Difference: CallingCFunction (4 vs. 5)

Revision 52020-08-06 - PeterSchmid

Line: 1 to 1

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Calling C Functions from Forth and Vice Versa

Line: 17 to 17

r5	Variable register 2	Y	DO Limit
r6	Variable register 3	Y	Top Of Stack TOS
r7	Variable register 4	Y	Data stack pointer SPS

Changed:

<
<

r8	Variable register 5	Y	unused
r9	Platform register (usage defined by platform in use)	Y	unused

>
>

r8	Variable register 5	Y	TOS copy
r9	Platform register (usage defined by platform in use)	Y	SPS copy

r10	Variable register 7	Y	unused
r11	Variable register 8	Y	unused
r12	Intra-procedure-call scratch register	N	unused	6

Line: 57 to 57

Calling Forth Words from C Functions

Changed:

<
<

Data Stack Pointer SPS is in R7 and Top Of Stack TOS is in R6. R7 can't be a register variable, that's why R12 is used as a temporary storage.

register uint32_t TOS asm ("r6");
register uint32_t PSP asm ("r12");

TOS = TOS;
PSP = PSP;

>
> Data Stack Pointer SPS is in R7 and Top Of Stack TOS is in R6. R7 can't be a register variable, that's why R9 is used as a temporary storage.

C function FS_include() from fs.c

calls the Forth words FS_type and FS_evaluate.

Line: 83 to 75

FIL fil; /* File object */ FRESULT fr; /* FatFs return code */

Deleted:

<
<

TOS = TOS; PSP = PSP;

memcpy(path, str, count); line[count] = 0;

Line: 116 to 102

@ -----------------------------------------------------------------------------
		Wortbirne Flag_visible, "include"

Changed:

<
< @ ( "filename" -- ) Interprets the content of the file.

>
> @ ( "filename" any -- any ) Interprets the content of the file.

// void FS_include(uint8_t *str, int count) @ ----------------------------------------------------------------------------- include:

Changed:

<
< push {r0-r3, lr} bl token // ( -- c-addr len )

>
> push {lr} bl token @ ( -- c-addr len ) incl:

movs r1, tos // len -> count drop movs r0, tos // c-addr -> str drop

Changed:

<
< movs r12, psp // get psp

>
> movs r9, psp // get psp movs r8, tos // get tos

bl FS_include

Changed:

<
< movs psp, r12 // update psp pop {r0-r3, pc}

>
> movs psp, r9 // update psp movs tos, r8 // update tos pop {pc}

The C function FS_include() from fs.c calls the Forth word evaluate by the FS_evaluate() function.

Line: 137 to 126

// void FS_evaluate(uint8_t* str, int count); .global FS_evaluate FS_evaluate:

Changed:

<
< push {r4, r5, r7, lr} movs psp, r12 // get psp

>
> push {r4-r7, lr} movs psp, r9 // get psp movs tos, r8 // get tos

pushdatos movs tos, r0 // str pushdatos movs tos, r1 // count bl evaluate

Changed:

<
< movs r12, psp // update psp pop {r4, r5, r7, pc}

>
> movs r9, psp // update psp movs r8, tos // update tos pop {r4-r7, pc}

-- Peter Schmid - 2020-07-13

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