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--- en:multiasm:papc:chapter_6_10 [2025/10/31 15:08] – [Transcendental instructions] ktokarz
+++ en:multiasm:papc:chapter_6_10 [2025/10/31 16:28] (current) – [Table] ktokarz
@@ Line 168: / Line 168: @@
 <table ftrans>
 <caption>Transcendental arithmetic instructions</caption>
-^ Mnemonic     ^ operation                              ^ note                    ^
+^ Mnemonic     ^ operation                              ^ note on operands        ^
 | **f2xm1**    | {{ :en:multiasm:cs:f2xm1.png?105 }}    |                         |
 | **fyl2x**    | {{ :en:multiasm:cs:fyl2x.png?105 }}    | y is ST(1); x is ST(0)  |
@@ Line 175: / Line 175: @@
 ===== 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_10.1761923307.txt.gz · Last modified: 2025/10/31 15:08 by ktokarz