Call to floating point routine problem

I have a single precision floating point routine in my ASM file, which I am trying to call from my C code. I've never had a problem doing this before, but it doesn't seem to be working with a floating argument. If I define the variables angle and n as floats as shown below, the disassembler shows that the assignment of 2.5 to angle properly stores it as a single word. When I call the sinsp function, the disassembly shows conversion of the variable to a double at 304b88 before it calls the routine. Is this a compiler bug or have I missed something? I seems that the compiler should know that the variable is single precision as it was defined, and pass it that way in A4.

Thanks for your help,

Ron

// from the C file

 float   angle,n;

 angle = 2.5;

 n = sinsp(angle);

// disassembly

2531

       angle = 2.5;

          C$RL393:

00804b78:   0180A358            MVK.L1        0,A3

00804b7c:   E1200082            .fphead       n, l, W, BU, nobr, nosat, 0001001

00804b80:   01A01068            MVKH.S1       0x40200000,A3

00804b84:   ECB5                   STW.D2T1      A3,*B15[7]

2532

       n = sinsp(angle);

00804b86:   91C7                    MV.L2X        A3,B4

00804b88:   021000A2            SPDP.S2       B4,B5:B4

00804b8c:   2C6E                   NOP           2

00804b8e:   9246                    MV.L1X        B4,A4

00804b90:   10021F13           CALLP.S2      sinsp (PC+4344 = 0x00805c78),B3

00804b94:   02941FD8 ||        OR.L1X        0,B5,A5           C$RL394:

00804b98:   01900958            INTSP.L1      A4,A3

00804b9c:   E1400000            .fphead       n, l, W, BU, nobr, nosat, 0001010

00804ba0:   4C6E                   NOP           3

00804ba2:   8D35                   STW.D2T1      A3,*B15[8] 2533       for(angle = 2.75;angle < 5.5;angle += .01){

; from ASM file - cossp/sinsp copied from mathlib

         .global _cossp

         .global _sinsp

;---------------------------------------------------------------------------------------------

; cossp.asm - single precision floating point cosine

;              optimized hand ASM single sample

   .newblock

PIo2ssp  .set    0x3fc90fdb      ; PI/2 = 1.5707964 (in SP FP)

InvPissp .set    0x3ea2f983      ; 1/PI = 0.31830987

C1ssp    .set    0x40490000      ; C1   = 3.1406250

C2ssp    .set    0x3a7daa22      ; C2   = 9.6765358e-4

s4ssp    .set    0x362e9c5b      ; s4   = 2.6019031e-6

s3ssp    .set    0xb94fb222      ; s3   =-1.9807418e-4

s2ssp    .set    0x3c08873e      ; s2   = 8.3330255e-3

s1ssp    .set    0xbe2aaaa4      ; s1   =-1.6666657e-1

PIssp    .set    0x40490fdb      ; PI   = 3.1415927

; SP FP Cosine _cossp:                       ; entry for SP FP Cosine function (radians)

            mvkl    .S2     PIo2ssp,B6           ; SP FP PI/2 = 1.5707964

 ||         clr     .S1     A4,31,31,A4          ; arg1 = |arg1|

            mvkh    .S2     PIo2ssp,B6

            addsp   .L1x    B6,A4,A4             ; new arg1 = |arg1| + PI/2

            nop             1                    ; wait for cosine new arg1

                                                 ; continues into SP FP Sine

 _sinsp:                       ; entry for SP FP Sine function (radians)

            mvkl    .S1     InvPissp,A5          ; T = 1/Pi

            mvkh    .S1     InvPissp,A5

            mv      .L2X    A4,B4

            extu    .S2     B4,1,1,B4            ; Y = absolute arg1

            mpysp   .M2X    B4,A5,B5             ; X = Y*(1/Pi)

            nop             3                    ; wait for mpysp X

            spint   .L2     B5,B5                ; X = int(X)

            mvkl    .S1     C1ssp,A5             ; T = C1 coef.

            mvkh    .S1     C1ssp,A5

            nop             1                    ; wait for spint X

            intsp   .L2     B5,B1                ; Z = float (X)

            nop             3                    ; wait for intsp Z

            mpysp   .M1X    B1,A5,A3             ; F = X * C1