diff options
Diffstat (limited to 'nuttx/arch/arm/src/armv7-m/up_fpu.S')
| -rw-r--r-- | nuttx/arch/arm/src/armv7-m/up_fpu.S | 29 |
1 files changed, 21 insertions, 8 deletions
diff --git a/nuttx/arch/arm/src/armv7-m/up_fpu.S b/nuttx/arch/arm/src/armv7-m/up_fpu.S index ee3644594..fd6449c2f 100644 --- a/nuttx/arch/arm/src/armv7-m/up_fpu.S +++ b/nuttx/arch/arm/src/armv7-m/up_fpu.S @@ -95,11 +95,15 @@ up_savefpu: /* Some older GNU assemblers don't support all the newer UAL mnemonics. */ #if 1 /* Use UAL mnemonics */ - /* Store all floating point registers */ + /* Store all floating point registers. Registers are stored in numeric order, + * s0, s1, ... in increasing address order. + */ vstmia r1!, {s0-s31} /* Save the full FP context */ - /* Store the floating point control and status register */ + /* Store the floating point control and status register. At the end of the + * vstmia, r1 will point to the FPCSR storage location. + */ vmrs r2, fpscr /* Fetch the FPCSR */ str r2, [r1], #4 /* Save the floating point control and status register */ @@ -180,10 +184,11 @@ up_savefpu: * * Input Parameters: * regs - A pointer to the register save area containing the floating point - * registers + * registers. * * Returned Value: - * None + * This function does not return anything explicitly. However, it is called from + * interrupt level assembly logic that assumes that r0 is preserved. * ************************************************************************************/ @@ -196,16 +201,22 @@ up_restorefpu: /* Some older GNU assemblers don't support all the newer UAL mnemonics. */ #if 1 /* Use UAL mnemonics */ - /* Load all floating point registers */ + /* Load all floating point registers. Registers are loaded in numeric order, + * s0, s1, ... in increasing address order. + */ vldmia r1!, {s0-s31} /* Restore the full FP context */ - /* Load the floating point control and status register */ + /* Load the floating point control and status register. At the end of the + * vstmia, r1 will point to the FPCSR storage location. + */ ldr r2, [r1], #4 /* Fetch the floating point control and status register */ vmsr fpscr, r2 /* Restore the FPCSR */ #else - /* Load all floating point registers */ + /* Load all floating point registers Registers are loaded in numeric order, + * s0, s1, ... in increasing address order. + */ #if 1 /* Use load multiple */ fldmias r1!, {s0-s31} /* Restore the full FP context */ @@ -260,7 +271,9 @@ up_restorefpu: vmov d15, r2, r3 /* Save as d15 */ #endif - /* Load the floating point control and status register */ + /* Load the floating point control and status register. r1 points t + * the address of the FPCSR register. + */ ldr r2, [r1], #4 /* Fetch the floating point control and status register */ fmxr fpscr, r2 /* Restore the FPCSR */ |