@@ Line 164: / Line 164: @@
 ===== Transcendental instructions =====
 The transcendental instructions perform calculations of advanced mathematical functions.
-FSIN Sine.
+The **fsin** instruction calculates the sine, while the **fcos** calculates the cosine of the argument stored in ST(0). The **fsincos** calculates both sine and cosine with the same instruction. The sine is returned in ST(1), the cosine in ST(0). The **fptan** instruction calculates the partial tangent and **fpatan** the partial arctangent. After calculating the tangent, the value of 1.0 is pushed onto the stack to make it easier to calculate cotangent afterwards by execution **fdivr** instruction. The partial means that this instruction handles only a limited range of input arguments.
-FCOS Cosine.
+The instructions for exponential and logarithmic functions are summarised in table {{ref>ftrans}}.
-FSINCOS Sine and cosine.
+<table ftrans>
-FPTAN Partial tangent.
+<caption>Transcendental arithmetic instructions</caption>
-FPATAN Partial arctangent.
+^ Mnemonic     ^ operation                              ^ note on operands        ^
-F2XM1 2x − 1.
+| **f2xm1**    | {{ :en:multiasm:cs:f2xm1.png?105 }}    |                         |
-FYL2X y∗log2x.
+| **fyl2x**    | {{ :en:multiasm:cs:fyl2x.png?105 }}    | y is ST(1); x is ST(0)  |
-FYL2XP1 y∗log2(x+1).
+| **fyl2xp1**  | {{ :en:multiasm:cs:fyl2xp1.png?105 }}  | y is ST(1); x is ST(0)  |
+</table>
+===== FPU control instructions =====
+The FPU control instructions help the programmer to save and restore the contents of chosen registers if there is a need to use them in an interrupt handler or inside a function. It is also possible to initialise the state of the FPU unit or clear errors.
+The **fincstp** increments and **fdecstp** decrements the FPU register stack pointer.
+The following set of instructions can perform error checking while execution (instructions without "N") or perform the operation without checking for error conditions (instructions without "N").
+The **finit** and **fninit** initialise the FPU (after checking error conditions or without checking error conditions).
+The **fclex** and **fnclex** clear floating-point exception flags.
+The **fstcw** and **fnstcw** store the FPU control word.
+The **fldcw** loads the FPU control word.
+The **fstenv** and **fnstenr** store the FPU environment. The environment consists of the FPU control word, status
+word, tag word, instruction pointer, data pointer, and last opcode register.
+The **fldenv** loads the FPU environment.
+The **fsave** and **fnsave** save the FPU state. The state is the operating environment and full register stack.
+The **frstor** restores the FPU state.
+The **fstsw** and **fnstsw** store the FPU status word. There is no instruction for restoring the status word.
+The **wait** or **fwait** waits for the FPU to finish the operation.
+The **fnop** instruction is the no operation instruction for the FPU.

en/multiasm/papc/chapter_6_10.1761919510.txt.gz · Last modified: 2025/10/31 14:05 by ktokarz